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Supah-Valve Imitation

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Supah-Valve Imitation

Unread postAuthor: mark.f » Sat Aug 02, 2008 9:55 am

Well, I was bored last night, again, and decided to draw up this imitation supah valve.

It's a chamber sealing valve, but I designed it in a way to not require specialized tools (like a lathe to cut O-ring grooves and trim down a piston). All that's required is a belt-sander, hacksaw, and other minor tools that everybody should have access to.

The image is below.

The brown is a 3" tee.
The yellow is a 3x2" threaded bushing (3" spigot x 2" FNPT)
The red is a 3x2" slip bushing (3" spigot x 2" slip)
The dark blue is a length of 2" SCH-40
All the black is rubber. Individual parts explained below.
All the gray is steel hardware. Individual parts explained below.
The white part is a 2" endcap.
The green part is some 3" SCH-40.
The light blue is a 3x1.5" slip bushing.
The purple is a 1.5x.75 threaded bushing.


Here's the rundown.

From left to right, the seals (rubber, represented by black), are: chamber sealing gasket (piston face), endcap sealing gasket (seals endcap to test plug), 3" test plug, bumper, and service port sealing gasket (the two are represented as one part in the drawing).

The test plug serves as the piston. As it is tightened, the rubber part expands to fill the pipe, forming a seal that, when lubricated, should work fine as a piston seal. Two test plugs need to be bought, though. Each comes with two metal ends, one larger than the other, to push against the outside of the pipe. All the ends are removed, and one rubber core is reassembled with two of the smaller metal faces, so that the plug will fit all the way inside of the pipe. Some 5/16" threaded rod (same size as the bolt through the original test plug), is used to both tighten the plug and attach the 2" endcap as the sealing extension. An equalization hole is drilled through the endcap and test plug, and the endcap is sealed onto the test plug with a small gasket.

The 3" pipe needs to be sanded down in diameter at the end to fit over the stop in the 3" tee. Don't say "You need a lathe to do that!", because I have done it with a belt sander before to make a barrel-sealer.

Finally, on the matter of the bushings. First, the hex part of the bushings is sanded down to the cylindrical profile of the rest of the bushing. Then, they are trimmed in length. For the top bushing (barrel connection), the end (inside) is trimmed the length of the hex ridge removed. For the left (chamber connection), the end is trimmed the length of the trimmed slip bushing inside, which is itself trimmed to about half the socket depth of the tee.

The 3x1.5" bushing on the right is trimmed to about 1/3 of the tee socket depth. Care needs to be taken to buy a bushing that is of solid construction on the outside, and not ribbed like some, as when you trim these, you will be left with holes (bad). Then, the 3/4" bushing has it's hex removed and trimmed the length of the hex ridge. Both are solvent welded together, but DO NOT solvent weld them into the tee.

For connection into the tee, the bushing assembly is attached by about 8 1/4"-20 machine screws, spaced evenly and, for aesthetics, in one line, not crooked. Before drilling and tapping, assemble the rest of the valve. Then, when you're ready to seal the valve up, place on a hard flat surface with the chamber port down. Place the bushing on top of the service port sealing gasket (about 1/8" neoprene), and then set one or two 25 pound weights on top of it (depending on the hardness of the rubber gasket). While the gasket is depressed, drill and tap the holes for the screws, and then fasten the bushing assembly in place with the machine screws. You are now set.


I drew this drawing roughly to scale (but taking the measurements in hundredths of inches and dividing by four to get the number of pixels), but rounding and approximation were used heavily, so it is best to lift measurements from the parts you yourself order to build this valve. I intended this to be helpful for anybody wanted to build a Supah-valve imitation, and those interested in building chamber-sealing valves without special tooling. Good luck.
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This is a valve schematic, roughly to scale.
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Unread postAuthor: PVC Arsenal 17 » Sat Aug 02, 2008 10:35 am

Instead of using a belt sander to take down the pipe, why don't you just bore out the stop using a hole saw? There is a size for every pipe socket. I've done it plenty times. It makes a bit of a rough cut but a little sanding and it's perfect.
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Unread postAuthor: Mr.Sandman » Sat Aug 02, 2008 10:55 am

oh crap i feel really dumb now :x i for years thought a supah-valve was a barrel sealing valve :oops: Oh well i wonder what else ive been wrong about:roll:
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Unread postAuthor: mark.f » Sat Aug 02, 2008 11:48 am

PVC Arsenal 17 wrote:Instead of using a belt sander to take down the pipe, why don't you just bore out the stop using a hole saw? There is a size for every pipe socket. I've done it plenty times. It makes a bit of a rough cut but a little sanding and it's perfect.


