SpudFiles

Hey guys, here's some info about my new cannon. Damage pics are coming soon!

Design Objectives:
I wanted to build a cannon that could do just about everything, and do it well. I wanted it to be quite powerful for its size, yet simple and practical. It needed to be relatively quiet, less than 8 feet in total length, cost less than 100 dollars and had to be constructed using only simple tools.

After some thought, I decided to make my cannon convertible from one with a ball valve and Schrader, to one with a union and quick-disconnect. I’m pretty sure that I’ll be using the ball valve the most, since it’s quieter, safer, and has smoother recoil when used with large projectiles. However, every once in a while I get the opportunity to go to the 21 acre family farm, where I can utilize my cannon’s full power with burst disks.

Materials:
(All of the PVC is Genova pressure-rated Sch40)

• 2" PVC pipe
  1.5" PVC pipe
  2x 2" 90 degree PVC elbows
  2" PVC threaded adapter
  2" x 1.5" PVC threaded bushing
  2" PVC threaded plug
  1.5" PVC threaded adapter
  American Value 1.5" ball valve
  American Value 1.5" PVC Union (rated up to 150 psi)
  2x 1.5" galvanized steel nipples
  Victor Metal Tubeless tire valve (rated up to 150 psi)
  2x 6" stainless steel hose clamps
  Grip liner (to hold the barrel braces in place)
  1" x 3" board

P.S. I'm rather new to using forums, so my post might be a bit strange-looking.

Thats a nice, clean launcher you got there, but why not put the BV behind the union? You could then choose whether or not to use a disk, but it would be much more powerful with the disk in.

I thought about that. I can put another steel nipple between the ball valve and the union if I want to use it in that configuration.

That is one clean build. Did you use primer? I would add a pressure gauge, other than that, very nice!! I love the name, L O L ! :wav:

Thanks for the complements guys! I used clear primer and I didn't add a gauge because I'm going to equalize the pressure in my compressor (which has a guage) and my cannon.

clean build, you should make a barrel that utilizes a burst disk puncturing mechanism so that when you're in the right place for burst disks, you can attach the barrel and have a burst disk launcher with a trigger

should give some decent power with a burst disk, needs some amusing decoration though:

you should make a barrel that utilizes a burst disk puncturing mechanism

Any suggestions on doing this? I couldn't much in the How-To and pneumatic discussion sections.

danielrowell wrote:Any suggestions on doing this? I couldn't much in the How-To and pneumatic discussion sections.

A triggered burst disk is pretty well explained in the wiki: http://www.spudfiles.com/spud_wiki/inde ... burst_disk

You need two unions, a tee and some sort momentary firing valve like a blowgun.

Any suggestions on doing this? I couldn't much in the How-To and pneumatic discussion sections.

I've tried the resistance heating and the mechanical puncture but never the double burst disk one... Way to complicated. The resistance heating worked the best for me. I drilled 2 tiny holes in the union(right on top of the burst disk) then ran a wire through(I don't now wat type) well you know how to do the rest. Make sure to use a relatively strong wire and not too much current becaue you don't want to replace the wire every time you fire

pneumaticcannons wrote:

Any suggestions on doing this? I couldn't much in the How-To and pneumatic discussion sections.

I've tried the resistance heating and the mechanical puncture but never the double burst disk one... Way to complicated. The resistance heating worked the best for me. I drilled 2 tiny holes in the union(right on top of the burst disk) then ran a wire through(I don't now wat type) well you know how to do the rest. Make sure to use a relatively strong wire and not too much current becaue you don't want to replace the wire every time you fire

This is a good example of how to make a simple cascading burst disc launcher.

They are so simple, even the wiki says so

Thanks again guys! I'm still a bit of a noob when it comes to building and designing cannons, so your expertise is greatly appreciated.

I think I might try the resistance heating idea, as it will cut down on the reloading time somewhat.

On a side note, my next project is going to be a good bit more ambitious, but it will give me some experience in making pistons and will result in a more unique cannon. It's probably going to be a golfball-launching coaxial, fired bazooka-style, with a barrel-sealing piston and qev pilot valve.

UPDATE: PYKRETE ROUNDS

After a bit of thinking, I came up with the idea of using pykrete for ammo. I thought my idea was rather original, but learned a few minutes later that, of course, it's already been discussed on this forum.

I don't have any damage pics of these rounds yet, but after molding and testing a round using paper towels as the reinforcing medium, I have concluded that these rounds are very well-suited for use as PC ammo. They're cheap, biodegradable, retain their integrity when launched out of powerful cannons, transfer almost all of their energy into the target, and can be easily molded to fit any cannon. The only problem is that they take some time to make.

For those of you who don't know what pykrete is, by definition, it's a frozen material made up of 14% wood pulp and 86% water by weight that has properties more like concrete than ice. However, I found that cotton makes a very good substitute for wood pulp and I'm currently testing to see how it compares. Expect damage pics soon.

NOTE: Choose your targets carefully when using pykrete projectiles. If the round doesn't penetrate the target or hit it head on, there's a good chance that it will ricochet. Yes, it's that tough.