Small coaxial

Show us your pneumatic spud gun! Discuss pneumatic (compressed gas) powered potato guns and related accessories. Valve types, actuation, pipe, materials, fittings, compressors, safety, gas choices, and more.
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Sat Oct 27, 2007 5:14 am

Seems a bit short to me, however not having completed a pneumo it may work fine. I just tend to think it *might* have troubles sliding freely.
Meh, what do i know!? Best wait for the experts to reply :wink:
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rixth
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Sat Oct 27, 2007 5:24 am

May have found something even better.

See image. b is 52.9mm, c is 55mm

Perfect width, and length!

http://www.hansenproducts.co.nz/product ... s/SMHT.jpg
I'd have to chop the thread off though
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Last edited by rixth on Sat Oct 27, 2007 6:12 am, edited 1 time in total.
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Sat Oct 27, 2007 5:40 am

Now that sounds like the go :wink:
America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.
rixth
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Sun Oct 28, 2007 11:54 pm

I swear to God I'm going to kill someone....

I'm going MENTAL. I can't get the barrel to seal (yes this is my first piston valve)...

I've tried a couple different pistons, as well as trying putting fabric or a disk of hot glue behind it (as in http://www.spudfiles.com/forums/files/untitled2_531.jpg). Whenever I pump, air just escapes out the barrel. I've tried manually pressing the piston up against the barrel, then filling it but it still escapes.

The sealing face is a disc cut out of a neoprene gumboot (for you yanks, this is what a gumboot is: http://en.wikipedia.org/wiki/Image:Wellies.jpg ). It's maybe 2mm (0.07in) thick.
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Mitchza89
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Mon Oct 29, 2007 12:04 am

Hmm thats a tough one mate but I reckon the face on the barrel might be abit wonky. That was the problem I had. Just place some fine wet n dry sandpaper down on a table and rub the face against it. That should smooth out any irregularities.
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Mon Oct 29, 2007 12:13 am

I checked the face, I think the rubber might be a bit hard. What is typically used as a sealing face? I know it's neoprene, but I don't think it's what I have.
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Mon Oct 29, 2007 12:13 am

It may be that the gumboot material is too hard. Try a different kind of rubber.
America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.
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jackssmirkingrevenge
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Mon Oct 29, 2007 12:18 am

One of the best sources of rubber is a car or bicycle inner tube, I'm sure you can easily get your hands on one.

Also, make sure that the sealing end of your barrel is 100% flat, smooth and parallel to the sealing face of your piston.
hectmarr wrote:You have to make many weapons, because this field is long and short life
rixth
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Mon Oct 29, 2007 1:21 am

Well, all the air escaping was my fault, but lets not go into that.

Now I've fixed that, but when I take the pressure past 20, it lets anything more out the barrel. Is this another sign of a poor seal?
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jackssmirkingrevenge
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Mon Oct 29, 2007 1:36 am

How is the sealing face attached to the piston?
hectmarr wrote:You have to make many weapons, because this field is long and short life
rixth
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Mon Oct 29, 2007 1:44 am

A bolt in the middle
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Mon Oct 29, 2007 1:48 am

Is the piston filled with anything? If not the rubber might be getting pushed into the piston under pressure.
America, the greatest gangster of all time. With 200 million odd foot soldiers at it's whim and call.
When you fill your car with refined oil remember that it has been paid for with blood and guts, some from your own countrymen, most not.
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MrCrowley
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Mon Oct 29, 2007 1:53 am

The bolt could be leaking, chuck some epoxy on covering up the bolt and the test it.
rixth
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Mon Oct 29, 2007 1:56 am

The piston isn't filled at this stage.

I'll go epoxy the bolt now though
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Mon Oct 29, 2007 1:58 am

is there a washer between the bolt and the rubber?
hectmarr wrote:You have to make many weapons, because this field is long and short life
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