The forums are retiring and are now closed for new topics and comments. The existing content will remain online and accessible through 2020 to provide everyone the opportunity to save any relevant information. In the spring of 2021, these Community forums will be taken offline.

Search for surface hardness in Topics


Distinguish glass hard disk platters from aluminum without marring the reflective surface? Answered

I have hundreds of hard disk platters from disassembled hard drives.  Some are made of glass, some are made of aluminum.  The glass ones, when flexed, shatter into thousands of razor shards which screech across the room. I would like to avoid that in the future.  I only want to use the aluminum ones, but I don't want to mar the reflective surface. I've thought of weighing them, but the platters some from many manufacturers and eras and so the weights won't be consistent.  Magnets don't attract glass or aluminum. Does glass float? (I'm guessing no.)  Is the reflective surface transparent? (I'm guessing no again, but maybe a strong light would work?) There has to be a way....

Question by Odonata    |  last reply


How to cut aluminum hard drive platters?

After determining that a hard drive platter is aluminum (I don't want to try to cut the glass ones), how could I cut it neatly?  I'd like to cut out neat rectangles for a small kaleidoscope.  I tried a hacksaw, but it was a messy cut, and I expect it bent the optical surface a bit.  I tried a rotary tool with cut-off discs, but the aluminum chewed up the discs really fast--I could see the discs shrinking before my eyes into tiny circles.  

Question by arpruss    |  last reply


Labrador has strange phobia of unusual floor surfaces? Answered

Does anyone has an explanation? My labrador is in perfect health; no balance problems; he leaps fences and is not timid in any way. A few years ago when we laid down slate floor tiles on the entire diner and kitchen area he seems  worried about walking on the kitchen area and avoids it or approaches it very gingerly, bowing low as he does so; it's as if he perceives it as a deep hole . He will, however, totally forget about this fear if he can get to the cat's food but otherwise it is very hard coaxing him onto the tiles in the kitchen only. My friend's  exterior  landing and staircase has a mottled pattern; he just couldn't walk on it and refused to come down it; he had to be carried. So, none of this is a problem at all, but I'm just curious to see if anyone has encountered anything similar? Thanks.

Question by FriendOfHumanity    |  last reply


need a jig for cuttin styrofoam straight/smooth surfaces?

I'm trying to get into lost foam (aluminum) casting, so I just build a styrofoam cutter ("frame" with a hot-wire). It's pretty difficult to handle because it melts trough the styrofoam so quickly and it's hard to hold perfectly straight and every movement makes an impression in the styrofoam part. I need some ideas on how to make a jig that makes it easy(er) to make smooth surfaces in the styrofoam part, I was thinking something that adjusts the distance between the hot wire and the table/surface and then just slide the styrofoam across the table/surface through the hotwire for making plates (easy), but I need to be able to change the distancee between the surface and the hotwire for different thinknesses but also somehow be able to make angles and hopefully also somehow ROUND PIECES AND CYLINDERS :o hope you can give me some inputs :D and even better some pictures, drawings and links thianks!

Question by lordl9999    |  last reply


How to make a 3D printed Montana face mask

The internet is now literally flooded with these great face masks.People are even selling them for profit in blatnt violation of the creators intentions.A lot of people like me, with a 3D printer have abandoned their projects and ressources for the greater good.If is now us "geeks" making a huge difference in our local communities.I have accumulated few tricks when it comes to these masks over the last few weeks and kg of filament.The number one complaint if you dare to call a nice request a complaint is that the printed surface is often too hard to clean.The Montana mask needs to be printed in either PLA or PETG as other plastic can't tolerate the harsh sanitizer requirements over a long time.Nylon would work fine as well but is too difficult to deal with in the machine and severly limits the options to glue or stick anything onto the material.Be aware that PETG is a true pain here as well!Ok, PLA it is but how can we all speed the printing up and produce an even better surface finnish?The key like with ABS to use a solvent to either perform a vapour cloud smoothing or to brush or even spray the solvent onto the surface.Added beneift is that you can repair minor damages or imperfections quite easy instead of wasting the mask.PLA is "organic" to go with the food hype here.That means common solvents used in biolabs will work just fine.Hey! You forgot to tell us what solvent to use!!Sorry, my bad :(Use Ethylacetate the same way you would use Acetone on ABS.Dissolve some PLA in it to make a thin slurry or as said just brush it on with a suitable brush a few times until you get the desired surface quality.No Ethylacetate at hand? No problem ;)One word though: Please use level 3 PPE when dealing with the ingredients or concentrated solvent!That means chemical and acid proof gloves, apron and face shield.For making it you should also use a fume hood or at least a breathing apparatus/filter maks with acivated carbon layers.You need concentrated Acetic Acid, also called Glacial Acid is it will freeze at about 17°C.You also need ethanol of at least 98% - no methylated spirit, denatured alcohol or such things if you can as the end product will contain the contaminants.Slowly add the acid to a small amount of the alcohol.Use a glas stirrer or similar to mix it a little bit.Use indicator paper to check for the acidity.Once it gets acidic add a small amount of alcohol to get into the neutral zone again.You can dry the product using the common drying agents for solvents that contain water as by your chemical book or preference.Again: Please be advised that Glacial acetic acid is not only extremely harmful but also highly flammable and that it can explode under the wrong handling conditions.Whenever possible you should obtain Ethylacetate solution from a proper chemical supplier to avoid the hazard of making your own.Do not attempt if you are not used to and trained to handle dangerous chemicals!Once the mask has the required finnish let the solvent evaporate off over nigh in a well ventialted area.After that a simple wash with soapy water followed by a sanitation with bleech solution makes the mask reay to pack and seal.

Topic by Downunder35m  


what smd components can I use to make a voltage regulator? Answered

I have components from a laptop hard drive and would like to know which components on the controller board can be used to make a voltage regulator that regulates voltages at 3,6,9 and 12 volts.

Question by techfix1    |  last reply


can you put bondo on plaster of paris? Answered

Can you put bondo on plaster of paris? i want to put some kind of filler on a rounded styrofoam shape, and then use bondo to make it look like a hard plastic or metal surface

Question by William930    |  last reply


Can I mix cement, aggregate, and water in place?

I have a 250 sq. ft. area that has 2" of pea gravel on top of clay.  Can I mix cement into the gravel then water from the top to get a surface hard enough to put pavers or stones on?

Question by Silvermist73    |  last reply


Recycling stuff for cool fridge magnets!

Recyle your old broken hard drives. Take them apart and scrounge the powerful magnets out. They make great ways to attach anything to your fridge or metal surface. See my 64 Corvette Stingray Fridge Magnet Instructable. It has flashing tailights! As ever -TRIUMPHMAN.

Topic by triumphman  


Green sand options? Answered

I finally finnished my testing prototype of my metal melting furnace. Did a few casts to get short rods for the lathe work and noticed a big problem. I used washed play sand as itwas the finest sand I could find locally. The result was good in shape but very bad in terms of surface quality. For another test I used the leftovers of my crushed perlite and mixed it bentonite and the surface was really smooth - but using perlite is not really an option. Real green sand is hard to get in my area and the postage costs for a 20kg bag are just too high on top of it. So, before I start hunting down all sand and soils shops nearby: Is there a proper name for extreme fine sand or a good alternative for a reusable casting media?

Question by Downunder35m    |  last reply


Mirror acrylic Glue

Hey,I have been researching the best way to glue acrylic mirror together into a cube the same as the picture attached. So far I have been told it is quiet hard but Dichloro is what my supplier was able to find out. I have read a lot of health hazards and difficulty getting hold of it. Is there any that would be able to point me in the right direction.With my normal acrylic i just use a weldbond etc but the mirrored surface would not be suited.Thanks in advance everyone.

Question by PeteH66    |  last reply


New Idea but I don't know how to make it

Hey all, I was just looking at some photos on some photographers website in a series called Beautiful Decay. I had looked at maybe two or three when I suddenly had an idea. I know some various ways of aging things, primarily metal, but there is one style of aging which must technically be possible but I am coming up with only a few possibilities as to how to do it on my own: flaking paint. So far I have thought of dabbing on paint thinner before spraying to make it have a weak bond to the surface or adding powder (probably whatever the surface is, just ground up) for the same effect and then with the weak bond simply sweeping over the area with a broom several times to flake the paint. These seem like they would be hard to make seem natural. a second idea that kind of fits in is fake rust. By that I mean that the surface looks old and rusty (get your tetanus booster kind of thing) but is actually fully protected from the elements. Any ideas you have are welcome and I thank you for them in advance.

Topic by finfan7    |  last reply


Can anyone tell me for sure what material the Western Digital HD are made? They shine like mirrors and seems steel. Answered

I dismantled an old WD HD 2.5 Gb to use the neodymium magnet, and to my surprise I found that instead of a disc, it had three, stacked. I was also surprised for its mirror finish, I expected a dark brown surface, like floppies. Can anyone tell me for sure what material they are made the discs? Aluminum is not, must be steel, but it must be stainless steel or be well covered, because they shine like mirrors.  

Question by rimar2000    |  last reply


antique school bell

OK, i got this antique school bell, i think the date reads 1898 idk its got a little surface rust, i saw this thing sitting on a shelf, and i thought to my self  "how awesome would that be to be hooked up to a door bell" but no matter how hard i look i cant find clear instructions on how to, and what i need to make it work. Ive put some power on it and the hammer just stuck to the coil instead of bouncing back forth. are there any antique gurus who can help me with this issue?   thanks :P

Topic by golddigger1559    |  last reply


Built from scratch computer desk help (woodworking)

Hey world, i was wondering if any carpentry buffs out there could give me a hand, i have a very simple project: a desk using only 4 pieces of straight board, one for the top surface, 2 for the sides/legs, and one for support. (if you're having trouble visualizing it, look at the pic below). what i need help with is what kind of wood to use, i was thinking some hard wood, but i dont know what would be most cost effective (not goin for beauty here, it'll all be painted in the end) I plan to make a bunch of cut outs in the surface so i can incorperate things like an ipod dock, slots for papers and holes for wires to be hidden. I dont know if that would help determine what kind of wood to use, but i assume every bit of info i can provide would help :) thanks in advance! ADRENIHOLIC

Topic by Adrenaholic    |  last reply


Solar Filter for Telescopes

Having seen some predictions of increased solar activity over the next two years, I decided to make a filter so I can check it out with my trusty telescope. To start out, I constructed the rig shown in photo A, and practiced with it by cutting disks of plain glass. Make a table like that in photo C so you can make a continuous score on the glass, without stopping. Put oil on the wheel of the grass cutter. Be sure that the surface you work on is flat. You can skip this if you want a square filter. After scoring, your glass should look like that in photo B, with a uniform and even cut. Next, put the scored glass on a soft surface like a mouse pad, with the scored surface wetted with water and face down. Press on the back of the score with a dull nail to start a crack. By continual pressing you can watch the crack propagate all the way around. Then, make 8 radial scores from the circle to the edge of the glass and propagate those cracks in the same manner as the disk. When you do it right, you get a result like photo D, where the pieces were separated for illustration. When you get good at this with regular glass, you can cut the mirror into a disk. With the mirror, you score the glass on the side that has the metal coating. Or, you can just cut the mirror in a square instead of a circle. Photo E shows an uncut and a finished cut mirror. The mirror came out of the back of a discarded projection TV. Some of the mirrors are plastic films, some are second surface, some are first surface glass but the metal coating is too thin. There are many variations, but you need to find a first surface glass mirror that reduces the light level by 12 stops (as measured by a LunaPro SBC light meter). Photographically, this is like reducing the light level from F1.4 to F64. This level of light reduction will be hard to find. WARNING: Use of a mirror with a thin reflective coating can result in eye damage if used to view the sun through a telescope. I have access to a smaller commercial filter to use as a guide. This filter produced a bright blue image of the sun, so I added a red filter at the eyepiece. This combination produced a normal yellow image of the sun. There were no significant sunspots visible, so I didn’t bother taking any pictures. The Filter is mounted to a screw-in lens cap.