That was my original idea, but that big of a hole saw is pretty expensive, and it's not that common, so you can usually find somebody to borrow one from. Everybody at least knows somebody who has a belt sander or bench grinder. But that is an option if you happen to have a 3.5" hole saw or know somebody who does.
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Unread postAuthor: starman » Sat Aug 02, 2008 12:03 pm

This is great Mark. Thanks! I just bookmarked this for future reference.

Do you have access one of the real supahs? It seems like many years ago, the supah's drawings were publicly posted over at Spudtech, and later pulled.

BTW, what's all this retiring from Spudfiles talk you were talking about just a month ago. Looks like this stuff is still flowing through you....use the force Mark..... :lol:
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Unread postAuthor: frankrede » Sat Aug 02, 2008 12:18 pm

starman wrote:This is great Mark. Thanks! I just bookmarked this for future reference.

I seconded that.
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Unread postAuthor: clide » Sat Aug 02, 2008 12:41 pm

starman wrote:Do you have access one of the real supahs? It seems like many years ago, the supah's drawings were publicly posted over at Spudtech, and later pulled.


And later put back up here
http://www.spudfiles.com/spud_wiki/inde ... upah-Valve

Looks good mark, have you actually tried this method before?
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Unread postAuthor: socoj2 » Sat Aug 02, 2008 2:55 pm

Ill trade you a Asco 1.5" pulse for one of these?
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Unread postAuthor: mark.f » Sat Aug 02, 2008 9:04 pm

starman wrote:BTW, what's all this retiring from Spudfiles talk you were talking about just a month ago. Looks like this stuff is still flowing through you....


I wasn't "retiring" from spudtech, I was just liquidating my arsenal, commenting that I probably couldn't build many more cannons now that I'm living in a tiny apartment near campus. I said I'd still hang around and post, and what's space-taking about some designs and a small piston valve?

clide wrote:Looks good mark, have you actually tried this method before?


If you mean the test-plug as a piston, I used it in a sort of Gen. II prototype tank that used compressed air instead of water. The propane mix stayed ignitable (signaling no large air leaks into the mix), so I'm assuming it would seal off decently to make a chamber-sealing valve. I was also using a silicone spray lubricant as well. This was a slightly larger plug as well (4"), so there may be some problems with keeping the plug straight and square inside of the carriage pipe.

If you mean the fancy bushings and cut down pipe, I've used it on a piston valve I made for our robotics team (that they never got around to using, but I tested before I gave it to them). It's a lot more difficult and iffy than just using standard fittings and letting the valve bulk up a little, but if done right it looks nice and will work just as well as it looks.

socoj2 wrote:Ill trade you a Asco 1.5" pulse for one of these?


I'm not mass-producing or selling these or anything, I'm just putting up the designs for other people's reference and to show what I'm working on. Besides, bit for bit, a barrel-sealer constructed to the same sealing and equalization standards as this valve would most probably outperform this valve (see the Wiki article on the Mauler valve for an analog).
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Unread postAuthor: Hotwired » Sat Aug 02, 2008 10:01 pm

I drew this drawing roughly to scale (but taking the measurements in hundredths of inches and dividing by four to get the number of pixels)


Whatever gets your spudgun built but yargh...

I sketch in MSPaint at 1mm = 1pix

Calculations required to draw a line = nil


Join the DARK SIDE, we have METRIC :twisted:
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Unread postAuthor: Mr.Sandman » Sat Aug 02, 2008 10:46 pm

doesnt a supah valve use a different looking piston?
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Yeah, it's that important.
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Unread postAuthor: frankrede » Sun Aug 03, 2008 12:23 am

Mr.Sandman wrote:doesnt a supah valve use a different looking piston?

Imitation* Not clone
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Unread postAuthor: starman » Sun Aug 03, 2008 12:47 am

clide wrote:
starman wrote:Do you have access one of the real supahs? It seems like many years ago, the supah's drawings were publicly posted over at Spudtech, and later pulled.


And later put back up here
http://www.spudfiles.com/spud_wiki/inde ... upah-Valve


Ahh, Thanks Clide!
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