Minimum Venturi Diameter??

Hi, I'm trying to make a venturi in an application. I've run some simulations with success, but as soon as I simulate it with the right scale (4mm diameter inlet of pressure) the simulation doesn't appear to show any venturi effect and the vacuum doesn't work. Does the venturi effect have any minimum diameter to make it possilbe? If not, how can I generate vacuum using a 4mm inner diameter tube? Thanks, Yair.

Question by yairtzur   |  last reply

Anemometer and the diameter vs circumference

Various Instructables have been created for building a wind speed anemometer, and nearly all use a bicycle speedometer for the read out. My question is, regardless of the actual diameter, the sensor can be close to the outer rim, or close to the hub, because one revolution is going to be one revolution and register as such on the speedometer. So, setting the speedometer to whatever rim size you desire, the readout would be correct. If you set the tire size to 24", then each time the sensor is tripped, it will show the speed for that tire size.  The same with 27" or 28" tires. The reason I'm asking is because I'm putting together a 'gopher chaser' from Harbor Freight (on sale last weekend for $1.50) which measures 17 3/8". I have no desire to cut new blades from sheet metal.... Thanks for any input on the issue.

Topic by GrumpyOldGoat   |  last reply

Find the inner diameter of the pipe whose inner diameter is varing in the range 0.5cm to 8cm?

I need to measure the inner diameter of the pipe the range of the inner diameter is 0.5 cm to 8 cm . what should i use ? laser ? or I.R sensors or anything else that  you can suggest ?

Question by thakkarjinal99   |  last reply

In a threaded rod, are the threads counted in the diameter? Answered

E.g if you have a 3/16 inch threaded rod, will the diameter of the rod exceed the 3/16 inch, or is the rod 3/16 inch regardless of the threading?

Question by astroboy907   |  last reply

Measuring device wich read the dimensions of an object in 1 time?

I want catalog my collection of inkwells, including the dimensions of each object (length, width, height, diameter). The largest size is 50 cm. I wonder if there is a device that measures all the dimensions in one time, whether or not electronically. If not, do you have suggestions so I can make it myself? All ideas are welcome.

Question by Frederiko   |  last reply

Reduce steel tube diameter by 0.3mm Answered

I am trying to make a DIY CNC machine, using linear rails and the expert advice in the many awesome instructables out there on this topic.  I hit my first roadblock, and I need some help/advice please... The 16mm steel tubes I ordered for the sliding rails wouldn't fit in the 16mm linear slide bearings SCS16LUU that I ordered, they are ever so slightly too big. With a lot of force I could get the rail in the bearing, but it wouldn't slide without extreme force - certainly not the smooth sliding motion it's supposed to be! I've probably ruined the bearings by forcing it in, but I'm not worried about that so much right now (I have spare bearings). I broke out the digital callipers, and the rail diameter measured 16.3mm - that's .3mm more than expected, and more than can fit in the 16.0mm bearings. So now I need to reduce the steel rails by 0.3mm. I have only hand tools at my disposal, and no experience accurately reducing steel rod diameter. I guess another alternative is increasing the slide bearing diameter, but these are sealed bearing units and difficult to get at. Does anyone have any ideas ?  Would it be easier to order new steel? Please let me know any thoughts on this, I'm desperate here.  Thanks in advance,

Question by srah1   |  last reply

1/2" PVC inner diameter?

I was looking at all the excellent instructables about marshmallow guns, but I have a concern. I'm Canadian, and it seems to me that the inner diameters of 1/2" PVC pipe in the US is larger than 1/2" PVC in Canada. So, could someone in the know please straighten this out? Is there a difference or not? If so, what would be the appropriate substitute size? Thanks to all.

Topic by Spongeloaf   |  last reply

how to strip large diameter copper wire

If you have say 2 inch or better diameter copper wire to strip here is what I do. I have ben in the scrap arena for years. Buy a large handeled pair of shears that are only for copper. They will look much like a large pair of boltcutters. Cut your insulated wire into about two foot lenghts. Get a large pot, the bigger the better and heat with an out door propane burner full of water. Place the cut sticks of wire into the boiling water fro about five min. Get some insulated rubber gloves and a sharp razor knofe and you will find that the plastic insulation carves away like butter. This works on everykind of insulated wire I have come across. With lead wrapped insulated wire, get a plasma torch. It cutts easily and is so fast the plastic wire inside does not have time to catch on fire. Use plenty of ventilation to avoid breathing lead based fumes.

Topic by beserker   |  last reply

Is it correct that if an 8-inch diameter wheel was rotating at 1,000 RPM then the vehicle would be going 12 MPH? Answered

I'm making an electric mountain board and I am trying to find what gear ratios work to get the speed I want. I don't know if my math is right and I was just checking.

