SpudFiles

This started out as a diaphram cannon, but later on I decided to create a piston for it to see if it would perform any better. Now I have a gun that can be used as a diaphram or a piston gun using the benifits of both valves, and I believe I am the first to do this.

SPECS
chamber: 1.5" sch40 pvc
barrel: 0.5" sch40 pvc
valve: selectable; diaphram or piston
pilot valve: modded blowgun w/ ball valve safety
fill valve: screw-in schrader or a check valve attached to coupler nipple

My diaphram is made of 1/8" sheet rubber, and it fits between a male adaptor and a female adaptor. My piston, which fits inside the male adapter, is made of hot glue and it has a neoprene sealing face. My diaphram works great, it shot a medium weight projectile about 100 ft upwards pointing the launcher straight up. The piston did work, It just didn't open fast enough to let a sufficient amount of air come out the barrel. This problem could easily be fixed, by using a larger pilot opposed to my smaller modded blowgun. This is my first gun with a completely homade valve, and I am very proud of it. I plan to be making a barrel sealing piston valve with 1.5" porting all housed in a 2" T, but it won't be started for a while.

That looks like a really cool little cannon you have there! I love how it is interchangeable too! As I was looking at your gun, I thought of something... What if you had both the piston and the diaphram in?? You would have the sealing power of the piston and opening speed of the diaphram! Just a thought though, so why dont you try it and see!?
Really good work though!

Thats a great looking Coax there.

spud yeti wrote:That looks like a really cool little cannon you have there! I love how it is interchangeable too! As I was looking at your gun, I thought of something... What if you had both the piston and the diaphram in?? You would have the sealing power of the piston and opening speed of the diaphram! Just a thought though, so why dont you try it and see!?
Really good work though!

The only way to combine the two would have one piloting the other. I would have to build a different gun to test that. Maybe a homemade diaphram piloting a piston... that would be interesting because most people use sprinkler valves or QEVs to pilot their piston, not anything homemade.

Yeah, thats a really good idea, and could be fun to experiment with! Maybe you could sketch a few plans and I'll do like wise and we'll see what comes out! I have loads of time (school holidays).
back on topic though: nice cannon! (Im trying not to hijack threads )

A couple months ago I made a coaxial that used either a piston or a diaphragm, along with a combination of both, that allowed it to open extremely fast and then slam back and allow full flow.
Nice gun.

Sounds logical. So you think it works the best then? (to have both piston and diaphram)

I don't have a chrony, but in order, damage-wise, the piston was worst (shot through one side of a can), diaphragm was second, (shot through one side and split open the other side), and the combination shot through both sides and dented my shed.

nice. what did you get the rubber from and what did you cut it with? its a great looking gun you got.

I just get 1/8" and 1/16" sheet rubber from Ace Hardware. I can usually cut it with huge scissors, but I need an exacto knife sometimes.

I used these nice Fiskars scissors that are used to cut thicker materials, especially bushes and small branches.

I like the cannon, but how did you melt and mold the piston?

I sprayed the inside of the pipe my piston was in with cooking spray and squirted the hot glue in. It is quite simple...

Another method: cooking oil works well, but if you having trouble with it you can also use greased up baking paper around the inside of the pipe, this increases flow quite nicely too.
Did you melt the glue through the gun or microwave it or what though?

I melted it through the glue gun.