Topic by ShutterBugger    |  last reply


Ancient technologies revisited - drilling and machining

In the ruins of our ancient world we often see exceptional accuracy for surfaces but also clear indications of machining work that should have been impossible back then,For quite a few of these impossibilities modern scientists, inventors and people that just like to experiment came up with plausible conclusions.So let's start with a few of them...Core drilling...It is a process were a rather large hole is not actually drilled but cut out.Imagine a piece of pipe you press into some clay - that's what you end up with.A circular, deep hole with a standing core inside, break the core off and you are good to go.Doing this with copper or brass tools as the only available metal tools seems feasable.If it is something soft like sand stone but for things like granite???Ancient texts provided some clues, like that slow spinning tubes were used or that drilling a 2m deep hole did only take a few hours.Appearently it was done in less than half a day - a day being daylight.Modern diamond drilling tools would still struggle to create such a deep hole in that time unless you pay a fortune for a custom made drill bit.One clue that was nagging these people for a long times was how it was possible to reach these high penetration speeds.The marks on core samplesand holes clearly show and almost spiral pattern, indicating the "drill" went deeper by a few mm with just a few rotations of the drill.The calculated pressure required to do this is about equal to having a tank parked on top of your drill....Impossible I know...Hammer drill differences give us another clue here.Take you homedepot drill that can drill in metal and stone - it runs fast and although it does the job the tradesmen tool does it better.Not because it is way more expensive but because it is purpose made by running slower but with a much more powerfull impact for the drill bit.How do you create a massive impact with copper or brass?Those who tried a copper drill will tell you they are no good for anything.Those who tried a copper core drill will tell you the same.Too soft, deforms too quickly, no "teeth" that last for more than a few seconds.But is that really true???These soft metals seem to have a feature that makes them special: They can be "work hardened".Like the top end of your cold chisel "peeling"...Of course the harness levels you can achieve are still very short of being even like soft steel.Every material has a resonant frequency, even hard rock like granite.A technique called sonic drilling utilises this as an advantage.The drill is subjected to an audio signal that is very close or matching a harmonic frequency of the rock in question.There is even nice Youtube videos showing how two stones are flattened against each other just with loudspeakers and some wire to hold them together.The same guy posted videos showing that core drilling is possible this way too.The science behind it is still not a 100% understood though.Several universities did their own experiments here and here are some of the more modern explanations why it works despite being impossible:The vibrations cause surface fractures on contact, a bit like when your dentist cleans your teeth with this screaming thing...The contact surface of the drill actually does not do any impact damage, it simply acts as a transducer horn for the vibrations.In their tests it was even confirmed that steel tools are no good here as the material would mean you need very long tools due to the resonant nodes forming differently in denser material.Most interesting was that these aido drills can be literally of any shape you like.Not hard to create a fancy symbol shape from copper pipe - and then to vibrate it into the surface to create writing....Several ancient cultures show clear tooling marks in their carved symbol creations while others seemed to have "melted" the symbol into the rock - audio only ;)Extreme accuracy for planar faces....Be it the walls of an ancient "coffin", box or chamber, we can find a lot of them with an accuracy that even today we would fail to achieve.A solid granit like block with a perfectly square box cut out of it.Several examples exist where the accuracy couldn't be done with modern tools at all.Less than 0.5% divergence from true parallel walls and corners with a rounded inner edge with a radius of less than 2mm....Audio machining is not feasable for this one.And with literally no surface marks scientists were baffled for decades.Due to the size it would mean that for a tiny error you would have to re-do the entire surface of the affected wall.And with a surface so highly polished that even after a few tausand years it still reflects light....Samples taken showed another conundrum - glacing...Almost as if the stone was melted, pressed flat and then repeated until the entire surface was done.The temperautres required for this however are said to be impossible in ancient times, same for any tools capable of tolerating such heat without melting.So this theory was discarded for a very long time and deemed to be interpretation error - after all they had no chance to do this thausands of years ago.Later it was discovered that you actually can use two identically hard stone surfaces to grind them perfectly flat against each other.And well, using the right, mild abbresives it is even possible to give the surface a nice shine.Yes, the theory is sound but can't explain how one would machine the corners like this....The inside of a square or rectangular box can't be produced like this.Plus the problem of actually removing all the unwanted material first.In recent years the old samples taken were subject to new studies, this time in regards to the possibility that the surface was polished using heat.Surprisingly a mix of high temps and cold water allows for quite accurated destruction of the surface.Relatively easy to remove some bumps by just heating the bump and spraying a mist of cold water over it.Still not possible to create perfect corners but a start.It failed to reproduce the shine and polished surface too.Then, as a last resort you might say, lasers were used on rocks of similar or identical composition.The classic CO2 laser is a brute force tool and although accuracy would be possible you wouldn't get a good surface as it does not melt, it just cracks like glass.Femto second lasers were great here but could not provide any glacing effect either.Problem was always that the stone could not soak up any of the laser energy.It would not heat up evenly, only very locally where the laser was hitting the surface and no depth either.Then they finally got the idea to use tiny samples in a wide laser beam.A wavelength more suited to heat rather than vaporise and energy levels per mm² much, much lower than in a focussed beam.No problem to actually fully melt the sample without create any cracks or to adjust the parameters so the core still remains solid for a true glazing effect.Funny side effect of fully molten samples were their extreme surface hardness - very similar to what we find in ancient leftovers we can't explain.On bigger samples two effects were observed.Firstly that of a flat surface with the sample being rather thick, a too fast cooling down would result in the entire surface that was heated to split off.Secondly that the resulting surface was still extremely flat and even.Sadly we can not find any real evidence that ancient cultures knew about how to use high energy lasers with adjustable focus....And so far no one was able to come up with any theory that explains ALL the features of a perfect stone box with polished surfaced, especially if the surfaced is glaced.The ancient lathe....We can see the evidence of large boulders machined on some gigantic lathe through the ancient world, especially in greece and the middle east.And so far the best archeologists could come up with was that some guy sat there for days hammering the surface until a template provided a perfect fit.What they failed to explain was how this guy did this in a true rotary fashion.But the beauty of archeology is that these guys can claim what they like without being required to provide backing of their claims - not their territory OLIn several places we found leftovers of contraptions deemed to be the remains of some grinding mechanism to make flour or maby fine powder from rocks for mortar.But every mill needs a mlling stone - they were never found anywhere.And if the "mount" that remains clearly indicates it was able to be moved in the X and Y direction it would have been a very strange flour mill indeed.In the real world you would only have to move the grinding stone up and even that is mostly optional.The real clue however is how complicated it would have been to collect the flour.No one wants to use a broom to get it off the floor in a desert environment....With the wearmarks on the bottom stone it would have been impossible to produce flour, so why would it have been used for decades more if the flour was no good anyway?Again, outsiders provided vital clues by creating small models of these ancient "flour mills".The ground around them shows wear marks identical to someone running in a circle since the dawn of time.At quite a distance to the center I might add.If horses or cows were used to go in said circle with a harness you could spin quite some weight - like a round piller stone.And the bottom "pan" could be filled with fine sand or similar to act as a rudimentary bearing.The rounded bottom and indentation on the top of ancient piller stones seems suddenly more plausible to be the result of these "flour mills" - they self centered the block for machining.Push your tool(s) against the surface and make sure they keep the tension, then sit back and watch the animals do the hard work for you.Nothing fancy about it, just a vertical lathe driven by animals instead of a big motor and gear box...Won't explain though how some cultures were able to create perfectly round pillars of 20 or more meters in length in one piece....In many places we can observe impossible fitments, like a lid on a stone box that won't even require a sealant to be perfectly air tight.Or in India and other parts of the east intricate stone figurines that are hollowed out - with carved details on the inside.So not just some holes and simple cavities, more like 3D printed.Several experts of their fields, from artists over stone masons to jewlery makers tried to re-create some of these features using modern tools - they all failed badly.You simply can't use a rotating tool if you need to get around several corners to reach the surface to be machined.So how were the ancient builders and artists able to do the impossible?Some say that ancient texts and images tell us that the stone was melted away, like bee's wax.The glacing effect on these surfaces seems to confirm this but we all know you can't melt rock, especially not in a controlled way to create artwork.Rock is not ice - or is it?High frequency ultrasonic machining allows us to work with very hard rock, like cutting through butter with a hot knife.No sharp tools required either.The only problem is that you need very hard tools with a high tensile strenght and "good acoustics" - like titanium as the prefered option in the industry for ultrasonic horns and amplifiers.They did not have titanium in the ancient world and they certainly did not have power outlet to drive some ultrasonic tools.But they did know their acoustics as the "musical temple" in India shows.Hit a pillar, some plate or even statue and they all produce a very accurate frequency, despite the entire temple being carved out of one solid mountain piece...You can not create this today even if you had a clue how to carve it out of the mountain!!No way to create delicated designs that all have individual but extreme accurate musical notes when hit...Means the ancient builder must have known about the way sound travels through solid materials and how it is reflected inside them - otherwise hitting a statue would also make other things in the temple swing....Imagine that it was known how to produce the required frequencies to basically weaken the crystal structure of a rock exactly where you want it to weaken.You would have a rock-shaver of sorts.You could not use it though as it would be a huge thing.Theory is the ancient builder worked the opposite way instead.Making the entire rock or even mountain swing at a perfectly matched resonant frequency that produces a peak right where you need to work.A bit like going a dentist that no longer uses a rotating and screaming drill on your bad tooth, instead you sit in a fast rotating chair ;)Lab experiments clearly showed it is possible on a small scale with our modern technology.Tungsten-Carbide already in the ancient world?Electron microscopy claims to have found evidence of substances embedded in the machined surface that have similar properties to our modern carbides.Of course every alien theorists jumped right on it and claimed that had help from extra terrestrials.But is it really as simple as someone coming down from the stars to give some ancient builder a more than modern tool?He wouldn't have a clue how to use it, how to power it, he would need a teacher and power source.What some of these alien nut crackers missed is the simple fact that a lot of really hard materials can be created by the most basic means.Thermite is still widely used and produces quite good steel, all you need is iron oxide and aluminium powder.With sand you can even make your own silicium metal is you like on the beach....Where the knowelde for such things and more originated might remain a mystery but we have evidence the ancient guys knew quite a bit about ores and oxides, so why is it so hard to think they accidentially or intentionally tried to melt them into tools or art pieces?And then suddenly something goes up up in flames and some shiny and really metal appears when cooled down....We also know the ancient people knew about several acids and how to make them from scratch, even how to concentrate them.Not soo hard anymore to create some waste products that are of no other use to you than to be used as grinding materials and abbresives....As said, it is unclear where the knowledge or idea come from, all we know they had the know how.Where did the ancient tools go?We can still find tools in the pyramids in tiny and no longer accessible areas - at least no human fits in there anymore.We also found clear indications of iron oxides embedded in stone surfaces, predominantly in holes and such.So they might have had iron or even steel around the same time we though they only had copper and brass, big deal...Well, it kinda is...Especially Japan showed us how metallurgy is carried on as a vital tradion into todays times.From selecting the raw material for the melting, over the entire melting process, down to discarding most of the results by just looking at them - an understanding we modern people no longer have.And the swordsmith again only takes those sample where he can see already how they work together when he heats them up and hammers them.Especially the secret knowledge how to iclude impurities, remove them and what natural and most basic additions need to be added is something even modern science fails at.A bit of leafs from this plant, some dirt from that region, some burnt wood and suddenly the resulting steel won't rust anymore, is more ductile and hard at the same time...But you would need this kind of attention when you create tools.For steel you want a certain hardness, flexibility or ability to flex without breaking quickly to avoid fatigue.In most cases these steels are anything except resistant to corrosion.Most tool steels of the older days needed to be kept well oiled or they would rust away quickly.Chrome and other hard to come by elements gave our modern steel the stainless effect.From the ancinet world we know of iron statues and pillars that produce a protective rust layer of just a few microns but no further rust damage.You wouldn't be able to create this without generations of experts refining the process and observing how well or badly it works out.Would you take your expensive tools that might taken weeks to manufacture at a job site with thausands of slaves? Certainly not, you taken them home with them and slep with them under your pillow....No surprise then that we could never find any "good" tools around ancient ruins.Once a town is build today you won't find the tools of the tradies still sitting around either...Is this evidence?Nope, the failure to find high quality tools from builders does not mean they existed.Finding evidence of modern alloys or steels just in abbrasesion or tool marks is no good either.It could be from someone at a later time simply following these marks with a more modern metal tools, like a steel needle.For every evidence here there is also evidence of where the evidence can't come from.Again science clashes with archeology and history without being able to agree or compromise to provide a conclusion that is acceptable by both sides.Only materials designed and created to last throughout history will survive thausands of years of exposure to the elements.We might find real and undeniable evidence one day in lost cities on the ocean's floors, till then though....

Topic by Downunder35m  


Removing Broken Pin from an RCA Jack

I recieved a free, working TV the other day. The only problem with it was the pin from an RCA video cable had broken off inside the socket. I didn't want to spend money on an RF modulator for my DVD Player, so I figured out a pretty solid way of getting the pin out. 1.) Find a needle 2.) On a hard surface, bend the very tip of the needle slightly so that it forms a tiny barb. 3.) heat the tip of the needle with a lighter until it glows red hot. 4.) stick the needle into the plastic core of the broken RCA pin 5.) wait a few seconds for it to cool 6.) pull the needle out, and the broken tip should follow!

Topic by spenjmn    |  last reply


Tempered glass screen protectors - understand and beware!

I recently had the joy of needing a new screen protector for my mobile after being dumb enough to drop it on gravel. The hard cover took all the impact but the film protector on the screen was scratched badly. Was old and partially worn anyway so I decided to upgrade to a Tempered Glass screen protector. Being somewhere rural I had no chance to get one in a shop so I ordered online. With no intention of advertising for some sellers, I collected a few links so you can check what I am talking about: Item1 Item2 Item3 Item4 Item5 Item6 So, what is my concern with these? They all can be found on amazon and other online services as well as on local markets... As I said I ordered a glass screen protector. If you check these listings and even some of the packing you will notice they all have a thing in common - being shatter proof and of 9H hardness. I also love this video showing how to remove and fix a glass screen protector! The last time I checked glass had one very distinct feature: It is hard and before it really bends it breaks - unless you use fibre optics of fibre glass cloth... What is my concern and warning here? Pretty simple: Stay away from expensive scams! Some claim their screen protector is only 0.25mm thick, even the 0.2mm one I measured was over 0.5mm with the glue... The hardness of 9H refers to the so called Moh's hardness - look it up on Wikipedia if you like. That means these tempered glass protectors would have a similr hardness than a diamond, or at least close to it. Problem is that they are made from plastic to start with and not glass at all. They claims that the screen protector is flexible because it is so thin - again a fake! Even the thinnest tempered glass will shatter if you bend it enough, not so these plastic ones. If you think I am making all this up try to use a really sharp knife or deburring tool and cut the thin sides of one of these protectors. All the ones I tested could be cut quite easy - and I though glass can't be cut with a kinfe... A nice website showing that the scratch resistance is far from the claims can be found here. And a video showing how a real glass screen protector sounds and breaks can be found here. So is it really all bad and should I avoid getting one? Not really if it is only for the added protection. To be clear here, and without the intention to blame any of the above sellers, some protectors actually do have a top layer made from glass and you can hear it as in the above video - it sound solid and not like plastic if you tap it with something hard. Another factor is the simple fact that plastic absorbs impact much better than glass. So where a real glass screen protector might shatter and crack like in the above video, the fake ones might one get a nasty dint or scratch. But you should be aware and clear about what you get and what to expect from it. These glass imitations are made from a strong polycarbonate plastic, similar to the stuff used for bullet and explosion proof "glas" windows - if you every watched the Mythbusters you have seen the big sheets I mean. The top layer of these things is specially treated to repell water, oil and dirt, it also gives the surface the good scratch resistance. The technique is nothing new, camera lenses, plastic sheets and the clear covers you see over the timetable at your bus stop all use it. The new thing is to intentionally mislable a product to make the consumer think it is glass ;) What is the real difference for the user? Check this video. Here a guy performs a drop test with a real glass screen protector. Thing is once the protector breaks the screen itself is broken too but until then it was not too bad. Here it is demonstrated how a real glass screen protector reacts to certain types of abuse - one of the reason I decided on glass. Compared to the plastic counterfeits just the sound on the glass is worth it, but I think the hacksaw was best. Another video from XDA gives a bit more info on how the glass is made - if you can't seeing a phone being abused then don't watch the drop tests at the end ;) Glass with these hardness levels and types of surface protection will give the user a long and worry free use of the phone. The plastic fakes will perform at a similar level for some time but will show signs of wear long before even the top coat of the glass one fails. Both types have their uses and if the fakes would be labeled correctly the user would actually benefit from that. On bigger screens like a tablet I would actually prefer the plastic ones to prevent damage once it needs replacing. On a mobile used in less than perfect conditions I would also go for plastic as it usually is a bit thinner and will fit better within quality hard covers. But when it comes to real abuse like using with dirty fingers most of the time or mostly outdoors where a lot of dust and fine sand can be involved I always go for glass. If you paid attention to the surface treatment then you already realised that the plastic and the glass are in the same region, making them quite scratch resistant. Still fine sand or metal dust will scratch it.... The difference is in the hardness of the actual material that was covered with the oleophobic film. Glass will not give in any way, where plastic is much softer - so not to be confused with the surface hardness! This mean that sharp and point object will easier penetrate the plastic than the glass, something to be considered if you often ecounter harsh use. In terms of actual protection we need to differenciate between surface quality and actual screen damage. After all when badly scratched we can replace the protector but if the display got damaged we are back to square one. The surface hardness was already covered so let's move on to the screen itself. In some of the above videos you can see the abuse a screen might see in normal conditions, and if we would not drop our phones so often repair shops would not be at every corner LOL I have done quite a few screen repairs, mostly for friends and work mates that did not want to pay the hefty extras in a repair shop. From there I got the stories on how it happened and in almost all cases the screen cracked when the phone landed on the corners. In one case the screen and glass protector failed, including the actual display when the phone was dropped out of a 4WD and landed screen first onto a rock. A glass protector will spread the (direct onto the face) impact force onto a much larger area, where a plastic one will produce a dint onto the actual screen much sooner. So again glass wins in terms of actually protecting your expensive screen. But be aware that all this is useless if the phone lands on the corners!! Let me explain: Both the top glass on your screen and the screen protector have a thin layer of "glue". This acts like a shock absorber, so unless an impact goes deep enough so the pressure on the actual screen is too much only the protector should fail. But the screen itself is a tight fit into the frame of the phone, so all side and corner impacts go directly into the glass. As the rest of the glass has no way to give or go the stresses will crack the screen. How should I treat my phone with the new screen protector? Exactly the same way you would without it of course. But if you don't have a proper cover that offers protection of the corners you should invest in one. Having a quality protector and a good case does not mean your phone can be used as a football, see it as an added insurance in case something does go wrong. For obvious reason it can also pay off to have a spare at hand, if something bad happens that requires replacement of the protector you won't be left with an unprotected screen ;) Last but not least, double it up: For people that already know their screen will see a fair bit of abuse in term of scratches it is a good idea to put an extra film protector onto the glass one. Once it is too scratched you peel it off and replace it, while the glass protector gives you the actual protection for your screen. Corning Willow glass As time of wrinting Corning Willow glass is the only "flexible" glass on the market, unless stated with your flexible screen protector you can assume it will be just plastic. I did not list it above as this high tech material is mainly reserved for displays and at least to my knowledge is not available for screen protectors, although I will stand corrected as I have to assume some big players use it for their protectors. The material is actually a sandwich where an ultra thin sheet of glass stis bewteen two layers of durable coating, read it up on their website it is quite interesting. It won't reach the strength of their famous Gorilla glass so without an outer plastic that has the additional oleophobic coating it won't provide the strenght of real tempered glass protectors. Some phones like the Galaxy Round and the fleixble HTC phones use it for example.

