cold explosions

I know that by adding ammonium nitrate and water the compound gets cold. so my question is by using ammonium nitrate and other then water can I use to make extream pressure build up in a short time while still being cold. this question is not for any explosive device to cause harm to anyone or thing. just wondering if a cold explosive could be possiable. thank you

Topic by pokiesmokie   |  last reply

Cold fusion experiment

I have reproduced some experiments on Cold Fusion. not as a source of energy but how to blend a wire of iron from 2mm with less than 2 ampere or obtain gas fuel from the water and graphite (coh4) without using dozens of amps.Do you think may be is interesting to do an instructabels to the matter? are not my nventions!I have same video of this experiment on my youtube channe Almost all in Italian language.. but with a little explanation also in EnglishThe power supply that i use and the experiments can be dangerous.. I would not like someone to dye !

Topic by alessiof76   |  last reply

USB Cold Cathode?

Hi, I have been wondering about creating an ambient glow around the back of my iMac with a usb powered cold cathode light or led strip, could anyone help me with this? i would prefer a prefab solution that doesn't involve much soldering or modification of hardware but that stuff is not necessarily beyond my skill level. (and sorry if this is in the wrong place, its my first post :P )

Topic by awesomesquared   |  last reply

Nylon and substitutes on a cold bed

It's been some time and I made progress with Nylon. Aldi had some cheap craft glue with methanol as the solvent - this stuff works great for PLA, ABS AND Nylon. The common problem with nylon is that it has no real adhesion to anything, except cardboard and bakelite. Cardboard makes a clean up nightmare and bakelite is not always easy to find, especially not the right type. So I tried various glues, paints and primers but none was really suited for all printing needs. And the cleanup of the bed is imoprtant too as I did not want to spend hours scrubbing with acetone or similar nasty solvents. After the first great succes with the clear Aldi craft glue I checked the local 2$ shops and carft stores and found similar glueswith methanol as a solvent. Since not everyone is lucky enough to get these specials I will tell you what to look out for if you try clear craft glue: Don't buy anything that can be cleaned up with water - you want methanol or ethanol as the solvent in the glue! Do a test with the glue on something that usually does not bind well to cheap glue, like glass and blister packs. Let the glue dry and peel it off - it should be a clear film that is quite strong and barely streches when you pull it. It almost feels like hard paper. All good so far? Check if the nylon, pla or abs really sticks to it: Spread a very thin layer on a piece of cardboard and let dry. Add another, thicker layer and let dry again. Now hold it under your nozzle and extrude a bit of filament while moving the cardboard around. Let cool and check how good it sticks. In a perfect world the cool plastic should peel the papaer off with the glue. Time to prepare your print bed the same way and to start printing ;) Just use a very thin first layer and for the first layer much lower speeds than usual. I print nylon with 60mm/s and the first layer at just 25mm/s, any faster and the first layer does not look right. ABS and PLA are much more forgiving here.

Topic by Downunder35m 

Cold Weather Bike Wind Deflector

So I've taken an indirect pledge not to commute to school VIA car - by not buying a parking decal... Since school started, I've commuted, by bike, nearly 400 miles. But now it's starting to get cooler. I really don't like riding in cold weather. I typically wake up cold, get ready (still feeling cold) and getting on a bike when it's cold out is pretty uncomfortable.... So, for my next ugly bike abomination accessory.... My first wind deflector fairing prototype. I made a model in SketchUp (this was my "learn to use SketchUp" project), then from that make a development drawing (3D shape to 2D cutout) and cut that out of some scrap cardboard (I've got quite a bit that I rescued). Yes, there are flaws in this design - it's my first attempt :p As of now, I need to figure out how to mount this thing. I currently have some surplus 1/4" threaded rod at my disposal, I'm going to grab some and see where it takes me :p Comments?

Topic by trebuchet03   |  last reply

Does cold harm lithium batteries? Answered

I know that Nicad batteries can be damaged from being left in the car in sub freezing temperatures.  Is this also true of lithium batteries?  I'm in a northern climate where we experience below zero temperatures so I need to know if I have to keep bringing my lithium battery packs inside every time I park the car.