Question by bowmaster   |  last reply

What's the diameter of the NERF Longshot CS-6's barrel extension?

I'm currently using the existing Longshot barrel extension for my Recon, and I want a replacement for that to put one on my Longshot to make it look like a... well, a Longshot. If possible, could anyone recommend me a diameter that would fit snugly and yet still be able to be removed? I don't want it falling out while firing or holding, or not being removable.

Question by cld0000   |  last reply

What is the best way to affix a hose with a 1/4 " inside diameter to a pvc pipe with a 3 " inside diameter?

Kind of like what this guy has in his instructable video:$20-by-convert/ but a lot better.  For my application it has to be something that can be tightened down into place.  It has to seal.  Also instead of a mason jar I'm using a pvc pipe.

Question by mattbliese   |  last reply

Looking for a slew drive less than 7" in diameter?

Desperately looking for a slew drive less that's than 7" in diameter?  Preferably with a nema stepper mount.  Don't want a rotary stage or table, looking specifically for a slew drive. thanks.

Question by sensoryhouse   |  last reply

IDEAS... How to make a 4m diameter hallow sphere ??

Hello all this is my first post on Instructables so thanks for taking the time to read ! I am looking for ideas on how i could manufacture a perfect, hallow, fibreglass sphere measuring around 4 metres in diameter (BIG) :) I have experience with using fibreglass but I am running out of ideas for how to make a plug on this scale and get it to be perfectly spherical... It has to be made from Fibreglass so i am really asking for help on making the mould. ANY help or suggestions would be gratefully received no matter how wacky ....I am willing to try anything. If your idea works I will be more than happy to name the first of these epic spheres after you !! All the best  Ben

Topic by whitto2017   |  last reply

Where can I get a 3 foot diameter (drainage) pipe?

Where can I get a 3 foot diameter drainage pipe? I need one that will stay strong if you go down 10-20 feet in water. I would also like it to be cheap to (around $100 or less). I just cannot find anything anywhere.

Question by GhostAction   |  last reply

Where can I find a 1.5 inch diameter copper cable? Answered

I am creating a giant i duction heater, and I need 1.5 in diameter copper cables. Where can I find one to buy? Or do I have to make one? Or is there an entirley better way to make an induction heater?

Question by anul20   |  last reply

Need to purchase small diameter metal tubing with screw-on flush endcaps?

Hello, I am looking for a supplier that sells metal tubing, steel, very small inner diameter with threading inside and end-caps that screw on to make it flush and appear as a solid metal rod (rubber O-ring if needed to keep dry).  I am attempting to make paracord survival key fobs.  I want to fit various tiny survival gear inside the tube, closed on both ends then weave the stitching around the rod.  When needed the user can unravel the paracord for use with what's inside the tube.  It must be tubing because one of my ideas is to put thermite inside a tube, wrap some magnesium ribbon around the outside, then stitch the fob around that.  Other ideas include other types of survival gear but that one will be my fire starter fob.  :)   The rods would be about 2-3 inches in length, wall diameter thin but sturdy, inner diameter maybe 1/4 - 1/2 inches.  Thanks for any help.  Rounded end caps would work fine as well as they would give me more room to stuff things in, but I need access to the suppliers for both the threaded tubing and end caps.  :)

Topic by lmiller31   |  last reply

Secure Bamboo Poles (150mm diameter) to top of wall (replace coving)

Hi there I have 2 x 3m Bamboo split poles to secure to the top of wall as a border/replacement for coving.What would be the best way to secure to the wall? I cannot hammer into the wall due to a pipe running behind where the bamboo will go.Velcro? Silicone? Double-sided adhesive pads/strips?Don' want it falling down during a meeting LOL

Topic by GregoryD45   |  last reply

Where should I look for a cheap large-diameter telescope mirror?

I'm looking for an inexpensive telescope mirror to attempt some DIY Schlieren photography. I don't need a flawless one that you would put in a telescope and use in an observatory, I'm looking for the one that fell off the back of an astronomer's truck on the way up the mountain and got a scratch down one side and a nick in the silvering to make it worthless for astronomical observing. Any handy "old junk telescope parts" websites out there?Or better yet, does anyone reading this have a decrepit old mirror sitting in their garage waiting for me to buy it from them?

Question by CameronSS   |  last reply

what should I do with 20 1-inch diameter steel balls? Answered

My brother recently gave me 20 1 inch diameter steel balls that he was trying to use to cool down coffee without watering it down (in hindsight, aluminum has a much higher heat density, but that's beside the point). I've had them laying around for a while now, and apart from a big newton's cradle or maybe a huge marble machine, I can't think of anything to do with them. ideas?