Topic by Downunder35m    |  last reply


Tips and Hints

This is my invention for the day.  Use of magnetic tool holders is a very old, but handy way to organize tools.  My contribution to Magnetic Tool Holders is to use small, strong magnets (12 mm diameter) attached to a metal bar or in the photo, to my card table edge.  That in itself is still not very significant. However HOW the tools are hung from the magnets is significant. The problem:  If I put the magnets vertically and hang the tools vertically, the surface area of the magnet is such that often the attraction between the tool and the magnet causes the magnet to stay with the tool instead of with the table.  A magnet sticking to the tool, can be very annoying. The solution:  Placing the magnets horizontally--at the bottom--AND hanging the tools by their tips allows for very easy detachment and attachment.  The magnetic force is strong enough to hold some very heavy tools, like the pliers or long nose pliers without any difficulty.  The tools are easily removed and easily replaced.  This would also apply to any magnetic strip.   The key thought of the day: Hang tools from magnetic tool holders by their tips. Of course, another solution is to glue the magnets to the supporting bar--wood or metal--and clamp the supporting bar to the table.  That works as well, but is more permanent and is a little more work.  Also, if the magnets are allowed to attach by their full surface area to the tools, the tools are hard to remove.  

Topic by stannickel    |  last reply


Small VERY Hot Plate

I am looking for someone who can design for me to make or make for me a specialized hot plate. I need it to be small like 3" by 2" and to get very hot as much as 700 degrees is desired. I want the power source to be 400watts. I know this seems hard but my reasoning is that the smaller size means higher temps with less wattage. I would use this as a hot plate that evaporates liquid from an airstream as it passes by - a dryer if you like. I would use 2 to cause the air to have to pass both in a zig-zag path. I would like to have a solid surface so eventually I see the plate encased in ceramic but for this it need only be metal. Can you help? Contact me here on the site to discuss more details Coog

Topic by coogrrr    |  last reply


Question about the full-screen teleprompter?

 I made a quick teleprompter based on yours as a guide, but made mine from black foam core instead of wood, and it's as strong as can be (and acts as it's own blackout device because it reflects very little light. And it works awesomely except for one thing. The glass on mine (just regular picture frame glass like yours) reflects a double image back at me, I presume from both glass surfaces. How did you manage to not get a double image, which on mine makes the text really quite hard to read. I was thinking of going to a glass shop and replacing it with a piece of one way glass, but you used regular glass and apparently have no problem. Just wondering if you know why or have ay explanations for me on this. Thanks,

Question    |  last reply


Thickening enamel paint. Answered

I am looking for a way to thicken enamel paint to a buttery consistency similar to the acrylic paint you get in a tube. I worked out a decorative effect years ago which uses acrylics and is good for painting tins, but was never hard enough to last well. The only thing I could think of was ground glass, but I'm not sure if you can buy this as a hobbyist, as it used to be used as a poison. (If you're curious, the way I used to do it was to lay down a layer of acrylic in one colour, pick up the surface with a brush to make it stand out, wait for it to dry, then put a contrasting colour over it, and when it is dry sand it with wet sand paper until the colours from below stand out. It makes a marbled ripply effect which looks pretty e.g. in purple and orange).

Question by ganglion    |  last reply


Other uses for a Caramel Wheel....

I had to clean up large sized decals that used a 3M adhesive.Instead of filtering the solvent fumes with my lungs I decided to listen to the guy in the hardware store that suggested to use a Caramel Wheel instead.Have to say I was very sceptical...Ever had this extra heavy duty 3M tape to get off again??No matter what you try it is a battle of will and endurance...To my surprise using the Caramel Wheel was like using a big eraser on paper.The things rubs over the surface, takes the goo off and leaves a totally clean and stick free surface.What otherwise took me at least a full hour was done in under 10 minutes - great...Once done with the hard work I examined the now well used up wheel.Does not really work as a proper eraser for a pencil as the rubber is much harder.Does not even scratch galvanised surfaces.Does not like it at all to be used on wet surfaces :(It is not just rubber in a fully solid form, more like flaky bits stuck together.First misuse I tried was polishing a piece of acrylic plastic.A cloth or similar always soaks up a lot of the polishing compound, which makes the process costly.Friction was a real issue at first because the wheel just had no grip at all.But on hindsight it helped to spread the compound fine and evenly.When it started to grab I noticed two things.a) The plastic warms up quickly.b) It polishes really good.Downside is that you need a low speed and very little pressure, too much of either and you risk stripping off the surface.Second misuse was on my knife.It is old, it is abused, it is loved tool I prefer, so it does not need to be razor sharp.The burr on the knife edge after sharpening should be removed.Usually I work my way up to 1000 grid, then use a leather strop.Not for this old knife though.In most cases the burr comes off with use.The Caramel Wheel had no problems removing the burr while leaving the edge sharp.And with a tiny bit of polishing paste applied it even managed to produce a extra sharp edge.Last misuse so far was to clean off old silicone from my bathroom tiles.Silicone does not like to stick to silicone!Means when you refurbish for example the silicone around your bathtub it never last long.Chemicals to remove the fine layer of silicone are harmful to say the least.I did not bother with the entire groove, just the outer parts where the new silicone needs to grab.First the wheel slips and slides off a lot but you see how it cleans the surface of the tiles.Then it starts to grab, indicating the tile is clean in this area.Won't do much in the grooves with the grouting though...What I really liked is that the wheel took off what you can't really see.The oily feeling when going over removed silicone was gone, just nice grippy tiles.

Topic by Downunder35m    |  last reply


Gaming without the disk?

I know there are instructions all over the internet on how to do this but as far as i can tell the instructions are without the original disk, if i have the original disk is there a way to download all the information to the computer so that i can launch the game from a folder? a way that doesn't make punkbuster (EA games) kick me if i play online. essentially i want a digital disk so i can use the original as a backup and i won't have to worry about my family removing my disks and destroying them (they tend to leave disks anywhere they can put them down). As a random note im always worried that when transfering my disk from the case to the drive that something will happen as in the past i have been pushed and i dropped the disk, it landed on an uneven surface and someone stepped on in breaking it.

Question by pmk222    |  last reply


Soldering aluminium and stainless steel - input for an Instructable

I am currently working on a new Instructable covering the topic of soldering aluminium and stainless steel. As I am "old school" and don't like to waste money on special equippment unless really necessary, I would like to get some feedback on what to include. So far I covered the basics of the materials, the general how to and what to llok out for. Pics and videos will be made once I am happy with the tutorials to give a better understanding. Aluminium is considered to be hard to solder with no experience and I would like to try to make it possible for the hobbiest to do it, same for stainless steel. For example: Should I include my recepies for stainless steel fluxes or limit it to the procedure of actually doing it without any flux? Is is better to document with nice pictures or videos showing the entire process? (asking the noobs that want to learn it) Is it necessary to go into details like what solder alloy is best for the purpose? For me it is quite hard to go back to a "I know nothing about it state" and make sure everything a noob might need is included. But the longer I work on it the bigger the Instructable is getting with informations that not everyone might need, like how to properly clean the surface, remove the oxide layerand provide the right temperature for the job. Trying to keep it simple but complete and not drifting into boring details is harder than I tough on this topic :( Feedback and requests are welcome!

Topic by Downunder35m    |  last reply


I need a circuit to run a tiny motor from a USB port? Answered

I made a leather "Steam Punk" case for a portable hard drive. It has several gears that show under a glass porthole and I need a way to move the gears powered from a second USB cable. I'll use a separate USB cable then the Hard drive as I don't want to compromise the original device. I have a very small motor from some Radio Shack ZipZap RC cars. Tried to design a simple circuit myself but can't get the motor to spin. I suspect it doesn't have enough current. The motor does spin if hooked directly to a AA batery. The ZipZaps work with 2 AAA bateries in the charger/controller. The car hooks on top of the controller charges up and then can run for a short time. Opening the car up it has a 1.2 V 100mAh NI-MH battery inside it. Tried looking at a couple of BEAM robot solar engine designs used to run small motors from solar cells but just coudn't figure out how to convert them. I'm looking for a small circuit (in size) that could drive this motor, with a backwards current spike protector so the USB or computer doesn't get fried. I have limited EE experience but can through hole solder but not surface mount. -Steve

Question by nevets_mcd    |  last reply


The more natural way of cleaning things...

At my workplace we basically have a specific cleaner or cleaning product for every task you can think of. From glass over stainless to plastics and desinfectants for lots of different surfaces. After a quick look into my cleaining cabinet at home I started to wonder if I am doing something wrong as I only have a few cleaning things for my use. Asking my friends also showed they have a big bunch of cleaning chemicals, plus the bottle of bleach that everyone down here has. So I though: Your grandma only had a few cleaning products and you learned most of things you need to clean from her. Considering I grew up healthy I guess she must have done something right.... Let's clean up with the cleaning myths, shall we? 1. What cleaning chemicals do you have? For quite a few people the list would start something like this: Dishwashing liquid, window, cleaner, bathroom cleaner, soap scum remover, floor cleaner, oven cleaner, several desinfectants.... If that is true for you too than we might be on to something already. 2. What cleaning chemicals do I really need? This is a good question as everyone is a bit different but I assume a healthy household here. Of course we need certain things to clean our various surfaces properly but it is far less than waht you have been told by the TV commercials.... These days we like to think if there is a special cleaner for something then of course we have to use it to clean properly. Unless you have trades people walking through with their wet dogs several times a day and see dust storms at least twice a week you really only need a few things. So let's get to the basics: 3. Old style cleaning and what you need for it - really the only stuff required to keep all clean and sanitised. a) Methylated spirit b) Clear ammonia - cloudy ammonia works too but be aware that the added soap can be a problem that leaves streakes c) Hydrogen peroxide - pool grade to be cheap in the long run d) Orange oil - citrus oil works great too if you prefer a different smell e) Soap - just basic soap, these stinky, slightly yellow and hard bricks - no fancy smelly soap ;) f) Several cleaning brushes but you should already have those g) Windows cleaning tools - the basic microfibre cloth and squeegee will do h) Several microfibre cloths - bigger ones for floors and walls, smaller for windows and the rest I) Yesterdays newspaper j) Baking soda With those few things we have everything to clean whatever comes up and if bought in bulk comes down to a few cents per bottle compared to a few dollars when you buy all the stuff you don't need. Lets figure out what the stuff does and how to use it: 4. Mixing and what to use it for.... The alcohol is a really good remover for everything greasy and also desinfects the surfaces. A quick spray and wipe on your bench is all that you need to remove oily residue or the mess from the kids. Mixed with a bit of soap and water (about 50-50) also removes sticky stuff like jam or syrup. If we use about 50ml of alcohol, 50ml of clear ammonia and 900ml of water we get one liter of really good window cleaner. The modern way is to use microfibre for the cleaning and a squeegee to get it dry, the old way just uses a cloth and then the window is "polished" with some old newspaper. The black ink reacts with the alcohol and form a mild abrasive while the paper soaks up the moisture, the result is a prefectly clean window in under 3 minutes. Orange oil is not only a powerful degreaser but also lifts old dirt or even glue residue. Used directly it will get rid of the remains from sticky tape, stickers and everything that other cleaners fails to get off - smoth surface and non soaking of course. 50ml of it with 50ml of ammonia and 100ml of alcohol per bucket makes a good florr cleaner and your house smells nice when done. Works best if you can use a microfibre cloth or floor wiper to dry the surface with it. In the kitchen we can find a lot of surfaces that are greasy and we already covered that bit, so lets get to the though stuff. The kitchen sink can become dull looking although it is not scratched. This is due to hard water, food residue, soap and other things. Best is of course to wipe it and dry it after use but who really does this every day? A pot scrubbing pad with some baking soda on it does the trick here. Make the pad nly moist and sprinkle the baking soda on it. Rub over the stainless and if too dry add a few drops of water. Once done rinse off and enjoy the difference. For hard to clean or badly turtured sinks you can try a ball of aluminium foil and coke - use it like a polish. The oven is often our worst nightmare. The cooktop is not far behind. But even here we can have a chance to clean without too much hard work or bad chemicals. Of course the best way is to prevent these spills and boil overs ;) For the cooktop some hot water and baking soda will soften the baked on stuff. Simply remove what you can with the hot water and then sprinkle the surface with baking soda. Cover all with the paper towels and if not wet enough add a bit more hot water so all shets are soaked. Leave ove night and wipe clean the next day. The oven is a bit of a problem once the side and back wall are filthy. If baking soda with a pot scrubber won't do the trick get some of these steel pads with soap in it. The soap in them is special in terms that you only need a little bit of water to remove almost anything with them - and they won't scrath enamelled surfaces. On the bottom we often have badly burnt in things that are next to impossible to fully remove. I suggest to cover the same way as the cooktop but also to add some orange oil. Just make a thick paste of baking soda and orange oil and wrok it into the soiled surface. Cover with wet paper towels and leave over night. Now you don't want to flood your oven, so that means you need to use a sponge or thick cloth that is big enough to wipe off the surfaces you soaked the day before. As the orange oil really is oil it pays off to use some alcohol in the cleaning water to get rid of the oil and grease a bit easier. Don't expect to see a clean and shiny surface after one treatment if the oven was badly misused, you might have to repeat the procedure a few times. If in doubt use the soapy steel pads for last clean and before soaking over night again. Three to four treatments are usually enough to clean even the worst disaster that can happen in an oven unless you baked it in for months... 5. Desinfecting and mouldy spots.... As said, the methylated spirit is basically just pure alcohol and kill almost anything that might harm you. But sometimes that just is not enough. And who really wants to spend an hour or longer to clean some mouldy spots in the shower or try to cover the smell by spraying room freshener? As a lst resort for everything I use Hydrogen Peroxide. The supermarket grade is only 3% and usually badly overpriced, so I suggest to get a small canister of pool grade peroxide. Do yourself a favour and ask them to install a tap on it - you don't want to do it yourself unless you already know how bad pool grade peroxide is! For your own safety when handling it I strongly recommend wearing long rubber gloves, nitrile is better but please no latex as it could start to burn when getting in contact with the peroxide. For high grade desinfecting or the removal of mouldy areas I recommend to dilute 1:5, one part of peroxide to 5 parts of water. Only for the mould removal on tiled, plastic, glass or metal surfaces you can use the peroxide pure from the container - but please add face protection when cleaning! Some spray bottles work with peroxide some just start leaking badly, if you want try an old bottle of chlorine based cleaner after really flushing everything out. The peroxide breaks down any organic material it comes into contact with, so not just the mould you want to remove but also your skin or eyes if you allow contact. On the skin you see white areas after contact and they won't go away until all the oxygen in the skin is gone that was left by the peroxide. If you act too late it means you might loose some skin flakes. The sure sign of overlook exposure on your skin is a burning sensation in the area - this only happens when the amount was big enough or your clothes got soaked. On your surfaces to clean you will notice bubbles forming quite quickly - this mean the peroxide is reacting with something, usually organic material. Let it bubble... Once it stops bubbling the surface is either sterile or the peroxide is used up, if it bubbles when adding fresh peroxide onto it then there is still crap left ;) It really helps to brush off the surface after each treatment as a lot of loose material will be flushed out when rinsing off. Once it looks and smells clean again it usually means it is clean :) 6. Special case: Wood... Be it wooden floorboards, furniture or just your chopping board - always try what the manufacturer recommends first! Untreated wood should never be cleaned with anything wet! Sealed wood, like floorboards or things with varnish on it to make it water proof can be cleaned the same way as mentioned above - but I would leave out the ammonia as some wood treatments simply won't tolerate it and might go dull instead of returning nice and shiny - spot testing required if you think you have to use ammonia as well! Orange oil itself makes a great furniture cleaner if the surface is smooth and sealed, but if it is not it means the oil soaks into the wood together with the stuff you want to clean off! It also takes off several paints and types of varnish if you work it hard enough and give it some time, so avoid this and be quick instead of forgetting to finnish the job ;) Always try to wet the surface as little as possible and wipe fully dry as soon as possible! Ok, good start but what is the real benefit? For me the actual benefit is that I know what I am using and exposing myself to. Just reading what is in most cleaning products we find at the supermarket makes me want to clean again after using them, just to remove their residues... I admit it might take some time to get used to mixing and just having a few ingredients for the cleaning but it does work great. Especially if you or your kids are already sensitive to certain chemicals or just of poor health in general you might see the benefit quite quickly. Some people really don't like the smell of ammonia but unless you are sensitive to it there is nothing to worry when using the household grade as we always dilute it down massively anyway. A good way to avoid the worst stink is by mixing it outside with the wind from behind. I won't say that certain commercial products are bad, harmful or not good enough for the job. Some are actually worth to have in some cases but I just say it is better to only have a hand full of chemicals that are not too bad instead of an endless list of things were we don't even know what's inside. For me the best is your surprise when it actually works better than you expected and report your findings here.