Question by etcmn   |  last reply

Can I etch a PCB in the winter...? Answered

I want to etch a PCB, but it is rather cold where I live. I had settled on the HCl/Peroxide mix, but I could use something else if need be. I wouldn't be worried about it, except I get the impression it's a good idea to carry out the reaction outside, where it is cold right now. If working outside in the cold is a no-go, is there any etchant that is "safe" (I understand that safety is relative, I mean along the lines not immediately gassing me) to use indoors with ventilation? If so, how much ventilation is needed? Are we talking an open window, or an industrial fume extractor? Also, I wasn't sure which category and channel would be the best, so if a mod or somebody sees this and has a better classification, go ahead and change it. Sorry for making this such a long question; I'd just like to be able to use my circuit board before I die ;). Thanks, dedgerton

Question by dedgerton   |  last reply

My front shocks

My front shocks are WAY too soft, i need help tightening them or making them harder, not including water. Thanks!

Topic by Yerboogieman   |  last reply

Toyota corolla DIY Cold Air Intake

So i have this idea, my car came stock with cold air intake, but i want to take it a little farther and do a Ram air intake (the air gets shoved in the car as you drive) what kind of tubing should i use? i have this plastic kind of dryer tubing and some pipe rings (adjustable) would that work? or should i use metal dryer tubing?

Topic by Yerboogieman   |  last reply

Keeping my equipment warm

Recently i went to take pictures in the middle of the night at Subfreezing temperatures and the front of my lens formed ice. so i need to keep the lens warm, there are many solutions but the one i thought would be fun to use is the use of a heating element. I found resistance heating wire, i would like to make an object that could fit around my lens and keep it warm. to prevent overheating i will use a microcontroller with temperature sensors to cut of the supply of electricity at a certain temperature. i just want to keep the lens at more than 5 degrees centigrade. I think my 12v lead acid battery will be enough for this kind of project. My question is how to do it, how much heating wire should i use? how much heat will it make? what wire should i use? Will it work? Any other ideas are welcome.

Topic by markosloizou   |  last reply

What is better for cutting steel a cold saw or band saw?

Im considering buying a cold saw or band saw but im just wondering what is better in terms of cutting quality,speed,noise and ease of use.

Question by legend4930   |  last reply

Can a glass, vacuum insulated container withstand temperatures in the -180 degree celsius range?

Is it possible to store liquid nitrogen and oxygen in a vacuum insulated container for a short period of time? i have a thermos that i though might work, but i want to be sure that im not going to have the thermos explode in my face when i try it. this is an old beefy thermos that can take at least 190 degrees celsius, but im not sure about the other direction.  

Topic by pedrogabman 

Car, Cold, Ice, Snow and Wipers and better defrosting question

So if you live in a state that gets snow and ice one area you can never seem to get all the ice off, or the area that seems to build up ice easily is your wipers. Now my idea is like the rear window, when you turn on the defroster it warms up wires inside of the window that melts and defrostes the snow/ice/frost etc. A. Any ideas how I would make something like that, where I could turn on a switch that would be hooked to the battery with a fuse in the line where I could some how coil the wire around or under the wiper to melt the ice on the blade and in the area where the wipers are "stored" when turned off. B. Any different ideas then the one above?C. Any ways to make a roll of plastic or something with the wires held in place?All thoughts, ideas, diagrams and explanations welcome =)

Topic by oddie1212   |  last reply

I have a 1985 ford f150 p/u 5.8lt 4brrl that runs real good cold but runs real bad warmed up?

It runs great cold but when it warms up it stalls  is hard restart it has a new carb  it has a new ign, . plugs wires cap and rotor. System dosent overheat

Question by dizzydog598r   |  last reply

Ammonium nitrate + mortar/pestle = death??

How risky would it be to crush crystalised ammonium nitrate (like in instant cold packs) in a ceramic mortar and pestle?

Topic by Dirtbiker460   |  last reply


I am new in the programming stuff and i have, un familiar error problem. I hope you guys cold help me. thank for all the answers!!

Topic by ברקו   |  last reply

Natural water resistant adhesive

Hi I'm looking for a natural, cheap water resistant adhesive that can be applied to plant matter Ideally soluble in hot water so it can be easily applied but insoluble in cold water. Any ideas?

Topic by Isjmarshall   |  last reply

What is the correct method to cast a medal using Sulphur?

I keep getting small pins when too hot and large air bubbles when too cold.... there is zero data on the net about casting with sulphur - please help!

Question by Doj   |  last reply

Frozen Soap Bubbles

Some clever person figured out that if you give soap bubbles enough time to fall to ground on a very cold night, by the time they reach it they will be frozen. Of course, pictures have ensued. Check them out as they are quite beautifulThanks Boing Boing!

