Instructables

The __jrP4__ - Junior Portable Pnuematic Projectile Propogator

I have wanted to make something like this for a long time, but couldn't quite figure it out. Thank you to Scott Scriven - http://toykeeper.net/spud/ - for the idea.

Here was my goal:
1) Handheld
2) Air powered (relatively safe)

Enjoy!!!
 
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Step 1: Plan and gather parts

Picture of Plan and gather parts
Parts list:

A. ~ 2' of 1/2" pvc (schd 40 or 80).
B. ~ 1' of 1 1/2" pvc (schd 40 or 80).
C. Some combination of fittings to go from 1/2" FS (female slip) to 1 1/2" FS. I picked up a few different combination of fittings, each of them producing a little different look. For this gun used a 1/2"FS x 1 1/2"MS and a 1 1/2" FSxFS.
D. 1 1/2" FS x 1 1/2" FT (female threaded).
E. Some combo of pieces to go 1 1/2" MT x 3/4" FT. I found a single fitting for this, but you may have to use multiple.
F. 3/4" MT x 3/4" FT elbow.
G. 3/4" MT end cap.
H. Two tank valves.
I. What they call a "Valve extender". This fits onto the tank valves and has a plunger to release the air. I have some other ideas on what else could replace this, but this is the most straight forward method.
J. Some semi-flexible rubber (or maybe plastic) material for the diaphram. I used some sheet gasket material.
K. Teflon pipe tape (not shown).
L. PVC cement (clear is best, to keep it looking clean).

You will need a drill and a tap set also. To thread for the tank valve, you need a 21/64 drill bit and 1/8-27 NPT tap head.

Step 2: Build firing chamber

This was the eastiest part of the assembly:

1) Cut (B) to the desired length. I went for about 8".
2) Cement (C) to (B). Cement (D) to the other end of the (B-C) assembly.
DanTDM10 months ago