Topic by Downunder35m  


how to make a rubber part that doesnt exist ?

Hi good peoples, i work at a place that makes and sells beef jerky and smokies. quite recenty one of the machines we use to cut them from links quit working properly and needs a new rubber pad for the clutch that stops the blade. the problem is the company we bought the machines and all parts for them it died with the owner so we cant replace them. my question is how hard would it be to mold rubber into a new brake pad for the clutch. i will put up pictures of the clutch and pad as soon as i can but i might as well start with the first problem how to cast and mold a rubber sturdy enough to do the job. all info on this would be greatly appreciated side note: now that i have the parts this is what they look like. two very soft rubber wheels with a concave treaded surface. the rubber tread is really worn down hence the need for replacement 

Question by snowfox222    |  last reply


Can countertop laminate be used as flooring?

I've been having a hard time finding just the right color and pattern that I want in sheet vinyl or tiles, and Formica/Wisonart laminates come in about a BILLION styles and colors. If I put it down as flooring, do you think the surface would last over time? In a bathroom it would only see foot traffic and water, nothing heavy to scrape or damage it (like a fridge or furniture legs). I don't imagine it would chip or break as long as all the outer edges are protected. In a small bathroom you could get away with using only one sheet (no seams), or 2 sheets with just one seam in the middle. Sheets of laminate aren't cheap, but they're no worse than sheet vinyl of the same size. I imagine you couldn't "loose-lay" it even if you cut it to the exact dimensions of the room, because you'd probably get a slight air pocket effect when you step on it. A strip of glue down the floor's center along with perimeter gluing ought to be sufficient.

Question by Scott153    |  last reply


A little magnet experiment for everyone!

Some people just love to play with magnets and have a lot of them.If you are just like that and like to tinker a bit then I might have something for you.What magnets you use for the following experiment does not really matter but you should have 20 or 30 of identical properties.Can be disk magnets, block magnets or cubes, just not spheres ;)If you have a 3D printer you use it to make it fancy but a peice of wood, acrylic or such and a drill will do for round magnets.For cubes or flat packs you can make retaining walls on a flat surface.The experiment goes like this:I assume you already tried ways to combine your magnets to make them stronger, like stacking them up.But there is another way to really increase how strong they are combined.Start with one magnet at the center.Then like a ring add more magnets around it but with the oppisite side up.The created mounting solution is to prevent them flipping up and together, you want them as close as possible though.Add another ring and change the direction of the field again.Try this magnet, once all magnets are secured and compare the holding strenght to any other combo you tried so far.It will be much higher for the same amount of magnets.If you want to prevent the use of glue then try to create your mounting system with a really flat but strong enough bottom - this will then be the contact surface.Slightly reduced strength but you can re-use magnet with ease.But if you want to get a really strong one you need cube magnets.Like before you want to create some sort of grid, this time we go for a square.Start with cube in the center, facing north up.Leave enough space in your construction to add 8 more cubes around it - like on the face of a rubik's cube.Leave them empty for now !Add nother row, this time 16 to keep the square.Of course these one go with the south side facing up!Again one empty of 48 and then one last one with north side up with 196 magnets.Ok, to be fair, you wouldn't be able to pull it off a metal surface unless you used really tiny cubes, so if in doubt then go for just to 48 and leave the enter one out for now.Should be quite intense but similar to what any other shaped magnet would have done.Time to fill the voids!Add the cubes in the spce between the magnets so the north and south side face the magnets next to it!So basically sideways but in the correct orientation.You can then also add the center piece - try either orientation for that one ;)What happened now is that you forced the magnetic field lines to go up instead od for trying to go the easiest and shortest way to the next magnet.And "up" is where our magnetic surface would be, which provides the now overdue shortcut for the magnetic fields.Be amased how much stronger this version is and how much even 3x3x3 cubes would accomplish.With 10x10x10mm N52 magnets you might be able to use them support our wieght if you pull straight dwon from a horizontal surface...Ok, kidding, not just might, unless you are really big...One 10x10x10 might hold about 6kg.Stacked up a bit more but having 20 or stcked up would not be much stronger than 10.Even just 25 magnets with one in the center, one row of sideways orientated and one row with opposing field to the center one would be hard to remove from a steel surface.If we go with the imagined 6kg per magnet we could assume to get 25 x 6 = 150kg of holding power.Check you single magnet first then compare to the square of 25 ;)Consider using some plastic between magnet and surface so you can at least slide or pry it off if you have to.You can also combine magnets or a new one that has one side appear much stronger than the other.Meaning that for example on the north side it could hold 20kg while on the south side only 5.

Topic by Downunder35m  


"Sonic" drilling or cutting

If we look up sonic drills today we usually get some fancy machines driving pipes in the ground, preferably softer ground.But the term includes all types of machines that use sonic vibrations to advance through a media.With the ancient and claimed to have never existed technologies in mind I did some digging...In the food industry vibrating knifes are quite common, same for "air knifes" on softer food.Even in the meat industry they find more and more uses now.Ultrasonic cutting or welding is the same thing and included in "sonic".Same for some experimental sub sonic drilling methods currently being tested.The general idea might be as old as using vibrating equippment to compact stuff, like concrete, bricks and so on.What you can compact by vibration you can also make "fluid" by vibration.Industrial feeder systems utilise this to the extreme by even making light and fine particles like flour move like water without causing any dusting.What all the techniques have in common that a suitable tool or tool head is used and that it is attempted to use the most suitable vibration frequency for the job.Anyone operating an ultrasonic welder knows the pain of finetuning for a new electrode or just new part to be welded.What does that tell us now that makes the understanding easier?Take a bottle of ketchup, preferably one that is still quite full.Turn it upside down and noothing comes out.Shake it a bit and you are either lucky or drowned in red.But hold it at an angle and start tapping it and the red sauce flows out easily.What it true for most newtonian fluids is in some way also true for non-newtonian fluids.Ever mixed corn starch and water to make these funny experiments with it?Hit it hard and it reacts really hard and is not sticky at all.Leave your hand resting on it and in sinks in and sticks to it.Stirring it very slowly is easy, go faster and you get stuck.You can do similar things with by using an external source for vibrations.For example a vibration speaker mounted to a smal cup of the goo.If you place sand on a sloped piece of plastic or sheet metal then at a low angle it will pile up easy and stay.Start vibrating the plate and the sand will start to flow off.Works fine with a vibration source mounted to a piece of steel bar or rod and a bucket of sand too.Trying to press it into the sand requires a lot of force, especially once you are a bit deeper.Let it vibrate properly and it slides rights down.If we can do the simple stuff as well as really complicated stuff in the industry then what about other materials?So far we use vibrations to make things move out of the way, compact things, transport them or to heat them up for welding plus some cutting applications.Considering the variety one might wonder why no one tries it for "difficult" materials.Machined surface can be found throughout ancient history.Finding "machined things" were vibrations was clearly used is a bit harder.The great walls are not a perfect example here as the views differ quite a bit on how they could have been created.But if we leave things melting them or a secret concret like recipe for creating for example granite then vibrations start to make some sense.You find some interesting videos on youtube where people use speakers, wires and rocks to confirm you can actually "machine" them by vibrations.Especially granite has some quite musical properties, big boulders as well as smaller ones produce destinct sounds when you hit them hard.Tests and measurements were made on granite and other hard rocks to check how fast sound travels in them , how it is refeclted and where the sound comes out or affects the surface the most.Lets just say every sample gave different results.Shape, density and dimensions affect not just the resonant frequency but also where and how the sound travels in the rock.What if??We can use a simple speaker, a plate and some rice to see how patterns form under various frequencies.Works with sand or other granules as well.The interesting patterns are the so called harmoncis.Here we see clear and destinct patters, sometimes with extremely fine lines and areas of softly vibrating granules.Some people say these harmonic frequencies have all special meanings and uses.We mainly used them to avoid problems.Imagine your new TV would not have a housing tested to be stable with all frequencies the speakers can produce.All of a sudden your back of the TV might start to rattle ;)Same for car engines.Harmonic vibrations are eliminated wherever possible.Otherwise they could multiply and affect other things in the engine or around it.Simply put it means we have various options to detect and measure vibrations on a surface or in a system.Back in the day every half decent backup generator had a mechanical indicator for the frequency of the supplied electricity.A set of tiny forks with the desired on painted red and several on either side of it.These forks were designed to get into harmonic and therfor quite intense vibrations at their set frequency.If the one for 50Hz looked blurry then all was good ;)The same principle god be applied on a big boulder of granite.Place the "vibration meter" at the desired spot and start moving around the vibration source on the surface until you find a spot that causes maximum response on the meter.Best thing here is that if you then place that surface area onto another peice of fixed in place granite both pieces will start to loose substance if vibrations are applied.The fine sediment forming is then usable as an indicator where to move the vibration source to continue once the effect literally wears off.Is it feasable?Well, if we trust mainstream science then the answer is no.A huge amount of vibration energy would be required for such a hard material, despite ancient proof that says otherwise.Semi industrial test also seemed to confirm the theory as only with very high amplitudes (loudness) and while automatically adjusting for the resonant frequency changes a measurable amount of material was removed.I struggle a bit with that as for the testing tool heads made from hardened steel or carbide were used.And that with little or no regards on how the head and tool itself affects the output.I mean in terms of having the max possible movement happening right t the tool contact surface!There is a huge difference between applying a vibration to a tool and using a system, tool and tool head DESIGNED to work at the desired frequency!Otherwise we wouldn't need a computer to design and test a horn for welding purposes or shade a knife spefically so that the vibration go along the right axis and in the right direction.You not break a hard thing with a very soft thing unless it travels fast enough to become harder as the target!This complicated explanation basically just confirms that if you hit water at a too high speed then it will just break you into pieces instead of offering a soft splashPlease do not jump of bridges or such to confirm this yourself!!If that is really true and science says it is, then how about the other way around?Works fine too, or we wouldn't have pressure washers or water cutters.Now for the part where I hope some really smart people leave helpful comments:If we can cut steel with just a stream of water, then I ask:Isn't for example copper much harder than water?Steel is much harder than copper but water cuts through it.The answer here it simple or complicated, depending on how you want to expain how it works.Comes down to speed and pressure plus the right nozzle shape to prevent a beam expansion.But then water is indeed "harder than steel".Questions:Lets say we would use a copper pipe that in lenght, thickness, hardness and diameter is optimised to transmit a frequency so the pipe end sees the max vibration like a feed horn for ultrasonic welding.Not to hard to calculate these days :)Now imagine said "main frequency" would be optimised for the pipe but also be a harmonic frequency of the rock to be worked on.The pipe end would deform quickly, abrasion does the rest and it fails before even making a decent sratch that is not copper metal on granite.No matter how hard we press nothing good enough will ever happen.BUT: If we would add more hormainc frequencies to feed our pipe we can multiply the amplitude quite easy!Just try with a sound generator from your app store, needs 2 or more channels to be usable.Pick for example 400hZ on one and 800Hz on another, then finetune around these number to hear how the tone changes ;)My theory goes like this:If all "working frequencies" would just harmonics of the resonant frequency of the granite, then they can be tuned so the effect on the pipe end is minimised.The overlaying frequencies however should result in the same effect a water cutter has: The pipe becomes ultra hard.The better the match and the more you have to get it right the harder the pipe will be.Adding now a "drilling frequency" or multiple could be used to drive these harmonics slightly out of phase.Like with the sound generator on your phone we end up with a pulsating sound, or vibration.While the pipe still vibrates at the same "hardening" mix the drilling frequency creates a peak like a jackhammer.Try it by using the heaphone output on a small speaker and placing some light and tiny things into the cone.The will violently jump around during these pulsing tones.For a drilling system the output can be mechanically maximised by utilising a pitchfork design.A head holds the vibration speakers and the tynes are tuned good enough to the frequency of the speakers.Always two would have to operate in sync though as otherwise the pitchfork movement that transfers the sound down the center bar won't work.This head could then be desgined to act as a holder for a quick change of work out pipes that are no longer long enough for tuning.I guesstimate that a well tuned design would result in a copper pipe being able to drill at least 10 to 15cm into solid granite before it wears off too much.And we are talking here about just a few mm to get the thing out of tune!But would dare to desing such a thing just to confirm a theory that no one ever really dared to test? ;)And if friction welding works as good as ultrasonic welding, then what would happen if we try this with the right frequencies and vibrations instead of wasting tons of energy?

Topic by Downunder35m  


Ultrasonic cavitation as way to create impossible alloys?