Topic by randofo   |  last reply

Heat transfer through cement

I have a garage on top of garage because my land is on a hill. The lower garage is all concrete all the way around including the ceiling. The floor in the upper garage is the cement from the roof of the lower garage. I want to heat the upper garage, but I know the floor will always be really cold because it is cement and the lower garage is not heated. The lower garage does stay quite a bit warmer than outside temps.My question is this, If I heat the lower shop, will the floor in the upper garage and the upper garage that is insulated be warm as well? Or am I better off just heating the upper shop and having a cold floor? I spend a lot of time in the garage and would like it comfortable when I am in there. ThanksJed

Question by jedidieah   |  last reply

Follow the bouncing ball!

An article in PhysicsWorld reports on a novel technique for measuring the acceleration due to gravity. The researches used a cloud of ultra-cold atoms and bounced them off a series of upward laser pulses. By measuring the timing of the bounces they could measure g with better than 1 per mil precision.

Topic by kelseymh   |  last reply

A/C a room with Peltier units.? Answered

 Would building an array of peltier units in a windows frame work to cool down a room? This way hot air would stay outside and the inside "windows" would be cold. Either using heatsink and multiples computer fans to throw air in room or pumping water in pipes then on the units then to a big fan. Also, could this run on solar cells placed on the outside?

Question by gazoutg   |  last reply

can I have a small heater being powered by solar power and or wind?

I live in Scotland and I have a small greenhouse on my balcony, as the winter is coming and is already quite cold I was hoping it could be a way to have a small heater powered by solar power or wind power.  It doesn't need to put out high heat, just enough to bring the temperature so my chilli plants don't die.

Question by pjfsdias   |  last reply

Extra Attic Insulation. Can I add polystyrene panels over existing fibreglass batts?

I have access to 6in thick polystyrene panels which I would prefer to re-use rather than take to the garbage dump. Can I lay them over existing fibreglass batts to increase the insulation in the attic ? The house is 4 yrs old so is up to code and is located in Ontario, Canada where the winters are cold. I'm worried about causing a moisture problem.

Question by Blakie2   |  last reply

Is it feasible to add a kick start to my sport bike? Answered

I have a 200cc dual sport that has dual electric and kick start which i love for when i'm having charge/ battery issues or it's just reluctant to start on cold days. My sport bike is a zx7r with electric starter exclusively. Is there a practical way to add a kick start to this bike or (as i'm guessing) would it be way more time/ trouble/ money than it's worth?

Question by garretttm   |  last reply

Home Made AC for building/Workshop

I was curious   what   if  i  put a 16 cubic ft. chest  freezer in  my  small work  building   and  filled  75 % fullof  water . once frozen i  could  install and  4 inch pvc pipe in  one side  and  then another in the opposite  side.  On days i would  be working in my shop  for   a few  hours   if i pushed air  through  the   pipe  and  recieved  cold  air  out the other side.   Wonder how long  this would work  or would  it  work  at all? Andy

Question by andy1917   |  last reply

Room heat transfer?

Greetings all, I live in a solar powered house which is heated by a single log burning stove which is situated in the main living area. Is it possible for me to transfer heat to the colder rooms by simply putting ducting between the top sections of the adjoining walls (seeing that hot air travels to cold areas - in theory!) or will I have to use a fan? I am trying to use as little power as possible or ideally non at all. Has anyone got any experience of this or know of any suitable solutions? Many thanks in advance.

Question by peachvw   |  last reply

Need help making a snow machine- Can I make it snow at 50-60 degrees F???

Hi. I've been thinking about making a snow machine ever since I saw a report on that 10 year old kid who built a snow machine (Although if you're smart, you'd know his grandfather had built it)Anyway, I thought I could make one, since I have the two main ingredients: A Pressure Washer and an air compressor.I haven't researched that much yet, but this is my main lead for now.Anyway, I would like to ask you people a few questions:Although I just found some info on this, how exactly does snowmaking work? My main question is if I need cold water. I just read that because the water moves so fast, it loses some of it's heat, but I don't think that would make it cold enough to create snow. I suppose I should use cooled water, like from a refrigerator.Can I create snow at 50-60 degrees Farenheit? If I could, would it at least last about half an hour?I appreciate any and all info you can give on the subjet. 'Any and all

Topic by Keith-Kid   |  last reply

LED bike tires

We've seen all sorts of ways to light up your bike. Here on Instructables people have used LEDs, cold cathode lights, and even fire. Now a company called Cyglo is making new tires that light up with LEDs. They are powered by the spinning of the wheel. When the wheel isn't spinning you can see the individual LEDs. They blur together when the bike is moving for a persistence of vision effect. They're not on sale yet, but hopefully soon. And then there will be one more way to be brilliant while riding at night. Cyglo Night Bright Tyres turn on the magic of colored light

Topic by fungus amungus   |  last reply

stuck faucet handle help? Answered

It's a two handle kitchen faucet.  The last time I changed the washer on the HOT handle, I replaced both HOT and COLD plastic handles with metal ones.  I've removed the screw on top.  But can't budge the handle itself off the top of the valve unit.  Without the top screw, it should just slide up off the grooves on the valve unit.  I've tried prying.  I've tried rocking and tapping.  I've tried pouring hot water over the handle. Right now vinegar is sitting in the screw hole.  Usually this takes just a few minutes for the whole job. Any suggestions?.