I used galvanized

immell_995 years ago
what exactly did u use 4ur diaphram?
dschwant (author)  immell_995 years ago
It is rubber a little less than 1/8 in thick. I think you can get it in the plumbing supplies, but I just had it sitting around in the garage.
knoxarama5 years ago
yes, yes there are. But there are also funner ways which are incredibly dangerous and reletively idiotic. Either way, cheese wins Except it must first betray wisconsin to stupid cheese heads
JoeyJaroz7 years ago
I Got the same computer ITS SO GREAT!!! also good instructable
SheenJones7 years ago
i have seen it many times, and still dont get it. what is the PVC ring with the blue ring? what is the blue ring?
dschwant (author)  SheenJones7 years ago
Do you mean the roll of teflon (R) tape - used to seal the pvc thread fittings?
well is that the blue thing? what is teflon tape for? and why is it in that peice of PVC?
dschwant (author)  SheenJones7 years ago
Yes, that is a spool of teflon tape. The white piece around it is the cover for the tape spool (plastic but not PVC). Anytime you put a PVC threaded joint together, you should use teflon tape. The tape should be wrapped in a clockwise direction on the male fitting - to match how the threads will grab tape. They make special tape (yellow?) if you are using PVC for gas (natural or propane), but for normal water or electrical PVC the white tape is the thing to use.
oh, okay. thank you. so you can just get it like at a hardware store? thanks for your help. lol.
Pattycakes8 years ago
I made something like this but way bigger, took 10 min. to pump up, and could blow babies apart at 20 feet.
Babies you say...........
genewitch8 years ago
I made several potato cannons... after reading about them online several years ago we decided that the sprinkler valve model would suit us best. If i can find pictures i'll upload them the thing looked harsh, it was 6 feet of tubing with a U shape, so only three foot total length. the chamber to hold the air was 2.5" by three foot, with the stuff to bring it down to the 1" tubing used by the valve. the valve had a 24 volt solinoid, i think it was supposed to be AC 24V, but we used 4 9V batteries hooked up to be 18V X2 in parallel. the switch was just a dinky pushbutton. the batteries and the pushbutton were mounted inside of a 2" PVC section that was then taped and later glued to the barrel. the barrel was either a 3/4" or 1" 2' long pvc pipe. i can't recall anymore. anyhow the chamber had a threaded bicylce tire nipple on it, and you'd charge it to 120PSI. load your ammunition into the barrel and push it down. SLing it over your shoulder, aim down the chamber and press the button, and FFFFFFFFFFFFWOOOMP, out came your projectile. the only method i've seen that's better for the pneumatic ones is using a diaphragm, but i could never figure out the instructions for those types. My favorite potato gun ever was one we made out of a 2 liter fire extinguiser and a length of exhaust pipe (from a car). We epoxied the two together, them wrapped heavy duty duct tape around the entire thing. drill a hole at the bottom of the fire extinguisher, and pour in your naptha (lighter fluid). spin the thing in the air horizontally to allow the mixture to get more oxygen, load it with an orange or whatever you want, set it on the ground and light it with a BBQ lighter. man that thing is loud, and it sent oranges sailing 2-3 blocks away if you aimed it right. :-D
The best and easiest potato cannon I ever put together was just a straight cylinder with about a foot and a half of 6 inch diameter PVC joined to 2 feet of 3 inch. I capped the big end with a screw cap so that it can be removed and inserted a pezioelectric grill ignitor. Sealed all of the joints, wrapped the combustion chamber in duct tape to control shrapnel as these will occassionally explode as you up the anti, and it was done. Jam a potato (an apple is a softer projectile, and a balled sock will just knock the wind out of someone at close range) on the end, use a pole to force it to the beginning of the barrel (at the end of the combustion chamber), and you're almost done. The most important part is the fuel. Anything combustible works. Hairspray, starter fluid, paint, whatever. Airisol is easiest. However, for the potentially dangerously powerful result, you need to generate dry-particle spontanious combustion. Degree brand airasol deoderant works the best for me. Unscrew the end, spray for just a second, definately not as long as two or the fuel mix ratio starts to go, quickly recap, and press the button. I've put a potato through a quarter-inch piece of plywood with this design.
mr inventa8 years ago
again see how stupid i am! haha i accidently put "right" instead of "write" lol just gotta take that english class one more time...
mr inventa8 years ago
srry guys im new to this! first awsome instructions although why do you need the 2 inch 1/2 foot piece of pipe and sec. how do you load the ammo, third where can i find these valves ive asked evryone!! i even went to lowes & home depot but no one knows what im talking about! i feel so stupid :/ lollololo. ok enough drama but anyways can someone right back explaining atleast one of these ques.?
Retroboy48 years ago
I made a bigger diaphram valve type model a few years back, this is much more portable and compare faveribly to the biggergun.
Camster9118 years ago
Lol! loving the sound it makes
vatik8 years ago
cool project. I made something similar to this a few years back. It wasn't quite as portable as I used a tire valve and a automotive air pump. I put a potatoe halfway through a wheelburrow at about 175 psi..... if anyone tries this modification, make sure to check the pressure ratings on your pvc (i think mine was rated for 250). too much pressure and you could end up with plastic shrapnel in your head. pneumatic guns can be quite powerful at higher pressures.... use caution.
woofo8 years ago
Great project! I tried to do something like this last year using an old pop gun design but modified to fire wine corks. Living in the wine country we got lots of those! Could be fun. I like your design. how's the valve work?
dschwant (author)  woofo8 years ago
The valve extender works fine. It probably doesn't let enough pressure out quickly enough. I have the parts to try fitting a air gun (like you use to cblow stuff off with compressed air) handle, then it would have a trigger.
dschwant (author)  woofo8 years ago
The valve extender works fine. It probably doesn't let enough pressure out quickly enough. I have the parts to try fitting a air gun (like you use to cblow stuff off with compressed air) handle, then it would have a trigger.
Awesome project, I've always wanted to build a larger cannon with the diaphram valve...never had a decent air compressor though :- ( Very good write-up, clear instructions, good pictures...Thanks!
Moogle8 years ago
Sweet! Now I have something productive to do other than read instructables all evening! BTW, you can make a functional impromptu tap (or die?) for whatever size you need by buying a small length of threaded tube of the appropriate size, cutting several slots perpendicular to the threading, and squeezing the end slightly smaller with a pair of pliers. Then just grip the other end really hard w/ the pliers and use it like a normal tap. My dad demonstrated this when I asked for help with my big potato gun. He didn't have a 1' tap handy in his workshop. I'll make a short project on it if I ever get around to making one of these tater-tot guns. Such a neat firing mechanism!
colin8 years ago
This is awesome. Very clear instructions and great pictures. What are you using for projectiles?
dschwant (author)  colin8 years ago
Mainly just paper wads. Mini marshmellows work too. A paint ball seems to be the right size, but I haven't tried it yet.