I played around with ultrasonics now for a while and noticed that when it comes to certain things then logic seems no longer to apply.In the normal household you might find some ultrasonic cleaner and that's about it.A few people might have some distance measuring device or sensor array somewhere.As far as the normal human is concerned that is more than enough ;)Playing with certain metals like Bismuth or Gallium is not only but also a nice way to create nice alloys that you can play with even more.Take a portable and simple hydrogen supply as an example.Just make an alloy with lots of aluminium and a small amount of gallium.Cut it into strips, blocks or grind into a powder if you dare.Either way you just add water in a sealed container and get lots of pure hydrogen.The waste product is aluminium oxide, which has additional uses.The gallium itself is not affected by the reaction and can be reused many times.However, with some metals things are just different.As you might know it is hard to impossible to create certain alloys and other wouldn't make any sense.For example an alloy made from Calcium and iron...One of the big problems with alloys is that you need to have both metals in a molten form, then mix them properly and hope it turns out as planned.And well, if the metals in question just on't want to combine we cheat by using slats as a flux for example or by blowing hydrogen through the molten mix to act as a sacrificial binder until the metal cools down.Through ultrasonic cavitation we can not only clean surface, the same effect also destroys cells as the power from the implosion and the intense heat is more than what a cell can handle.There are even tests now to determine how safe and effective it would be to sterilise hospital equippment.A few seconds in an ultrasonic bath would safe the hours in the autoclave...On an industrial scale ultrasonic vibrations are used to weld plastic parts - like the head and tail lights on modern cars or just sealed plastic housings of any kind.With all this in mind my experiments with ultrasonic soldering made me wonder...Science papers state that that for example ceramics are not actually soldered.Appearently it is again hydrogen bonds provided by the ceramic or trapped air inside that provide the means to stick permantly.There is also an effect based on the implosion of the cavitation bubble.Here the solder literally is shot at well aboce ultrsonic speeds onto the surface of the ceramic.Together with the vacuum effect the solder is then pushed into the tiniest of cracks and cavities.Surface tension and other effects finally prevent the solder from just flowing off like it would do if we use just heat.What it means is that there is no real soldering at all happening.In reality it is like millions of big hydraulic presses would push the molten metal onto the surface.Going back to the fun of Gallium with Aluminium....Aluminium does not really go to well with steel.And gallium does not that good with steel either.Melting an Aluminium-gallium alloy is quite simple.With an excess of Gallium in the mix it should be possible to add fine steel powder (steel, not iron!).Of course it would neither mix well nor really melt at these low temperatures.With ultrasoic cavitation however we could force the stuff to not only mix but also create the same effect as used by ultrasonic soldering.The additional metals and minerals in a steel alloy should hopefully prevent any unwanted reactions in the final step...If the steel powder is ine enough then the assimilation of the steel into the aluminium-gallium mix would result in the breakdown of the steel.Once cooled and hard again the big question what would happen if we let water attack it?In theory all aluminium would react to form aluminium oxide and aluminium hydroxide.The gallium again would not be affected and as it is also bound to the steel should form a nice gallium-steel alloy.But what hapens to the voids where the aluminium was???The alloy would either be only affected on the surface or through cavitation and time all aluminium would be transformed.In the best scenario we would get a steel-gallium sponge where the voids are filled with alumium oxide.Forging such a mix could result in a ceramic steel..... !?? ;)Imagine a safe...There is always forceful ways to get in.Like drilling or using a big angle grinder.The pro might use a magnesium torch rod though....The common approach to improve penetration resistance is by filling a space between the outside and inside walls of a safe.Whatever you can imagine that is nightmare for your tools can be used, like thick glass plates, hardened steel bits, carbide studs, concrete with glass fibres....But even diamond tipped tools would already struggle if the steel itself would contain high amounts of a hard ceramic like aluminium oxide.The remaining gallium would also cause very high friction and through this heat - which these tools really can't stand unless you can provide water cooling as well.With the right balance of aluminium and gallium most of the original properties the steel had can be preserved.Just and idea though....

Topic by Downunder35m  


illuminated ball - remote switching and charging

I'm working on making an illuminated ball for playing bike polo with at night time. A couple of high output red LEDs are sufficient for light to get through a normal street-hockey ball. The problems I'm currently facing are switching the lights on or off, and charging the batteries. Ideally both of these could be done remotely - i.e. without having to open the ball up. For switching I was thinking of using a magnetic reed switch - when a magnet is attached, the lights switch off. The only problem is that reed switches seem to be (a) made of glass (not ideal when the ball gets hit really hard), and (b) in a normally-open configuration - I'd need a normally closed one for this. As for charging, I have two ideas - one is to have two small metal pads on the surface of the ball to connect to the charger. This could be problematic due to forces on the ball during gameplay. The other more fun idea would be inductive charging. Like what you get in those fancy electric toothbrushes. One coil inside the ball, one outside. How practical is this? can it supply the necessary voltage and current to charge either a pair of NiMH batteries or a Li-ion cell? vik

Topic by askvictor    |  last reply


Soldering tips and tricks for complicated metals

Whether you are just a hobby builder or do your own electronics projects, you know how to solder...Then one day you find yourself in the position that your solder just does not want to stick...My first moment of total defeat happened when I was a teenager.Was building some simple motor with instructions from a book but substituted what I could...Ended up with some stainless steel contacts and being unable to solder my wires to them...If you ever had problems like this then read on ;)What are easy to solder metals?Basically everything that does not form an oxide layer on the surface and is able to bind with tin, lead or silver.Copper is one of the easiest metals to solder on but every plumber certainly knows how important a clean and corrosion free surface is.Any coating or alloy that prevents oxidisation or provides a harder surface usually means with normal, electornics solder we might be lost.Nickel for example can be a true pain and same for chrome.So lets start with the hard metals first.Steel, nickel, stainless...If the part size does not already mean trouble to get it hot enough, then we face the problem of how to "wet" it with our solder.Normal steel is usually fine if you give it a fine sanding right before the soldering, however getting the heat onto the part is crucial.Even something simple like a 5mm thick steel rod can be a pain with a normal soldering iron.I good way to cheat is to preheat the part or area with a blow torach on a soft flame - not a hot, blue flame.Try to do this away from the area you need to solder as the temperature difference usually causes some initial condensation on the surface.Most steels that play a vital role don't like to be overheated as it can affect the hardness an other things, so be careful here.Rosin core solder works fine on steel and it also indicates when the temperature gets too hot by boiling and smoking badly.If you still struggle to wet the surface try to scratch it with your solder - if it does not melt the surface is not hot enough.Nickel coatings are usually very thin and a slight sanding quickly reveals the layer underneath.If the metal used is not copper already then a copper layer will be electroplated on before the nickel coating.Either way the key is to get through the nickel without going through the copper, for example if steel contacts were used for durability reasons.After that soldering is as easy as directly onto copper.Steinless steel however can be a true pain, same by the way if you need to preserve the nickel coating as best as possible and can sand it off.Without using chemistry the only way I found is to use a stainless steel tip in the soldering iron.But as the preperation of one requires chemicals anyway we might start with them first.The passivating layer of layer or stainless steel can of course be pre-treated by sanding.Especially very shiny surface benefit from it.After this I prefer to wet the surface with Phosphoric Acid - you can find it in the harware store as "Rust remover".It is a food grade acid used in many of your favourite fizzy drinks, so skin contact is not a big deal - just wash it off.The phosphoric acid is not strong enough to break the oxide layer but it keeps air away.And once you start scratching the hot metal with your stainless steel soldering tip it will prevent a new oxide layer from forming.This method however requires a low temperature solder and quick work as the acid boils off quickly.In the plumbing section of your hardware store your find various fluxes for soldering.Look for something containing both Ammonium Chloride and Tink Chloride.Around here a common brand name is Bakers Fluid.Usually if it has a red danger label on it you will find the above ingredients on the lable somewhere.Be careful with it as it is very corrosive and harmful to your health!Good thing is that all remains can be washed off with just running water.What does it do though?Unlike the phosphoric acid, the chlrodies directly attack the metal.Especially once getting hot, so if in doubt wear proper protection as advised on the label!The oxide layer is not only being eaten away, there is also an ion exchange happening, so a product with more than 30% of zink chloride is prefered here.The zink binds with the stainless steel or nickel and provides an easier way to bond for the solder.Key is to work quickly and with precision!Flux paste is good for brazing but not so good for soldering.The flux liquid, unlike the paste will start to boil right when the metal get to soldering temperatures.That is if you use standard lead based solder, most lead free types should be ready a bit sooner.Start to scratch the metal with the solder and use a soft flame from the other side or close to the soldering area - do not apply the flame directly onto the flux covered area.Why? Well, the flux isolates the metal from the heat of the flame and it will boil off way before the metal gets hot enough ;)On smaller parts and when using the soldering iron create a small bubble of solder and keep scratching the surface while it heats up.In case the flux dries off apply a bit more before this happens!Once the solder starts to wet the metal a tiny bit it is usually very easy to spread it out to the desired size and shape.With the heat applied from the underside the solder will always flow to the area of most heat!Once done it is best to let the part cool down then to give it a good wash under running water to remove all remains of the flux.Failing to to do so will result in quick and ongoing corrosion, so do it properly...Aluminium, the bad metal...I encountered it first when I could not welding or brazing on a quite small part.Plus, of course, the problem of having to add a copper wire as well.Then again when I had to solder some aluminium wire.Acid won't work, chlorides only make it worse, so don't bother with either for aluminium.Standard rosin core solder also fails.But there is a suprisingly simple solution to the oxide problem on aluminium.Mechanical work...There are quite few videos out there showing how someone solders onto some aluminium foil.It is so simple because the foil is thin - use it to test your new skills.A thing though that is often done wrong is the surface preperation.It usually starts with a fine sanding - to remove the oxide layer.....The some oil is applied and soldering starts under the oil cover.And if pay attention then it is often a painful process of scratching with the soldering iron while trying to make the solder bubble wet the aluminium.That's why foil is so simple here....What happened in those videos?Quite simple: Aluminium oxidises right away while you sand it.Even if you are quick with the oil it already happened.So why not do the sanding after the oil was applied?A fibreglass pen or a stainless steel wire brush (usused on other things!) work quite well here.The oil prevents the air from attacking the aluminum.If in doubt use some clay and form a little dam around the soldering area to prevent the oil from running off.Petroleum jelly, vaseline and all other identical things work fine here same for clean engine oil.But you have to use rosin free solder, no flux core, just plain solder.If you don't have it simply melt some normal rosin core solder to a nice drop and clean the rosin off ;)Since there is no real oxide layer with this way of pre-treating the soldering and wetting happens right once the aluminium get hot enough to melt the solder.You might find it sticking nice right away but don't be fooled!You need to heat the aluminium until you actually see the solder forming a nice puddle.With careful sanding you create very clean boundaries.Other soldering tricks...Getting cholired based flux for a single job might be overkill.If you happen to have one of these tip cleaning stones for your soldering iron then you have what you need ;)Simply scrape some of it off and dissolve it is a tiny amount of water.Will only be ammonium chloride and requires more scratching on stainless steel but works...Preparing a stainless steel soldering tip sunds as easy as finding a suitable piece of wire and grindinga tip onto it.If you every changed the tip on a soldering iron them you know there is two types.The simple one for the cheaper irons uses a set screw or similar to hold the tip.The better ones are hold in place by a collar or other type of screw fitting.And well, those have a thicker part in their body.If you need to solder stainless steel more than once or twice it makes sense to buy a cheap but powerful soldering iron and to make sure it uses a straight piece of metal with no thicker parts to hold it in place.If you can't find some stainless steel wire or round bar of suitable thickness you can go slightly below or much thinner if you require a thin tip.Just make a copper or aluminium collar for the tip to hold it in place, like a sleeve to go around.Grind the tip to your desired shape before fitting it in....You won't need a mirror finnish and it can be helpful if the the surface is quite rough.After all, you want to scratch around on stainless steel with it and you can't harm it this way.To get a nice and clean cover of solder onto the tip you need the mentioned flux from above.Use a small cup and fill some of the flux in it so you can dip the tip of the soldering iron into it.If there is no temperature control start with a cold iron and the tip sanded off a last time right before dipping it into the flux.Use some clamps or whatever you feel like to help keeping the tip in place.If you get flux onto bits you don't want to cover with solder then wash off and try again.Turn the iron on observe the tip.As soon as you see tiny bubble forming take it out and quickly start rubbing your solder onto the tip.It helps to have a thick enough solder so you can apply some pressure here.And of course the solder should be nice and shiny and not covered by oxides...Special cases like titanium or othe metals that usually fail to bond with solder....Let's face it: whenever soldering is not feasable we are happy to revert back to crimping or screwing.Nothing wrong with it either and often the better option when it comes to being able to do a quick repair at a later stage.Most of thes special metals, including your favourite heating wire can still be solder using the right surface prep and flux but it really should be avoided if you can.And real bond like you get when soldering copper would only be on a surface level and mechanical strenght questionable.On a professional level ultrasonic soldering is used to make the impossible possible.The cavitation effect breaks through the surface oxides or passivating layers and the solder just wets the surface like it would be copper.On a hobby level things look different though.Unless you decide to build your own solar panels from scratch the investment into some low end ultrasonic soldering machine already set you back a few grand....There is a way to cheat on the cheap though if you are into experimenting and building things....More on that in my other topic about making an ultrasonic soldering tank. ;)

Topic by Downunder35m  


Scrounging Electronic Components

Old PCBs (printed circuit boards) used to be a great source for electronic parts. Especially if you need a power transistor, MOSFET, voltage regulator, big capacitor, or reed relay which is not available locally. It just does not pay to mail order small numbers of parts, so having a grab bag assortment at home is handy. But I have noticed that the some higher-quality PCBs just loaded with cool parts can be hard to scrounge from: 1. They are double-sided, or even multi-layered, with copper plating right through the holes (vias) so it is like pulling teeth, only harder. 2. They use no-lead (RoHS) solder which needs high temperatures to melt 3. They use surface-mount components and good luck removing and using those. I use 15 watt, 40 watt, soldering irons, solder sucker, solder braid, flux, and a soldering gun. And for some items, a small windproof butane "jet engine" lighter as a mini torch to remove multi-pin items. Just heat-sink the legs and bang the hot PCB down to remove lots of solder at once. Of course I use gloves, safety goggles, ventilation, and proper recycling. But the main issue is that it is getting harder to scrounge parts to build up a pile of useful stuff.  What resources do you use?

Topic by iectyx3c    |  last reply


Making a proper fire brick or refractory liner

If you are cheap like me then paying an arm and a leg for commercial grade refractory mixes or ready made bricks is no option.And how wants to make their design only to find there is no matching bricks for it...There is lots of totorials online and here on Instructables that deal with making heat resistent bricks and similar.And this is all well and good for normal melting applications or your pizza oven, not so much if you really need intense heat.I found that commercail mixes tend to be either really brittle once heated up or that they will glace up and even melt.So why not make my own mix...Ingredients:Fine sandCrushed PerliteVermiculiteSodium SilicateThe first three you find in basically every home depot or garden center.The last can be made from crystal cat litter and sodium hydroxide.Use proper PPE please!For a refractory mix I use:100ml of clean water.60g of crystal cat litter.About 35-40g of Sodium Hydroxide.This will provide a very silica rich solution.Use a high jar or similar and fill the water in.If you have use a magnetic stirrer, otherwise be prepared for manual labour.Add some cat litter but not so much that stirring becomes a problem.It will fizz around a bit and when it stops slowly add some sodium hydroxide.The mix will heat up and the cat litter starts to dissolve, once it is gone add some more.If it becomes hard to dissolve them add a bit more sodium hydroide but avoid letting it get too hot and so it boils!!A bit of steam is fine though.Towards the end you should have a quite hot mix with all cat litter inside and a bit of sodium hydroxide left.See what dissolves and only add as much as you really need.40g is enough, if it won't dissolve the cat litter then keep stirring every now and then and add some external heat, like placing it in a water bath on your stove.Once all is dissolved the mix is ready and should keep the jar closed to prevent it turning it a rock hard cement...Make sure your dry ingredients are well mixed and relatively fine in particle size.DO A TEST WITH JUST WATER!Take a defined amount of your mix, like 100g and see how LITTLE water in ml is required to turn in into a plyable mass like green sand.Note down this relation to get the right mix with the waterglass.To keep the mix workable you want to add the same amount of clean water to the amount of waterglass you calculated.If it is quite cold day you can leave it undiluted but give it a test on how long it takes to set on the surface to get your working time.Make sure you really mix it all properly to enuse the waterglass wets the surface of all aggregates in the mix.Press into your prefered form, remove form and let air dry, preferably on some wooden sticks so they won't accidentally fuse with the surface you have put them on.Once you have enough to fill your kitchen oven put them in at a heat of about 80-90°C for 3 to 4 hours.Open the door every now and then to let the moisture escape.After that they can be fired up to become fully fire resistent.Do this slowly as there might still moisture be trapped inside that needs to steam off, not boil off as it might crack the bricks.Once they got a good glacing from being used they might fuse together but should not constantly crack and melt like some commercial products - plus it come dirt cheap in comparison.