Question by mole1   |  last reply

can I reverse the cycle on a refrigerator to warm the inside?

So I have just built (mostly) a workshop shed, and it's about time to move in work benches, tables, small appliances, etc.  I want to be able to move some temperature sensitive stuff out, too, and I don't want them to get too cold. I'm probably over thinking this and there's a simpler solution, but a refrigerator is already a well sealed, temperature controlled, shelf. If I could get a second hand or scratch and dent, could the condenser be put on the inside to make a "warm box" for winter?  

Question by harlyquin   |  last reply

How can I soften aluminum sheeting? Answered

Hi,    I have some aluminum sheeting that I bought in a roll from a hardware store. It is aluminum flashing, and although it has no rating, I assume it is about 26 gauge (.019") because if I remember right thats the standard. I cut the roll into 4x14" strips. Right now they behave like sheet metal, kind of springy and difficult to mould. What I need is more like thick aluminum foil, where it can be bent all around, multiple times without breaking and retain shape incredibly well. I've tried to cold work the aluminum by bending it and running it over an edge but its not very effective. Is it possible to easily anneal the aluminum in a conventional oven or using a propane blowtorch? I don't want to exert too much effort on each piece because they're going to have a short life before I hand them off and they get thrown away. In case you're wondering or need more details: I'm trying to make moldable aluminum splints, like the SAM splint. Pre-made SAM splints cost $4 each but this sheeting would work out to under $.11 each. In case you aren't familiar with them, SAM splints are essentially a plate of thick aluminum "foil," about 4"x36" wrapped in foam. The cool thing about them is that you can bend them very easily to any shape or body part, but when you mold them into a curve they have incredible strength to support an injury. 

Question by SeniorShizzle   |  last reply

Removing heatsink from air conditioner? Answered

I got an old (functional) AC lying around and before i get rid of it i tough i'll try to do something with it. I tough about removing the heatsinks from the rear coil and cooling it with another copper tube with water pool flowing in. This way i hope to achieve 2 things : incrase the eficiency of the AC by cooling it with another coil of cold water and heating my pool for free ( and hopefully with better and more constant results than the solar heater) Since im'not HVAC certified, i'll have to remove the heat sinks pieces without removing the refregirant tubings. Any tips on removing thoses?

Question by gazoutg   |  last reply

Slimy, disgusting, yet oddly touching (icky video!)

One of the strangest meal-times in the animal kingdom has been caught on film by a BBC crew.The team recorded footage of a female worm-like amphibian, called a caecilian (pronounced "Sicilian"), allowing her young to peel off and eat her skin.The video is a bit odd-putting if you don't like slimy, wormy things, but fascinating nonetheless.The videoThe storyFirst episode of Life in Cold Blood available for UK viewers with Internet Explorer, only available until 11-2-08iPlayer home (again, only available to UK residents)

Topic by Kiteman   |  last reply

How to make a homemade air door / curtain?

You might have seen them on your favorite super market. When you enter the store you get hit by an air current from above. They help prevent pests from coming inside the store and also keep the cold/warm air inside. The price for one of these units is ridiculous!! at least for home applications. They range from $200 to $3,000 depending on the size and air current speed. I can visualize a wood box with the aperture on it for the air to come out but the insides would be a bit hard to find under $200. Maybe one of those standing fans? I don't plan on doing the instructable but it would be nice if someone would ^_^.

Question by cybershadow1   |  last reply

How to make a home made air cooler?

I want to cool the air inside the cabin of a my boat but I don't have room to install even the smallest of air conditioners.  I would like to build something like a swamp cooler (Evaporative Cooler) but without the evaporative part.   I don't want to blow additional humidity around in the cabin.  I can use a pump to get a never ending supply of cold lake water.  I'm wondering if putting a fan in front of a radiator cooled with lake water will give me any sort of a reasonable deltaT on the air flowing through it?  Basically using a radiator in reverse.  Anyone have any thoughts on if this works? what kind of radiator to use?  and if I can get any reasonable temp drop on the air going through the radiator? 

Question by CrackKills   |  last reply

Burning Questions Indeed!!!!!