Question by codongolev   |  last reply

Question: does anyone know if there is an aluminum pipe expander over 6" in diameter

I would like to find a portable aluminum pipe expander a half inch over 6" for repairing aluminum irrigation pipe or any other ideas about how to repair them. thanks ron fancher

Question by flagman12   |  last reply

What can the focal lenght of objective lens of 5 inches diameter be? Please help

What can the focal lenght of objective lens of 5 inches diameter be?

Question by    |  last reply

the clear tube 2" long by 1 1/2" inside diameter where to find?

The clear tube 2" long by 1 1/2" inside diameter i tried searching on tap plastics but cant find the correct one. its based on    below they wrote Optional stuff to add style the part where they wrote "1-clear tube 2" long by 1 1/2" inside diameter" i cant find.

Question by jlee28   |  last reply

where can I find 3 1/2" diameter friction drive wheels for a project?

Making a miniature pitching machine for paintballs

Question by PBIF   |  last reply

Where can I find a clear acrylic pipe about one foot in diameter?

I am planning on building a fish tank, so I need a clear pipe about a foot in diameter, between two and four feet long (but it can be cut, of course) I'm in the UK, can anyone give me an idea of where i'd get it?

Topic by chimpanzeeboy   |  last reply

Stopper thermowell for DS18B20 temp sensors?

Does anyone know of a thermowell stopper that would fit a DS18B20 temp sensor? The ones I've come across look to have an inner diameter of .25 inch, and the DS18B20 probe diameter says .24 inch. Are there any other thermwell stoppers out there with a wider inner diameter? I'd like to go with a thermowell stopper so I can use it on buckets and maybe carboys as well.

Question by DELETED_MakiY2   |  last reply

Is there some sort of rigid tubing with a 40 mm interior diameter to fit an airsoft grenade?

What material, size and thickness of tubing (pvc, abs, copper) would be necessary to fit a 40 mm airsoft grenade inside of. It would need to be either 40mm exactly or slightly larger, although I'm not sure how much larger it could be.

Question by travisttt   |  last reply

where can i get smallish but loud cheap speakersabout say 2cm in diameter? Answered

I need some small speakers for a portable speaker project, i no yes it does sound like every other portable speaker project but it is slightly different. So the speakers need to be smallish about 2 cm across but still quite loud, any easy places to get them from?

Question by mdog93   |  last reply

Can you identify this tool? I believe it is used on firearms.

This tool came in a box of firearm items, however we have been unable to identify what it is or what it would be used for. The overall length is 2 7/8 inches, largest diameter is 3/4 inch, smaller diameter is 7/16 inch, has a 3/16 slot on one end and two 1/8 inch pins in the larger end, pins are 1/2 inch apart. There are two holes cross drilled in the smaller diameter, they are each 3/16 diameter and are 15/16 inch apart. The metal is blued same as a firearm would be. There are no identification markings on this tool.

Question by JamesJ3   |  last reply

What are these(Allen wrench like thingies)? Answered

I found these in an old toolbox. They are hexagonal like an Allen wrench, but have a smaller diameter round protrusion on one end. They are all the same size in "diameter". That's a standard size Sharpie marker there for reference.

Question by jrh065   |  last reply

What diameter hole do I need to drill for a standard E26 lamp socket nipple? Answered

I live in the UK and am making a lamp for a friend in the US. They are going to fit the socket and wire but I need to drill a hole for the nipple to go through to seat the socket. What diameter hole should I drill to fit a standard E26 brass socket nipple? (I've added a picture to show the kind of socket I have in mind) Apologies if any of the terminology is off, it's all very different in the UK! Thanks for your Help!

Question by chuckstuff   |  last reply

Where can i find a British Standard Cycle Die (9.35mm diameter, 26TPI) in the UK

Im after a British Standard Cycle Die (9.35mm diameter, 26TPI) to thread a steel stub axel so it will fit inside a bike hub like a spindle (with cones from an old spindle) if anyone knows where i can find one of these please get in touch! :D PS i live in the UK

Question by ooda55   |  last reply

Does anyone know where I can get cardboard tube that is 6"-8" diameter?