Topic by Downunder35m  


Tips and tricks for UV curing glue, resin and coatings

Only a few years ago your only option to repair certain plastics, glass or even a broken crystal was epoxy based resin or the good old superglue.You might have already tried one of the 5-seconds-repair pens or tried your own UV curing nail polish art at home.For the later you might be lucky as the resins used here are optimised for the purpose and lights you get with them.Sadly even the best nail polish is no substitude for a glue as the material properties need to be different.One of the most common complaints when it comes to using some UV glue, like Kafuter or similar is that it never comes with instructions.Sould be straight forward but it is not free of problems.For example almost all commercail UV curing glues that you can buy require quite stirct procedures and for the light the right wavelenth(s).Resins and coatings can be even more painful here as they might also require you to stick to the correct temperature.Let's start with one thing you might have encountered already...The glue is definately cured and rock hard but the surface tacky and smeary.Quite annoying if you want to fix a piece of jewellery and can't prevent it from collecting dirt and dust...The next thing you might have encountered is that despite having transparent materials it seems to be impossible to cure the clue.Both problems come down to wavelenght and exposure.UV curing glue is prevented from curing in the presence of oxygen - a factor utilised for example in resin based 3D printers.Uncovered glue is exposed to the oxygen in the air and won't cure easy.The glue or resin below this layer however with fully cure with ease in the absence of oxygen.For the second problem consider that not all materials that you can see through will let UVC light pass through ;)Bonding strenght is another complaint I hear a lot...Be aware that certain things just are no good for UV curing glues or resins.Take the molds you get for that purpose: on the material the glue won't bond!Teflon is another prime candidate here.But in a lot of cases it comes down to surface preparation.Don't be afriad to sand the surface!Not only will the surface area increase but the scratch marks will be invisible once filled anyways.Use sandpaper on your fingernails, then go over with clear nail polish -mirror finish ;)With curing often a problem consider to fully cover the glue.A bit of clear sticky tape, food wrapping foil....If that is not an option then eliminate the oxygen.You can use a container filled with inert (for the glue) gas like CO2 or just place a burning candle in it until it goes out....Either way the amount of oxygen should then be low enough to cure the surface of your glue.Not always is any of the above an option.Then you can still try more power and a lover wavelength.Mercury based lamps for example provide a very broad and powerful light that in most cases will cure within seconds.For a proper surface cure you need a wavelength of 265nm or lower.LED's offering this exist but at prices well out of range for the hobby user.A mercury lamp under high pressure is nothing for short term use and the limited lifespan does not always justify the costs of buying them.Like with most things in life certain inventions can have a dual purpose.Quality germicidal lamp systems for examples often state to go as low or even lower than 265nm.And they come at a fraction of the cost you have with a broadband mercury lamp.Even cheaper is the fre weather forecast.If the sun is siad to be strong enough so you need protection than even the worst glue will fully cure in seconds outside in the sun - tackfree!Don't be fooled and protect yourself!!These tiny LED lamps for your glue stick, the curing thingies for your nailpolish and everything else using UV light comes with warnings.For very good reasons!It might be hidden in the fineprint but you can not really see UV light.The blueish-purple glow you see is on the high end of what comes out and by that in the visible range of your eye.Just because a LED only gives a faint glow you see does not mean the UV light wouldn blind you if you could see it!Even worse for fluoroscent lamps or open cruning systems like those for your nailpolish.Reflected UV light is still UV light and you can still NOT see it!Stories of people getting sunburnt from germicidal lamps in a butcher shop or other people going blind from checking money as their living have a true base...In most cases lamps used well past their lifespan or simply the wrong type of lamp but still: the damage came from UVC light...If you just love creating your own artwork or jewellery with UV curing resins and glues than protect yourself.Proper sunglasses with a stated UV protection for example or just black nitrile gloves for your hands...

Topic by Downunder35m  


Please help me understand this 12VDC - USB circuit. Answered

This ties into my earlier question about the large resistor (Thank you, Quercus austrina et al). I'm an electronics newbie working on hacking a boombox into an under-cabinet kitchen radio.  One of the things I want to do is provide USB power to charge my BlackBerry while I listen.  I want to repurpose this car power adapter to do that.  It has a cigarette lighter plug, two cig lighter jacks, and one USB port. I have attempted to draw a schematic of the circuit as I understand it.  This is my first schematic, so be gentle.  Sorry about the small size.  You may need to click on it and choose "Original Size" to see it more clearly. Here are my questions: 1) There's a surface-mount resistor (R2) between the big scary "sandstone" one and the LED.  The numbers on that resistor could be read as "102" or "201".  If I understand correctly, it's either 1000ohms or 200ohms.  That's a significant difference. Which is it likely to be? 2) Likewise, the ceramic disc capacitor (C2) appears to be labeled 104, but is very hard to read, since it's hidden behind the other two.  There may be a dot after 104.  Would it be .1µF, then? 3) Did I correctly decode the numbers on the group of four resistors that provide current to the USB data pins? 4) Here's the Big Question:  If I remove the 7805 and everything to the left of it, and hook in 5VDC from a computer power supply, will it function? Thank you for your consideration.

Question by yoyology    |  last reply


Tesla's earthquake machine - revisited!

Nothing is better to beat isolation boredom than a good science puzzle.It's been centuries since Nicola Tesla was claimed to be responsible for a minor earthquake caused by one of his inventions.We can be quite sure the actual earthquake was just a coincidence that happened duiring his experiment but still...Inventors and scientists alike have tried to figure out how his appearently small and simple device could have caused effects that can be felt by people.Now it is time to reveal a possible way how Tesla might have done it.Harmonic vibrations are what cause structural things to swing, a reason why soldiers will never cross a bridge with the steps in marching sync ;)The famous London bridge was a modern example on how seemingly randomly generated pushes by pedestrians create one syncronous motions by all of them.You can replicate the effect with a rooling board that has a bunch of metronomes placed on it.Set to the same pace they will start more or less out of sync no matter what you try.But after a few minutes the moving board brings them all in perfect harmony.The above examples and a modern vibration speaker made me think...Tesla used terms like "airspring" and "harmonic coupling" to describe how his machine worked.We know Tesla did not use written notes and that his understanding of science was a bit different.Magnetism wasn't new to him.My proposal for anyone to try is this approach of his earthquake machine:We use a T-shaped housing with a mounting plate at the bottom.Inside is a hollow tube construction.Either side of the T in the top is an electromagnetic coil.Polarities of the coils are identical.In the downgoing pipe we have one magnet mounted at the bottom and another, smaller one in the top - the middle of the horizontal part of he T.Between them is a cylindrical magnet.The upper and lower magnets are selected or machined to keep the moving magnet centered.Preferably in an equal way, meaning the weight of the moving magnet should be compensated for by the other two magnets.The tube shall be providing a tiny air gap around the magnet - enough for a free movement but small enough to provide some air resistance.We created the airspring ;)At least if the tube is properly sealed.Theory of operation:In a vibration speaker we use the weight of the magnet and housing to transfer soundwaves onto a surface.This is a forced coupling that relies on the weight and inertia of the speaker assembly.A sinewave fed into our linked electromagnets will cause the magnet in the tube to move up and down with the amplitude of the sine wave.Electronics side of things:Tesla was a genius, I am not, so I need to cheat a bit now.With the moving part solved we need a way to syncronise our coils to the movement we need.In the most basic form by a simple sinewave generator and audi amplifier - helps to create 4 or 8 Ohm coils ;)However, to make it work in harmony we need one or two hall sensors.The sensors have two functions.Firstly they help to provide the right amplitude for both polarites to get a really even movement from the magnets neutral position.Secondly they provide the feedback to find the harmonic frequency(ies).Like the push-levitating platforms we need a PID control for the coils.The reference comes from the hall sensors like in the platform.Calibration needs to be done on a rocksolid surface.The calibration ensures the magnet will always move in a perfect sinosodial motion - in sync with the coils.In normal operation the hall sensor(s) will monitor the difference between set value and reality.The difference is used to adjust the frequency in small steps.Operation requirements for the electronics:During a frequency sweep the required amount of energy required to get the set movement of the magnet changes.The closer the frequency gets to resonance the less energy is required to push or pull the magnet.Like your kid on the swing.You would try to push when the swing is at the lowest point, you wait until it is just about to change direction ;)The sweep can locate one or several resonating frequencies depending on the set frequency range.The one causing the lowest energy requirements is usually the best.With the resonance almost figured out the electronics now start a fine sweep near the found frequency.From then on the frequency is adjusted to track the point of lowest energy consumption through the PID control.Detailed explanation:With the surface the device is mounted onto starting to swing the magnet becomes weightless at resonance - every time it reaches the top or bottom end of the swing.This means we need to adjust the sinewave so the coils only provide a push right when the surface starts to move in the other direction again.We also need to make sure this push is short and ends when the surface swing together with the coil push moved the magnet to the bottom - the surface push shall keep it here in freefall so to say.In theroy short ramped pulses would be sufficient here.Limitations of the design:As we still have no clue how Tesla create friction free air springs and can only guess how he found and tracked the resonant frequency we face several problems.1. The possible amplitude or lenght of the vertical tube is limited by what the coils can provide in electromagnetic field strenght.The need to be able to pull the magnet from the lowest point as otherwise the frequency sweep is very difficult to accomplish.2. Weight and lenght of the magnet.Ideally you want the biggest cylindrical magnet you can find.Realistically you need one that has a weight the coils can handle properly.No use having a 2kg magnet if then you need coils the size of door holding magnets.So going a longer and thinner might be the way to go.I found a ratio of 1 to 5 suitable, 1 to 3 still works but causes a lot more sideways push on the magnet and through that actually more friction than a longer magnet.3.Ventilation...You will notice that at very low frequencies there might be a "delay" caused by the air pockets either side of the magnet.If you can't ge a suitable air gap between magnet and tube it is often better to have a snug and friction free fit and to add venting holes either end.If the above three points are addressed and matched properly it is literally like you pushing a swing - the limit is the energy you have to push.Good thing is that we don't need to support a circular motion ;)That means the device is mostly only limited in what is possible by the electronics and code.More severe and vital to consider is the last part:Placement limitations:Imagine you want to test the device on a vertically mounted beam with sturdy support either end.The first harmonic would cause the center of the beam to swing but also means the ideal placement of the device would be dead center.In the center the device can support the movement in an ideal way.Place it half the center distance to the mounts (1/4) and the push from the device is far less effective.Furthermore you risk adding sub harmonics thanks to the uneven pressure on the beam.If used as a subwoofer to make your wooden floor shake during the action scenes of your favourite movie you would of course aim for a more hidden placement that would require to find a harmonic frequency that causes the desired effect in the right area of the floor.As a "destructunal" device you would need to find the resonant center of the structure and the frequency where this structure is able to transmit and amplify the motion throughout everything that is structural.Makes it quite unlikely to work as an earthquake machine but still can cause some interesting effects.Ok, if all this relatively easy to accomplish with some cheap electronics and a 3D printer then what about reality and physics?Before you go overboard on the testing and coding try a simple surface or vibration speaker with a suitable amp.Don't use the suction type thingies that use batteries, go for the bare driver (speaker).The amp shall be able to produce and work at frequencies down to below 20Hz.Sounds impossible but I had good luck with dirt cheap 25W car amps that have a 3.5mm audio input on top of the stuff for the car stereo.Most phone with a real headphone output are capable to be misused as a frequency generator.Mount the speaker onto a suitable testing surface, preferably centered.If you happen to have one of these tables with a glass sheet as an insert you can cut a plastic or steel shet to fit in there and add some window sealing tape to act as a cushion.Start at about 10kHz and adjust the volume so you can still tolerate the noise.Move the frequency down and you will notice that at certain frequencies the volume seem to go up quite hard.These are resonant frquencies that cause harmonic waves to form on the sheet.The lower you go the bigger the "spacing" between these waves become.When you found the one that causes a single wave to form on the shet in a suitable direction you will get a rather violent movement of the sheet.It will be required to crank the volume up the lower you go with the frequency.At around 50Hz you should hear this a an annoyingly loud humm.What works with a speaker works even better with a dedicated device that can accomodate for a growing amplitude on a surface and only uses pulses at the right time to move the weight around that causes the push.That means we can only fully utilise our device in stuations where we can match the device capabilities with the structure or surface in question.It is not hard to destroy a pane of glass with a surface speaker and the right right frequency but much harder to make a complex structure vibrate as intended.A very rigid structure with measures to prevent the swinging of supporting structures, like a building, is unlikely to fall in sync with the device.Ever seen these rope or banner swingers in action?They can create amasing shapes by their harmonic movements.Imagine how the rope or banner would look like if there were lots of overlaying swings at different frequencies - that is what you wuld have to fight and eliminate.Fear chamber anyone? ;)Subsonic vibrations are quite easy to do with such a device.And some people say that certain low frequencies make us feel unwell, even haunted.If your house is made from plasterboard and wood then why not transform a wall or the floor into a subsonic speaker?Imagine your next Freddy Krüger night with friends....Crank the volume up every time it gets scary and your friends won't know why this fun movie suddely makes them feel so scared LOL

Topic by Downunder35m  


An alternative to expensive grinding stones

For some people buying a decent grinding or honing stone is a lifetime investment.Prices of over $500 for a single stone of a very fine grid are not uncommon.But what about the average Joe who just needs to sharpen a knife or tool every now and then?If slicing and dicing is not your living than investing in a set of diamond plates might be better than getting a set of stones.But there are limitations, firstly their size and then how long they last.The later is really important if not used correctly as even diamond toold can be ruined quickly.In some case these small sharpening tools are hard to handle.The bigger plates can still be a pain if they don't come with a proper mount.Well, and if you forget to clean them after use and put them in a dry place it will be quite hard to remove the rust.A nice alternative I found is sandpaper, specifically sandpaper on a glass plate.Good wet and dry sandpaper is available from almost gravel to a 10.000 grid, above that you might have to make a special order.In general the finer the grid the more you pay due to the ingredients.I use a glass plate from and old scanner as they are both heat proof and really strong, window glass is not recommended here.The glass is covered with strips of kapton tape for the ease of later cleaning.The tape is then evenly covered with a contact glue, preferably the spry king to get an even cover.Same for the sheet of sandpaper.I try to get the glue over the glass edge a bit and to have at least two sides of the sandpaper going over an edge.Just to have an area to work close to the edge without risking to lift the paper off.Once a sheet is too worn I place the plat in the oven for a few minutes so the glue softens and peel the sheet off.If too much glue remians on the tape I replace it before I put a new sheet on.Of course you need a bunch of plates although it works fine with two different sheets halfing a plate.The thing works best under slow running water, so use your tinker skills to come with a suitable frame and water supply ;)But even with just a spray bottle it is a cheap way to replace a costly stone, especially if you do require a bigger surface area.