Do you have burning questions,about sooooo many things well it is time to find out their answers with alittle help from me...............But before you get the answers you have to do little effort,consider it a small quiz...believe we will have alot of fun with this!!!!!!!!! READY.............. 1.why do we feel sleepy after abig meal? 2.why does the sky look blue? 3.why do we feel cold after leaving the pool? 4.why does the sun look yellow? 5.why the eearth cools off in winter when there is global warming? you think the first landing on the moon was real,why? you think in 2045 people will use horses and donkeys to travel when oil finishes? PLZ REPLY SOOOOOOOOOOOOON !!! GOOD LUCK BALKEES

Topic by Balkees   |  last reply

Heat storage device for car cabin heater

I want to increase the heat storage capacity of the existing car heater so that I can run the heater (just the fan and a liquid pump) while the engine is off and so I can have a warm car as soon as I start on a cold day. The current heat storage is the coolant circulating in the engine. I want to increase the capacity of that. Instead of simply attaching a liquid reservoir to the heater circuit (to increase the coolant volume), I was considering using a picnic cooler (insulated) box with a coper tube coiled in it. The box would be filled with oil and paraffin. Paraffin melts ≈ 40° C  and I can take advantage of the latent heat of fusion when the paraffin changes phase. The oil is a medium to suspend the paraffin. I need a recommendation of an electric 12 volt pump to circulate the fluid. I request any other thoughts or criticisms.

Topic by nehmo   |  last reply

DIY dehumidifier design?

This is my first real foray into DIY so help me out here. My original design, which didn't work very well, was to fill some coiled-up tubing with the gel from that blue ice stuff you use to keep lunchboxes cool, then mount that  near the top of a bucket and keep a fan running over it to blow moist air onto the cold tubing and, theoretically, it would condense out. When I left in the morning it was definitely getting lots of condensation, and I even saw a bit dripping off into the bucket, but by the time I got back in the afternoon the whole thing was bone dry. Is there any way to make this freezer-gel-tubing idea work? I think part of the problem was that I used rubber tubing, not thinking about how it acts as an insulator, and I also suspect that keeping a fan on it did as much harm as good what with the whole evaporation thing, but I thought real dehumidifiers used fans too... Ideas?

Question by TheJenx   |  last reply

would this heater in my sheds future false ceiling be a good idea?

I've come up with an idea for a heater in my sheds future false ceiling. Its basically a wooden box with an unmodified hairdryer attached and four PC fans blowing the warm air down each of the 4 clothes dryer hoses to vents roughly at floor level. I've seen one ibble where the heating element and motor were removed and used but don't fancy that idea too much. The shed is brick with a reinforced concrete roof and gets extremly cold in winter. The false ceiling will be around 10 inches from the concrete to allow for the stone 9inch mantle above the window and door and gas pipe. The gas pipe is capped and don't want a boiller in a confined work space . Here is a plan of the heater (excuse the odd looking hairdryer) Forgot to mention the widhth and length are f 7ft x 6ft and the height is 7ft.

Question by cyberraxx   |  last reply

Can a 30 gal steel drum barrel stove inside a 55 gal drum heat chamber be integrated into existing HVAC?

I want to make a wood burning stove in my basement using a 30 gal steel drum for the burn chamber. Now the interesting part: The 30 gal drum will be inside a 55 gal drum, which will be the heat chamber. Will I be able to use this setup to partially or fully heat the 2000 sq ft upstairs? I was thinking of using a below grade through the wall stovepipe kit with integrated cold air return hooked to the 30 gal barrel, and then attaching the 55 gal heat chamber into the existing HVAC ducting. I would create the burn chamber with one of the many barrel stove kits like those available from US Stove. Bonus question: if this is possible, can I double the fun with a tandem setup (side-by-side or stacked) connecting the outer 55 gal heat chambers with a duct?

Question by sthain   |  last reply

Hamster's heating pad

The winter is on it way. I'm having a hamster, a winter white, but the last winter his caught cold and it cost very much for him to cure him. I don't want my hamster to be sicked any more, so I made a heating pad for him. I used this instructable and I found it is very well. I use a two - meter 26 - gauge wire, and it only result in a 0.15 ohm resistance. With an 1.5 v voltage, It work well and i need a 10a fuse to protect this circuits:) But last week it overheated and my hamster was burned, quite bad. I'm wondering if there is a solution to this. Would you mind giving me a circuit in which: - there is a thermistor to sense the temperature. - If the temperature is to high (30 celcius degrees ), it gives a relay some voltage and the relay breaks the heater circuits. - And it component should be popular, cause I'm a kid and don't have many time go round n' round to find them. Me and my hamster will very appreciate your kindness. Thanks all.

