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diaphram/piston coaxial

Unread postPosted: Thu Jul 05, 2007 1:23 am
Author: origin unknown
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.

Unread postPosted: Thu Jul 05, 2007 2:14 am
Author: spud yeti
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!? :D
Really good work though!

Unread postPosted: Thu Jul 05, 2007 2:17 am
Author: Mitchza89
Thats a great looking Coax there.

Unread postPosted: Thu Jul 05, 2007 2:32 am
Author: origin unknown
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!? :D
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.

Unread postPosted: Thu Jul 05, 2007 3:08 am
Author: spud yeti
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 :D )

Unread postPosted: Thu Jul 05, 2007 10:39 am
Author: noname
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. :D

Unread postPosted: Thu Jul 05, 2007 11:04 am
Author: spud yeti
Sounds logical. So you think it works the best then? (to have both piston and diaphram)

Unread postPosted: Thu Jul 05, 2007 11:16 am
Author: noname
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.

Unread postPosted: Thu Jul 05, 2007 11:48 am
Author: hi
nice. what did you get the rubber from and what did you cut it with? its a great looking gun you got.

Unread postPosted: Thu Jul 05, 2007 1:03 pm
Author: noname
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.

Unread postPosted: Thu Jul 05, 2007 2:31 pm
Author: origin unknown
I used these nice Fiskars scissors that are used to cut thicker materials, especially bushes and small branches.

Unread postPosted: Thu Jul 19, 2007 8:20 pm
Author: e1337
I like the cannon, but how did you melt and mold the piston?

Unread postPosted: Sun Jul 22, 2007 4:28 pm
Author: origin unknown
I sprayed the inside of the pipe my piston was in with cooking spray and squirted the hot glue in. It is quite simple...

Unread postPosted: Wed Jul 25, 2007 2:31 pm
Author: spud yeti
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?

Unread postPosted: Fri Jul 27, 2007 6:00 pm
Author: origin unknown
I melted it through the glue gun.