Topic by Downunder35m    |  last reply


Heated print beds - are they overrated gimmicks?

For years now I use my old, trusty Mega Prusa with the bare basics in terms of hardware. But basically every new printer out there comes with heated print beds and most users "upgrade" to one to get better quality prints. So I started to to check the reprap forums and other websites to find out why a heated would be a "must have". Quite a simple task you might think, but not so for someone who prints every material on a cold bed with success... What are the official pro statements for a heated bed? 1. Better bed adhesion of course. 2. Less warping of parts. 3. Far less problems with layer seperation. 4. Better print results. And of course there are a few more but not worth listing them. Why do I think most of the four statements are actually unrelated to using a heated bed? Bed adhesion is a matter of print material and surface of the bed / bed preperation, like tape, glue and such. If you filament peels off a cold bed with no adhesion at all it simply means the surface is either unclean or unsuited for the print material. Warping of parts happens because the material shrinks when it cools down, a heated bed is only able to keep a certain height of the print warm. Higher prints won't have any benefit in terms of better layer adhesion with a heated bed. Same goes for seperating layers. Unlike the common believe a heated bed does not fix this problem - it only masks it! Layers seperate because there is not enough bonging between them. This can be due to insuffient extrusion width, too high print layers, wrong print temperature and of course wrong z-axis stepping and wrong extrusion multiplicator. And how good a print comes out of your printer depends on a good calibration and proper print settings - again a heated bed only masks problems ;) Ok, so heated beds are nonsense, right? Well, wrong again ;) They take a lot of worry out of the daily print life to start with. Especially prints with big foot print will benefit, although PLA should never be a problem on a cold bed. If you print long parts in ABS or even Nylon you can have a hard time forcing the plastic to stay on the bed all around the print. A heated bed, with the right settings of course, can make sure your print keeps the shape until it is high enough so the bottom part won't be affected by shrinking anymore. My opinion on how to get the best results... Manage to print on a cold bed first! Smaller parts don't need a heated bed anyway, so use them to improve on your skills of finding the perfect bed material / coating! You will find that once you have really optimised your printer and settings most parts won't need a heated bed anymore. Once you are really happy with the result of smaller prints on a cold bed try something bigger and pay close attention to any problems on the way. For example a big print might start out perfectly but after about 5-10mm of print height you see the part starts to warp and slowly peels of the print bed - especially long parts or thin areas are affected. The infill also affects how a parts reacts during the cooling, so try the same problem print with solid infill as well as only 15% infill to compare - you can stop the print once the problem is identified, don't waste filament. Now comes the magic of the heated bed... You want the temp as low as possible but still high enough to prevent the warping! Why go low if high would help more?? Simply said: If the bed is too hot the part stays soft for a long time, which can badly affect layer bonding and shape. Imagine you squish the plastic on an already "hard" layer - the plastic is pressed flat to be within the set specs. Now if the the layer is still too hot and soft the plastic will push the lower layer in - which of course will expand outwards. So the layer can actually end up to be lower than it should be - layer will still peel ;) Start with around 50° C for ABS and turn the heat down gradually every 10 layers or 25 if you print really thin layers. If the part still prefers to warp go 10 degrees higher. But again: If the stuff would not stick properly on a cold bed work on that first! How do I print on a cold bed and claim it works fine? To be honest, with a lot of time spent on trying, calibrating and finding the right "magic" to put on the glass to make things stick. Nylon, if the part is big, can still be a frustrating task unless cardboard or Bakelite is used but I still prefer the glass bed. I no longer bother with tapes as it can be costly and I hate changing the entire setup just because I use a different material ;) As said, the main key is a proper calibration of hard- and software! If your prints look messy and you spend as much time cleaning your parts as printing them you know what I mean ;) At the moment my "bed magic" is a clear craft glue with methanol as a solvent, mine is from Aldi but similar products can be found in every craft store. The bed is sanded with 600 grid diamond blocks to be as flat as possible and to provide a bigger surface area for the glue. When mostly printing Nylon is first clean the bed with alcohol and put a layer of plastic primer on it before re-applying the glue. With the right temp settings this glue surface can be reused several times with increasing bond to the part. Once the glue start peeling off the bed it cut the area clean and apply another coat just in the spot. A single bottle of craft glue, diluted down by 20%, lasted now about 3 rolls of filament - not too bad for a 2$ investment LOL Seriously though, squeeky clean your glass bed using alcohol and / or acetone and play with different types of craft glue. You want the stuff that is clear and uses either methanol or ethanol as the solvent, don't bother with water based glues! If the glue sticks well to your part but peels off the bed easily try a layer of plastic primer on the bed first - do this outside! However, if your printer is only capable of using PLA anyway you might not want to bother at all and stick to tape ;)

Topic by Downunder35m  


expanded graphite heat-sink? Answered

Okay , I've searched and searched and cannot find what I'm looking for. Maybe the other diy'ers can help me. 1.What I'm looking for is a heat-sink made of expanded graphite or (carbon, graphite (∥) as it might be known as well) that is actually in the shape of a traditional aluminum heat-sink with the fins and NOT in the shape of thin film as it is very commonly available. I don't even know if it exists or is manufactured by any company. I've tried contacting some companies about it but they have yet to get back to me. The reason I want this is for the tremendous increase in heat conductivity as in this chart shown on this webpage http://physics.info/conduction/ . The application I am trying to use it for needs a raised, elongated surface area to displace heat semi-uniformly, hence why I need fins like a traditional heat-sink instead of the commonly available film expanded graphite online. 2. If it does exist or is able to be manufactured, would it be a ridiculously priced part or would it be a reasonable priced part? (Just doing small scale tests for now so it would be the size of a FET finned sink). 3. From what I've read it seems possible by maybe layering the films into a stacked lattice, keeping heat transfer perpendicular to the lattice, but what are your thoughts all? (I question bonding the layers myself but I don't know if you could hard press the layers together without a bonding agent since any bonding agent being used I believe would reduce the thermal conductivity quite a bit, but I'm not incredibly familiar with expanded graphite). Any and all help would be appreciated from this wonderful community Best regards, Velesh

Question by velesh    |  last reply


WHAT GIVES WHERES MY FLOPPY THREAD?!?

Sorry folks looks like the server screwed up my posting and i'll have to post my idea for home brewed 5.25in floppies all over again (the post eventually appeared several hours later so i deleted it) ok so where to start (*light bulb appears over head*) i got it if you have a 5.25in floppy get it out and look at it you'll notice that its pretty simple the first part you will notice is the plastic envelope enclosure thing which is just a single piece of folded plastic with some holes cut in it, just below the surface of the enclosure is a fabric or paper dust trap that keeps the disk debris free and finally comes the hard part the disk each disk has 3 components the iron oxide powder, the disk, and the binding glue stuff the holds the powder to the disk. now here is my crude theoretical unproven construction process 1. cut out the enclosure(i'm thinking a material like plastic card stock might work) (probable impossible by hand put it under a laser cutter or watter jet if you have one) 2.use 8 dabs of glue to glue the dust trap in place on the side of the enclosure that will come in contact with the disk 3.spray some adhesive onto the disk and bury it in iron oxide powder 4.remove the excess powder and spray it again with adhesive 5.carefully put the disk in the enclosure and fold the enclosure around it gluing the enclosure shut 6.stick it in your floppy drive and format it i'll have time to try this myself this summer until then feel free the criticize and question my sanity just PLEASE don't suggest buying disks from e-bay, thrift stores, flee markets, online, or any where else for that matter

Topic by clasic_traveller_diehard    |  last reply


Self-Flying Balloon

I have an idea to make a bunch of smallish balloons that have a LED sinside and small circuits that would control small heating elements to randomly change the density of the air inside the balloons, making them rise or fall. Just as a fun art project, making a bunch of them and letting them into a room for a party or something. A couple of issues I have: I'm having a hard time figuring out how to calculate the buoyancy, though that may have to come later once I decide on all the components. I don't want to use any lighter-than-air materials like Helium, just regular air heated up. I've been trying to find some small ceramic heaters, but I haven't had much luck. Ideally, something like this seems like it would work perfectly, but I need to find some that I can buy in quantities less than 20,000: http://cdsk.manufacturer.globalsources.com/si/6008801115398/pdtl/Heating-element/1070197186/Surface-Heating-Elements.htm Whatever I choose would also need to heat up and cool down pretty quickly so the rising/falling would have a stronger effect. I might be asking too much here. I'd need the whole circuit to be pretty small and lightweight. If I use an Arduino Uno, could I just transplant the ATmega328 into the balloon? If I used a small watch battery, would that even provide enough juice to operate an LED and a heating element? Anything bigger seems like it would be too heavy. As for the casing, I plan on whipping something up in Blender and printing it out in lightweight plastic. It would have to hold the circuitry and be airtight to keep the balloon sealed. Any thoughts or ideas would be greatly appreciated!

Topic by jemtan990    |  last reply


Extreme water cooling idea for computer chilling plus dust protection

I started to play around with some compressor cooling devices, otherwise known as fridges, freezers or airconditioners ;) As with everything it started with a lot of reading, some doing, more reading, well you get the point... Anyways, I am now running an old and portable split airconditioner on hydrocarbons instead of the already escaped R22 refrigerant. With all this experimenting I got reminded that my computer does not really like to do hard gaming work on these hot days. There are already a lot of infos out there on how to use water and/or heatpipes to cool your system. One thing that they all have in common is that you need a chiller to cool the water. Now, there are really tons of options here - from using an old bar fridge to hold the water up to big direct chillers that can be used 24/7 and cost a small fortune. Here in Victoria the weather might be more forgiving but up north the humidity will be your main enemy if you want to use any decent cooling system. Imagine 90% humitiy and the water condensing on pipes and coolers inside your computer... Some systems compensate here by using a temp of around 12°C at the lowest to minimise the risk of condensation. But I think we can do better for cheaper if we are willing to get dirty and salvage some scrap. If it also a great way to protect your computer in a dusty and hot workshop enviroment! Let me explain the thought: Considering the costs for a decent air cooled system over the expense for just a basic water cooling kit it might be worth spending the extra money otherwise. What makes a normal and not overclocked computer go too hot assuming it is clean and free from dust? Right - the outside temperature and how hard we actually use it. Normal systems are designed to work at a room temp between 18 and 24°C, we are often lucky to have it under 30 in the summer. Getting a CPU to just under 70° if the outside air is already over 30° is hard if not impossible. But what if the computer would be in one of these fancy server rooms that are kept at 16° throughout the year? Problem solved, just win the lottery to get your server room build. Step back a bit and think again ;) If we make an additional and well insulated enclosure to put the computer in we would only need to worry about making it pretty much air tight and keeping the inside always under 20°C. Now follow me to my imaginary shopping trip... First step is getting a decent sized cooler box - you can build your own of course I would go for these oversizes Esky chests. Next step is a visit to the local hard rubbish collection or scrap yard. We look for a bar fridge or water cooling tower that has a condenser that will fit on the side or back of our cooling box. Prefer something old running on R22 instead of R134a if you can. If the system already has one or two service ports for filling even better, otherwise see you get one from a different fridge or freezer. The fun starts back home where we now make a big mess. The cooling system needs to come apart and if not a tower the fridge around it has to go without damaging pipes or condensers. Perfect would be to have a working system and to keep it in this condition to avoid the illegal escape or refrigerant. It also make it easier than having to refill it again. On the other hand getting a system that is already professionally evacuated as most scrap yards now do anyway can make the modding easier - up to your skill set and options to have the system checked and filled. Once we have a naked cooling system we get the cold side into the cooler box. Either by creating a slot to slide it in or by feeding the hoses through holes if you plan to do your own thing in terms of testing and filling. The compressor part and "hot side" are mounted securely to the outside of the box. If you still have the thermostat working and connected you can now check your homebuild fridge. To get the computer inside you have several option, IMHO the easiest is use one big enough hole to get all cables to the outside. You want this hole to end up as airtight as possible, I found candle wax to be a good sealer if you place some painters tape on the box first. So far this was the easy part, the hard part is now to make sure the humidity inside the box stays as low as possible. When the compressor starts cooling the evaporator will go to very low temperatures, even if you set the thermostat to 10° the cold side will condese or even freeze the moisture in the air. Unlike with direct cooling option inside your computer we now have a "cold trap" outside the coputer that we use to our advantage! Easiest option here is to have a catchment under the cold side to collect the condensing water and to let it discharge through a small tube to the outside. Once the system was operating for a few days there should be no moisture left inside our box unless it is not properly sealed. At this point you could be tempted to just set the thermostat to the coldest possible - I advise against it! Imagine the inside of the box is below freezing - the capacitors won't like it to start with and since we now have all surface subcooled the moisture can condense everywhere not warm enough, including your mainboard. A temp of around 10°C should be more than enough for normal gaming and gives the compressor a chance to turn off every now and then so any ice can drop off and exit. If you like the idea use it and make a featured Instructable out of it, my time is too limited at the moment to get serious with this.

Topic by Downunder35m    |  last reply


Suggestions on making small (synthetic?) Go stones?

I'm looking into making myself a Go set. It's a very old Asian board game. There are a couple instructables on making a board itself, which is pretty straightforward. My problem is in the manufacture of the stones. Basically the stones are flattened out marbles in either black or white. The idea is a bi-convex round stone, usually between 5 and 9.2mm thick, around the size of an average thumbnail. Traditionally these are made out of agate, slate or something similar. My goal is to produce stones that are hard and rather heavy, to mimic the actual stone feel as much as possible. I'm going to need 361 stones for a set, and I want to make several sets (maybe half a dozen). My current best bet is to press clay stones with a mold, fire them without a glaze to avoid non-uniform surface due to contact points, then spray an acrylic coat for color and texture. I was hoping someone might have other suggestions. I was considering an epoxy/resin option that I could press in a mold, then dry into a hardened, dense synthetic stone. But I know very little about epoxies and my options in this. I've considered glass and machined metal, but I lack the facilities and skills. Stone is beautiful but I don't know where to start with detail grinding and mass production at the same time. Wood would be great, but I would have to find/make the world's smallest lathe and I think the man hours needed would be impractical due to the quantities. I'm limited in tools, resources and knowledge on the subjects at hand. I like the idea of making a mold with which I could press several stones at once. Cheap is good and the ability to do this without a kiln would be great. The clay seems my best option but my kiln access is limited, so firing upwards of a thousand stones would be difficult. So if you have experience with a synthetic that I could pour and harden, I would greatly appreciate it.