Topic by vietanisme   |  last reply

Repair on a Russian Belarus farm tractor?

Sirs, In 1990 we purchased a new Belarus tractor, made in Russian.  It came equipped with a large front-end loader and really for the most part it has been an economical, dependable tractor.  It has one small flaw, it doesn't like to start in cold weather, hard to believe they use these tractors in Russia.  Anyway my husband solved that problem by installing both a block heater which heats the water & an oil pan heater which of course heats the oil.  Only thing necessary is to either keep it plugged in all the time or plan ahead and plug it in the night before.  Now for my question, the seals on the arms which raise & lower the loader bucket and the ones that tilt the loader bucket are leaking hydraulic fluid.  Can anyone help us in changing the seals.  We ordered and received the necessary parts, but would like help with specific, very detailed step by step instructions to perform the repair.  It is our understanding the repair can be difficult if one is not careful in removing the end caps that hold the hydraulic cylinders.  Also the cylinder caps are external ones & the diameter is 40 mm.  Any and all assistance will be GREATLY appreciated.  Thanks so much, Debra Kay

Question by Debra kay   |  last reply

How do I keep my chicken's watering system from freezing? Answered

Hi!  I just found this site and can imagine I will be spending a lot of time here!  What brought me here today is a concern from last winter.  I raise chickens and developed a winter watering system that ALMOST works... It involves 80' of PVC piping that is circulated with an aquarium pump and was heated with a bucket heater.  The water is stored in a Coleman Cooler.  The birds access the water using 10 "Chicken Nipples" ( and here in lies the problem.  Even though the system flows in cold weather, the small amount of water in the nipple tends to freeze.  I imagine I could heat the system more, but I would rather have the heat directly on the nipples to keep them warm. I could use a light bulb on each but I would rather be more efficient.  I am hoping for a way to heat a bracket or coil around each one and have it turn on periodically as needed (maybe using a timer and a ThermoCube).  All the heat coils I find tend to produce too much heat and I am afraid of melting the plastic around each of the nipples.  I have spent countless hours at Home Depot, Radio Shack and electric supply stores trying to solve this.  Any help is greatly appreciated!   ---Regards Alexander

Question by amagnus   |  last reply

Fighting with Nylon ;)

As some might know I still use an old Gen1 Prusa but love the challenge of basically getting everything done with that oldie. One of my latest challenges of "always" printing on a cold bed includes Nylon. If you ever had troubles because you ABS or PLA filament got too moist you will already know what happens to your print... Nylon is even worse when it comes to moisture as you can't see or really feel it. I was thinking of making a complete Nylon guide as an Instructable but think I will start here to kick off some discussion first. So, we know the Nylon must be really dry for a god print as otherwise we get bubbles, bad adhesion and of course a foamy looking print. Well, not really... Let me explain: A perfectly smooth and shiny finnish is not always required, and with the right settings Nylon still forms strong bonds even with a foamy look. However, the dimensions of parts are affected as well - outside dimensions go bigger and hole diameters smaller. If that is no issue for your print then there is no real need to perfectly dry your filament ;) Speaking of drying: People use all sorts of methods to dry their filament, not just Nylon. One of the most common and most expensive seems to be the use of your oven for several hours to dry it. Another way involves food dyhydrators, bit less on the energy bill but still... Then we have the smart guys using the sun and silaca gel for the drying - good and great but so useless in cold and wet climates... My advise here: Take your time! I mean, sure you want to print right after the filament arrived in your letter box but a bit of preperation will save you filament and frustration. Usually filament comes in a sealed bag with a pack of silica gel and it should be dry and ready to use. But Nylon can become too moist within the time it takes to finnish a long print if you are in a wet climate. This means you start printing and all is good but the next day your new print looks ugly as for no real reason. Make use of these sealed storage containers. Put the filament in there with a good amount of indicating silica gel and only have a hole to feed the filament through - if in doubt use a bowden fitting and a short lenght of teflon tube to prevent friction. A piece of sticky tape over the hole when you don't use the filament and the filament is always ready to use. Reminds me to make an Ible for a suitable storage solution with spool holder... Anyway... When it finally comes to print Nylon you should know cardboard works best as a bed as Nylon sticks really well to it. I glue mine onto a layer of masking tape, this way it won't lift from the bed and I can still replace it very easy. But the most common mistake with Nylon is to print it too fast. The stuff really expands and shrinks a lot from filament to print and high speeds only too often cause the layers to seperate later on. Some people compensate with higher temperatures but I don't like the idea of fitting a filter system with activated carbon filters... Also keep in mind the intense shrinkage when setting the extrusion multiplier! If your ABS prints fine with 0.85 you can expect that the same sized Nylon prints fine somewhere in the range of 55-60! Now you also know why printing with thick layers is not such a great idea if you require all dimensions to fit. Although only outside accuracy can be done by cheating in the settings, getting outside, inside and extrusion widths settings accurate is almost rocket sience ;) Nylon is expensive or not available here in the diameter I require.... I had the same trouble and reverted to trimmer line and a modified, dedicated hotend instead. Why dedicated you wonder? Nylon can be real pain to clean as nothing dissolves and if you heat the parts hot enough to melt it you can not work easy with them. Having a decicated hotend means you won't run into the problem of burnt ABS or PLA clogging the nozzle ;) It also means you can match the hotend to the trimmer line you choice (more on that in a minute). For example, in some areas trimmer line of 2mm or 3.3mm diameter is the most popular and cheapest. Just drill out the hotend to cater for the new diameter, which I did after noticing the filament got stuck in the neck of the cold end ;) Trimmer line - does it matter which one? It does these days! Avoid everything that is not round or labeled with terms like "duracore", "dual core", "multi layer"  -basically all that indicates it is not just a single, solid stand of Nylon. Long lasting, special core line is great for your lawn trimmer but really bad for your hotend! PET, High temp nylon or even fibre re-inforced cores are in use, so in the best case you mix the nylon with overheating PET, in the worst you block your nozzle permanently. If it looks like it has a core or some sort of "mantle" around it, it means not usable.