I've tried carpet stores, but they're only about 4", so not big enough.  It's for something like this

Question by davidspd   |  last reply

Stirling engine displacer design? Answered

I am designing a gamma Stirling engine (this type) and I am unsure how long the piston should be and how long its stroke length should be the specs for the cylinder and piston pipes are below. The pipe for the cylinder is stainless steel. Wall thickness: 1.56mm Outer diameter: 31.7mm Inner diameter: 28.6 Length: 200mm (can be cut smaller) (Stainless steel cap will be welded to one end, the other end where the shaft comes out will be plugged with this nylon/graphite stuff) The pipe for the displacer piston is aluminium pipe.  Wall thickness: 1mm Outer diameter: 27.88mm Inner diameter: 25.88mm Length: ? (Two aluminium plugs will be used to seal its ends) How long should the piston, cylinder and stroke lengths be based on the specs?

Question by The MadScientist   |  last reply


I was wondering what to do with a parachute, when it opens its about 20 ft in diameter.

Question by Emsaid   |  last reply

How many chance for ...

Hi !How many chance for :- life appear on a planet with a moon- AND, seen from the surface of this planet, the diameter of this moon is almost the same than the diameter of the sun???I don't know, but chances must be very very very low ... We, Humans, must be very lucky =o)

Topic by chooseausername   |  last reply

Where to buy large glass tubes?

I need several glass tubes (10-20) that are around 30-40mm in diameter and 6 feet long. They also can't be rediculously expensive, I've been searching for a while, but all I've been able to find is glass with a length of 4 feet and a diameter of like 10mm. Any help?

Topic by guyfrom7up   |  last reply

What infomation are needed to calculate fps for an air canon? Answered

I know that fps is speed unit, and I'm trying to calculate the initial speed(or the power) for my air canon. Information I have: 1: value of the air chamber 2: psi 3: diameter of the barrel 4: length of the barrel 5: diameter of the air release valve will those information be enough? How to calculate fps or power from information above?

Question by    |  last reply

4mm buzzer

Hello everyone, I'm looking for a way to make (or hell even buy) a very small buzzer that can be rectangular or cylindrical that is 4mm in diameter and can be up to 10 mm long.  I've searched on Digi Key for something this small, but most things are about 8mm in diameter and 4mm long.  I need something skinny and long, not short and fat. Does anyone have any experience with this? Thanks

Topic by SJBoard44   |  last reply

What is the best soft iron disc thickness for 22mm x 3mm disc magnets

Hi, I am building a wind turbine with 12 , 22mm diameter x 3mm thick magnets on 6inch diameter soft iron disc and 9 coils on a wooden stator? Is the thickness of the soft iron magnet discs critical? Is 3.5 mm too thin or 10mm too thick?

Question by bulbwatt   |  last reply

Must find parts for CO2 gas project urgently please

I am currently working on a project that utilizes CO2 and tubing. The gas will be at <10psi, but due to the structure I must acquire two specific parts. Would anyone know exactly where I could purchase: - T-valves (0.1" outside diameter) - Check valves (0.1" outside diameter) They both must be able to withstand 10psi or higher. Thanks!

Topic by SubZero7   |  last reply

I want to generate energy with a motor.The size have importance or only the voltage matters?

I am building a project to generate eletricity with a motor. I want to know if the motor size(lenght, diameter, etc.) have inportance on the generated power or only the motor voltage matters? My motor: - 3,5cm diameter - 6,0cm lenght - 9,0v power Sorry the poor english... Thanks the help!

Question by XPProductions 

Plastic Optic Fiber

Hi, I made a lot of research in order to find some plastic optic fiber in europe, and I finaly add to buy some full rolls of the one I liked. It it PMMA fiber with 0.3dB/m light loss, it polish well, and when use with long length, gives a sligher yellow / green color to the light (noticeable on white light, but really lower than the other I've tryed). If someone need some, I can make a kit with : -27 meters of 0.75mm diameter -15 meters of 1.00mm diameter - 7 meters of 1.50mm diameter I think thati ncluding shipping to anywhere I can send it for tens euros. If someone is interested, let me know and I will check shipping price and paypal fees. Regards, tReg.

Topic by treg   |  last reply

Airsoft firing real bullets

Can an all-metal airsoft gun truly be modded to fire a .223cal round, as they are approximately the same diameter

Question by 5H4D03   |  last reply

What to do with caster wheels?

I have three caster wheels, 4cm in diameter, and don't know what to do with them.

Topic by Roger-X   |  last reply

Anyone know of a source for conductive rubber tubing?

Looking for 4-6 MM diameter or in that area. Also sheets. Small quanities.

Question by BubbaOkie   |  last reply

What should I encase these small speakers in?

Small 1.5 inch speakers (diameter), 1.3 inches tall

Question by Vijster1   |  last reply

What is this tool used for?

The slots align and are approximately 1/4-inch in diameter. The smaller piece has rollers and slides across the flat piece.

Question by FredrickF   |  last reply