Topic by Legion    |  last reply


Producing Hydrogen to Function as a Lift Gas

The short version: I want to make hydrogen to fill model airship envelopes with, because screw helium. Help me make a cheap electrolysis device that can do this in under an hour (ideally), or come up with an even better system for production. My immediate problem is that I need a high-surface electrode that won't fail in a solution of sodium hydroxide.The long version:I've devoted a fair portion of my time to contemplating airships, primarily because they're awesome. Fell out of use with the rise of much faster aircraft, and the technology its fate sealed by the extraordinarily bad rep the Hindenburg gave it. It is still far from useless, however, in that lighter-than-air systems can lay claim to flight times measured in days, and sometimes months, thanks to the fact that they literally float in the air like a boat floats in water.Their day may have come and gone, but I still want to experiment with the technology and create some model airships of my own. Helium works okay as a lifting gas, but it remains expensive and isn't going to get any cheaper in the foreseeable future. It is for this reason that I am pursuing hydrogen, in the hope that I might be able to produce a cheap lifting gas for my projects. Unfortunately for my aspirations, hydrogen is surprisingly hard to get cheaply in decent quantities. Here's what I've figured out so far.For one, it is absurdly hard to find sites that don't veer into fringe science when talking about hydrogen. HHO production, Joe cells, power your car with water...it all keeps cropping up, and not only does none of this do what I want, the concepts are often poorly documented or riddled with problems. However, I have been able to glean some information from my research. First off, one of the easiest methods (and the one I'll be pursuing the most) of hydrogen production is through electrolysis. For those of you unfamiliar with the concept, you can basically take two electrodes, stick them in water, add some electrolyte (like regular table salt), and apply a decent voltage. You'll get hydrogen gas streaming out of the negative electrode and oxygen out of the positive electrode. Fancier systems use large tanks, platinum electrodes, and a strong acid or base as the electrolyte. To increase efficiency (yeah, it's not 100% efficient), there is ongoing experimentation with high-temperature electrolysis and ongoing research into an effective electrocatalyst.Now, when I did my research, I thought "Hey! This sounds easy! I'll just set the system up like explained, and away we go!" Unfortunately, those exclamation marks were unwarranted. My first attempt showed that production is mind-numbingly slow with small electrodes. Using salt had the wonderful side-effect of producing chlorine and sodium hydroxide, a.k.a. caustic soda. It's called that for a reason, and I'm lucky I didn't run it too long or I might have a chemical burn now. Now I know. Choosing a good electrode turns out to be a problem too, as most conductors oxidize quickly or dissolve in the solution (now I know why everybody uses platinum when possible). My aluminum foil electrodes in a sodium hydroxide solution? Yeah, that didn't work AT ALL. I had better luck with steel mesh, but I recently found that it seems to fail over time too. The only thing that isn't disappointing is the container and the collection apparatus: an inverted plastic bottle with some airtight hose running off it, connected to a gas valve. If the bottle is placed such that forming gas causes the internal water level to be lower than the external container water level, the gas will be pushed through the hose (no pumping necessary!). There was one good thing I discovered, however. Apparently there was a bit of soap or something left over in the container, and I ended up forming a bit of explosive foam as well. The hydrogen foam blows up like nothing else, and the oxygen foam makes a loud pop and sends (slightly) caustic foam all over the place. Totally useless but still somewhat cool, so long as you're not fool enough to do it in large quantities.So, as of right now, I've got a good container and collection system, but my electrodes suck and production rates are so low that it'd take me hours and hours to inflate a good-sized balloon anyway. I'll be using sodium hydroxide in the future as the electrolyte, skipping the chlorine production and observing the proper safety procedures. My top priority is finding a good electrode, my next is finding a good way to increase surface area, and my last is getting a higher voltage source than the 12V power supply I had lying around. Any ideas?

Topic by Cognoscan    |  last reply


Living salad, makerbot songs, and noodle!

My first day at Instructables, I found myself sitting on a chair fabricated by the guy next to me, listening to plans for a living salad which would grow through your plate, fertilized by worms below the surface and a stained glass window made of dried fruit, trying to focus on absorbing all the information Vanessa and Noah were dishing out. Just beyond loomed the amazing fabrication facilities, with rows of 3D printers, zillion-axis CNC machines, a stocked electronics room, every kind of adhesive you could dream of, and even a test kitchen! It was a makers dream, Pier 9 had the material and equipment resources to allow us to realize nearly any idea we could dream up, and dream we did. It was immediately clear that the one month my collaborator Kyle (https://www.instructables.com/member/kylemcdonald/) and I had planned to spend there was not enough. Sadly, it was all we had, so we got to work immediately on Noodle, a little robot with the I/O of a machine but the thoughts and feelings of a human. I could go on about the shop at Pier 9, but the thing that really made the experience for me was the people. Hosting 10-12 AIRs at a time, the studio was always full with people building crazy things. One day we'd experiment with Nick's instruments fashioned from rocks, sticks, and water jugs while sampling cocktails from Ben's machine and Rima's cricket ganache, the next day we'd admire Aaron's work on hoodies that zipped around your hands while being serenaded by Andreas' makerbot which seemed to be singing the future. We were all so excited and inspired it wasn't unusual to find half the group there all weekend long or into the wee hours of the night. I won't go so far as to say anyone slept the night there, but...  Not only did we get to hang out in the AIRea, but we also got to know all the others working at Pier 9. This was a building full of people willing to chat about anything from caustics to contests, lend you their skateboard so you could learn how, or demo their latest projects. Vanessa and Noah couldn't have been more supportive and helpful, and it was so inspiring to run into them in the shop on weekends hacking away on crazy things of their own. With so much going on, we sometimes had to work hard to tune it out and stay focused on our Noodle. Luckily, Kyle and I had worked together before and we were able to divide and conquer pretty productively. Kyle handled the fabrication aspects, spec'ing all the hardware and designing and lasercutting then 3D printing the physical enclosure for Noodle. I was heads down on the software trying to hook up our raspberry pi to Amazon Mechanical Turk, speakers, a display, a camera, and an interface. Thankfully, the long hack sessions were broken up by Vanessa coming by to peek at my computer over my shoulder and ask, "what's taking so long? how hard can it possibly be!" ;) I will end this post here and get to work finishing up our instructable before Vanessa hunts us down. If the specifics of our project are a bit cryptic still, all will be revealed with the instructable post (see attached pictures for more mystery). And to all of you considering applying to the AIR program, DO IT! If you are a motivated, curious person with energy and ideas you will have a blast. And the weather is ok, too. Thanks Vanessa, Noah and Instructables!

Topic by lmccart    |  last reply


Sharpening a concave blades like Kukri or similar

Every now and then you have someone approaching with the odd job.This time it was in the form of an old Kukri / Gurkha knife.Wasn't expecting this when I was asked a few days ago if I could sharpen some old knife so it can be used for camping.The knife had a few marks from hitting hard stuff or maybe the occasional nail.But the worst was that for as long as guy had that knife it was only "sharpened" using a belt sander.You know, these tiny machines advertised to give your (kitchen-) knife the perfect edge.We could now argue about the pros and cons of having a knife edge that is literally rounded.But once it was done so many times that the edge really looks rounded it becomes obvious why this method only works for thinner blades.Adding to the problem was the fact that the belt used was just over 1.5cm wide.Appereantly so it is easier to do the concave part of the blade.Lets just say lengthwise it looked like someone created a wave pattern LOLThere was nothing "straight" on this nice blade anymore.Now, if you look up how to properly sharpen thise Kukri knifes then you can find all sorts of really useful tips.One I really likes was to use some eraser and toglue sandpaper on it.Small and flexible enough to cause minimal damages to the curve towards the handle.Another nice one is to use half round diamond file, preferable of a finer grit in the 600 region.Should work fine - if you plan to invest an awful lot of money on such a file.I however like things quite often done the old fashioned way.The oldest trick in the book....Whether you are using chisels and work on wood, just love to keep your knifes sharp or go on long camping or hiking trips - sharp knifes and tools just become your thing.The main thing everyone tells you is a super flat surface for whatever is supposed to sharpen your blade.For the normal stuff that is fine and good and you only need to flatten out your stones every now and then.But what about these odd jobs?Imagine you would need to sharpen a long paper cutting blade on some machine.Might be over a meter long and it has to stay with a perfectly straight edge.Back in the day this task was not done with some very expensive stone of large size....Instead sandpaper of various grit was used on a flat steel surface.I actually prefer a small pane of glass and tape my sandpaper on it.Hard to find anything finer than 1000 or 2000 grit but you might be surprised how well this stuff polishes onces clogged up a bit.Its all about the right level of wetness...Anyways, for our Kukri in question I decided it is time to do the same but in a way that does not harm the blade, constantly cut into the eraser and still is solid and "flat".If you still work with a sickle then you already know where I am going here ;)I used a small diameter spray can as my surface to hold the sandpaper.Of course a piece of PVC pipe, round wood or similar would warok the same way....Sticky tape does not work well with sandpaper unless you use double sided stuff.But it is enough to wrap one round on the top and one on the bottom of the sandpaper on the can to hold in place.So much for the basics....If you know how to sharpen a knife then you also know that there is a prefered way of doing it.Depending on the blade and stone in question you literally try to cut a thin slice out of the stone with every stroke.Either stright or with a cutting motion.This works fine with sandpaper on a flat surface, not so much however on a round surface.Try it and you see how you cut off the sand from the paper and constantly ruin your edge.The only way to do it is to move with the edge.You start from the heel and stroke to the tip.The can is used likea sharpening rod and shall always stay at a 90° to the curve of the blade.Takes a bit of practice to find the right grip to hold the blade while moving and twisting the can but well worth it.The rounded surface only allows for a very thin area of the sandpaper to work on the edge.I started with 120 grit!!!It left a trail of destruction on the edge, at least in the rounded up section....Once I only had a very thin bit left on the edge from the old sharpening I switched to 240 grit until a flat edge formed.As the Kukri was a disaster this process still tok over 4 hours to complete.That blade was properly hardened too...The start of the finnishing was done by jump right to 600 grit paper.The first can was just slightly smaller in diameter than the concave bend in the blade - perfect to smooth out those nasty bumps.But with a burr forming now on the edge and minor mishap with angle of the can towards the curve of the blade would mean cutting into the can while sharpening the concave bit.Meant I used my emergency insect repellant can as I did not like the idea of hoping my pepper shaker would start leaking while sharpening ;)If you blade is not too damaged you can of course start right away with a smaller diameter.The process is the same as before.Move along the blade and keep the can at the 90° angle towards the curve.Once you feel a burr forming on the side turn over until you have a bur on the previous side again.Repeat until all the marks from the coarser grit are gone and the edge has a uniform shine.Switch to a finer grit and go as high as you can here.I had to stop at 1000 grit as my supply of 2000 and 4000 grit is out.Hints and tricks along the way....It really helps to do this sandpaper sharpening under running water.The paper won't clog up, you won't risk a losse grain making really deep marks...But on a bad blade this can take several hours and would do it with a small aquarium pump or so and some gloves.A fine but stiff brush and soapy water however do wonders to clean up used sandpaper!I prefer to use these re-used pieces before switching to a finer grit.In most cases they are already finer than the next grit and create a nice polish that makes the visual confirmation of your right angle and angle of attack easy.A kukri is a working blade!It is mot meant to make fish filet or shave you legs.It is somewhere between axe, big bowie knife and hatchet.That mean if you would dare to give a 8° angle either side of the edge you would have a pretty damn wide edge...Stick to the original in width but keep it nice and flat.It is good compromise between cutting sharpness and durability when for example chopping wood for your camp fire.DO NOT USE A BELT SANDER!!I said it before but have to repeat it again as there is people using a big belt sander with enough free space to add a set of wheel that creat the curve I got from my spray can.The guys in India that make these knife do this blind folded....It takes years of practise to get the steady hand required not to cut through the belt.The beginners start in reverse, meaning the belt runs towards the edge.These guys only to the basic forming of the edge with really coarse grit.Basically to remove the marks from the forging.After that the pro takes over the blades and he has the belt running towards the edge!If you are silly enough to try it at home be prepared to have the belt flying in your face very violently!!The reverse sanding can't be used to finnish a blade as you never get a proper sharpness and flatness right on the edge.So just stick to manual and take an hour or so longer but then be able to enjoy a cold drink when done.You need surprisingly little sandpaper in terms of clogging up and getting useless until you get to the finer grits.If you use a wooden dowel or similar then make it a bit longer and add strips about 6cm wide of sandpaper.This way you have all the grits you need in one place and can take them with you to keep your blade sharp ;)If you glue it onto the stick it is also quite easy to give it quick brush clean when done.The really tricky part starts from about 800 grit onwards.Every mishap on the concave part can mean damage to your paper or to your edge.When using stone most beginner think that using a lot of pressure is a good way to remove the material quickly.In reality however it is just a sure way to wobble the blade over the stone, especially if the blade is not fully straight.Sandpaper can be more aggressive than your stones as in our case you only work with a little area and every time you turn the can only a little bit you have a fresh piece of paper working instead of a slurry building up.This mean you really do't need much pressure at all.It is the repetition, not the pressure that gives you the edge if you don't mind the pun here. ;)For a real working knife stopping at 1000 grit once you do single strokes either side of the blade is sufficient.The tiny burr left will disappear quickly during use and the Chakmak can be used for a quick refurbishing after every longer use.Should mean you only need to get the sandpaper out once you edge actually started to get blunt again.The final stroke....There are those people that don't have a kukri to go camping...Some people like to collect them.Restoring an old kukri can be done like with any other knife.That is until you want a razo sharp edge that is also highly polished.This is quite possible with the original edge width on the kukri.But of course you can only go so far with sandpaper....Modern technolgy provides us with the solution in several options.Firstly we have the ceramic sharpening rods.Unless you can do with kitchen variety thickness you need to pay a lot of money.A short 8cm diameter rod can set you back over 100 bucks with ease.Especially if you want something that provides a mirror like finnish.And alternative that is often available relatively cheap is a ruby rod.They can often be found with slight damages that make them useless for laser applications.Even burnt out rods are still fine as long as they are not cracked.It is quite hard (literally) to give them a satin finnish but I found that good quality sandpaper is sometimes capable of doing it.I like one side smooth and the other half of the rod with a satin finnish to prepare the edge.On the budget there is quality wet and dry sandpaper as commonly used in paintshops.If used dry the finer grits tend to clog up on such a wide edge.Once you have a piece of 1000 or finer grit that is fully clogged up you can use to give the edge a final polish.With this you won't even need a leather strop anymore but as said it takes a lot of practise so you won't cut the paper in the concave area.The steel rod....If you happen to have a hardened steel rod, like from a motion rail, small drive shaft or a big drill then give it a try.When using a drill:Of course use the end of the drill, not the working part ;)Also make sure it really is motth as any burr from the chuck or such will cause deep scratches on your blade.If it starts to feel sticky after a few good stroke you know the drill method is working.If it continues to feel very smooth and you don't see any polishing effect at all if tried on a small area only then you blade is of really good quality.But then again you would have confirmed that already by the ongoing swearing during the endless hours trying to remove some material from the edge...A word of advise for the first time user of a kukri:Although a good kukri is hard to damage without hitting a stone or metal, you can make blunt very quickly.It is top heavy blade and requires a steady hand when working on other things than meat.Chopping into some wood and letting the blade slip can deform your edge.A little mishap can be fixed with chakmak but not if hit hardwood badly a couple of times.And tempting as might be to use it as a small hatchet or axe to split your kindling:Never hold a piece of wood and then hack into it from the top with your kukri!Not only can you miss the wood and hit your hand, the wood can also split far easier or in unexpected directions!If the kurki is sharp you then have a good chance to loose a finger or two!

Topic by Downunder35m