Topic by Downunder35m   |  last reply

Is homeopathy a proven science?

Hi again people! This is yet another question to which i have to get definitive answers.  Is Homeopathy a proven science? Alternate medicines like homeopathy, Ayurveda are so common in my country, that most people tend to believe them blindly and are ready to take "medicines" from them for all kinds of problems, from Not-really-worth-bothering stuff like common cold, to moderate stuff like diabetes, and even extreme life threatening cases like cancer. To be honest, even i didn't bother looking into them much and few years back, i thought MAYBE it does work, after all so many people take it. But in my recent years, i have developed a condition known as psoriasis, so i had to start bothering as most people force me to take these medicines, as thus far, "Allopathy" does not have treatment to this condition. But alternative medicines claim they do. i was getting a little skeptical. When i started really questioning stuff, i didn't get quite satisfactory answers. Doing a little research on my own, i have seen videos from one of my favourite intellect, Prof.Richard Dawkins. He says that homeopathy is mostly bogus. When i question this to the people around me, specially the elders, they just throw it out of the window, and tell me that i am too young to understand stuff, and people who claim things know nothing about these kind of stuff. It is the same in case of Ayurveda. How far are these claims true? Is homeopathy(Alternative medicine in general) a bogus? If that is the case, then why is it so famous? Why is the community adopting it despite all this? Or have i misunderstood the concept? Do pardon me if my question was too long :)

Topic by charmquark   |  last reply

Can you check this design? Answered

On Aug 26 I posted an ask about a design of a new type of motor.  I received some good advices. Redesigned 02/10/12 The previous design had a major flaw, that went unnoticed at first but it became clear as I went into the construction of the prototype: the thermal barrier would be totally useless, because the steam produced in the boiler necessarily have to go through liquid water to make its way into the compression chamber. This would have two disabling consequences: 1) the vapor would cool quickly, 2) the water would heat up quickly, too. Since any heat engine operation is based on temperature differences, this failure is vital. The new design does not have that problem. The water falls directly into the hot boiler, a small amount at a time, with the piston in the upper dead point, or below (note that my drawing is reversed with respect to what would be a conventional combustion engine). The water is kept cold by being stored in a separate reservoir, attached to the motor body only by the inlet and outlet pipes. Water injection is performed by momentarily opening a valve at the appropriate time. Since the interior of the water reservoir accumulates pressure as the engine works, this pressure would be in principle the responsible to force the output water through the tap. If that's not enough, I could add a little manual compression pump to initially load the reservoir with compressed air. So once the Primus heaters worked, which were extremely useful for decades. The exact moment, quantity and duration of water injection should be adjustable during operation of the engine, to find the optimum point for these parameters. These mechanisms have not thought of yet, but they can not be too complicated. As regards the boiler, it is likely that one heated surface be insufficient to rapidly vaporize the water, since in these conditions it usually adopt a globular shape that greatly retards heat transfer (Leidenfrost effect, http://resnickscity.wordpress .com/2011/01/page/3 /,, I think that could be solved relatively easily by a double bottom to the boiler, in order to "force" the water into laminar contact with the hot surface. If this is insufficient, it would still be possible to inject the water by pressure between two heated surfaces. I have to also investigate the possibility of to make "super hydrophilic" the surface of the boiler. Regarding the compression chamber, this design makes it much longer, thus establishing a better differentiation between the bottom hot and top cold. But the main novelty is that the displacer stops acting on a small amount of water to turn acting, as in the Stirling engine, on the entire volume of the steam in the compression chamber. By forcing the steam to move towards the cold zone it produces its condensation, thereby changing the pressure by decompression, and so completing the cycle of the engine. The condensation water adheres to the cold walls of the chamber, then it slides down by gravity, and is intercepted midway by the retaining ring, which leads it back to the water reservoir through a single action valve, spring driven. I guess that to pass the water to the reservoir will be enough the vapor pressure that occurs in each cycle. The accompanying drawings are quite precarious, but only pretend to give a general idea of the design. Please ask me if you want more details ------------------------------------------------------------------- Nuevo diseño 02/10/12 El diseño anterior tenía una falla importante, que me pasó desapercibida al principio pero se hizo evidente a medida que avanzaba en la construcción del prototipo: la barrera térmica iba a resultar totalmente inútil, dado que el vapor producido dentro de la calderita tendría que atravesar forzosamente el agua líquida para abrirse camino hacia la cámara de compresión. Esto tendría dos consecuencias inhabilitantes: 1) el vapor se enfriaría rápidamente; 2) el agua se calentaría también rápidamente. Dado que el funcionamiento de cualquier máquina térmica se basa en las diferencias de temperatura, esta falla resultaba vital. El nuevo diseño no tiene ese problema. El agua cae directamente dentro de la caldera caliente, una pequeña cantidad por vez, estando el pistón en el punto muerto superior, o sea abajo (ojo, que mi dibujo está al revés respecto de lo que sería el de un motor a explosión convencional). El agua se mantiene fría, por estar guardada en un reservorio separado del motor, unido a él solo por los caños de entrada y salida. La inyección de agua se realiza mediante la apertura momentánea de un grifo en el momento oportuno. Dado que el interior del reservorio de agua acumula presión al funcionar el motor, esta presión sería en principio la encargada de impulsar la salida del agua a través del grifo. Si esto no fuera suficiente, habría que agregar una pequeña bomba manual de compresión para cargar inicialmente de aire comprimido el reservorio. Así funcionaban antiguamente los calentadores Primus, que fueron sumamente útiles durante décadas. El momento exacto, la cantidad y la duración de la inyección de agua deben ser regulables durante el funcionamiento del motor, para hallar el punto óptimo de esos parámetros. Esos mecanismos no lo he pensado todavía, pero no pueden ser demasiado complicados. Respecto de la caldera, es muy probable que una sola superficie recalentada sea insuficiente para vaporizar rápidamente el agua, dado que en esas condiciones esta suele adoptar una forma globular que retarda mucho la transferencia de calor (efecto Leidenfrost,,, Creo que eso podría solucionarse con relativa facilidad haciendo un doble fondo a la caldera, de manera de "obligar" al agua a establecer contacto laminar con la superficie caliente. Si esto fuera insuficiente, siempre quedaría la posibilidad de inyectar el agua a presión entre ambas superficies recalentadas. Tengo que investigar también la posibilidad de hacer "súper hidrófila" la superficie de la caldera. Respecto a la cámara de compresión, este diseño la hace mucho más larga, estableciendo así una mejor diferenciación entre la zona inferior, caliente, y la superior, fría. Pero la principal novedad es que el desplazador deja de actuar sobre una pequeña cantidad de agua para pasar a hacerlo, como en el motor de Stirling, sobre el volumen completo del vapor contenido en la cámara de compresión. Al obligar a este a desplazarse hacia la zona fría produce su condensación, cambiando así la presión por descompresión, y completando así el ciclo del motor. El agua de condensación se adhiere a las paredes frías de la cámara, resbala luego por gravedad hacia abajo, y es interceptada a mitad de camino por el anillo de retención, que la conduce nuevamente hacia el reservorio de agua a través de una válvula de simple acción, a resorte. Supongo que para hacer pasar el agua al reservorio será suficiente con la presión de vapor que se produce en cada ciclo. Los dibujos adjuntos son algo precarios, pero no pretenden más que dar una idea general del diseño. Por favor, pregúntenme si quieren más detalles.

Question by rimar2000   |  last reply