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ball bearing / marble piston

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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ball bearing / marble piston

Unread postAuthor: spud-tom » Sun Jun 03, 2007 12:36 am

does anyone think that it is possible to make a coaxial with a marble? In my opinion, since it would be pretty heavy and it would rest on the pipe, as the air is pressurized, it would put the marble against the barrel - sealing it. Can you help me out and post some comment or ideas? Thanks.
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Unread postAuthor: singularity » Sun Jun 03, 2007 12:43 am

there was a min coaxial "pen gun" that used an airsoft bb for a piston he won second place in the spud gun build off, check the spudfiles home page you'll see it
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be sure to check out my <a href="http://www.spudfiles.com/forums/ak-style-airsoft-vortex-gun-t10959.html">AK Styled Vortex Gun</a> and my <a href="http://www.spudfiles.com/forums/at-4-t9627.html">AT-4 Rocket</a>

upcoming projects... finalized clip fed BBMG and ball point pen sniper
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Unread postAuthor: spud-tom » Sun Jun 03, 2007 12:45 am

yea, i saw the post but didn't that guy say that he "thought" about putting the bb in, but to be safe he just went along with a normal piston?
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Unread postAuthor: hi » Sun Jun 03, 2007 1:07 am

the bb is the piston. there is a gasket on the barrel to seal it.

to answer your question, yes, it could be the piston.
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"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

you know you are not an engineer if you have to remind yourself "left loosy righty tighty"
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Unread postAuthor: spud-tom » Sun Jun 03, 2007 9:50 pm

thanks guys, any ideas of balls bigger than a bb, smaller than golf ball - like a marble, but lighter
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Unread postAuthor: VH_man » Sun Jun 03, 2007 9:55 pm

www.mcmaster.com. search balls. youll find what youre looking for, garunteed. its where i get my steel 6mm air(hard) bb's. you can buy basically ANY size. find one that matches the ID of the tube youre using. i want to see this work, it makes sense that a ball would work well as a piston. never gets jammed :)
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Unread postAuthor: jackssmirkingrevenge » Sun Jun 03, 2007 10:03 pm

spud-tom wrote:yea, i saw the post but didn't that guy say that he "thought" about putting the bb in, but to be safe he just went along with a normal piston?


I did this because my method of epoxy construction basically cannot be dismantled, only destroyed, so I figured I'd go with something I knew would work rather than experimenting.

If your tolerances were tight enough however I'm sure this would work well - you need to match your ball o/d to the chamber i/d very well though.
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Unread postAuthor: hi » Sun Jun 03, 2007 10:08 pm

would a solid rubber ball work? that way you wouldnt need a seal face because the piston is the seal face?
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"physics, gravity, and law enforcement are the only things that prevent me from operating at my full potential" - not sure, but i like the quote

you know you are not an engineer if you have to remind yourself "left loosy righty tighty"
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Unread postAuthor: jackssmirkingrevenge » Sun Jun 03, 2007 10:14 pm

hi wrote:would a solid rubber ball work? that way you wouldnt need a seal face because the piston is the seal face?


Good idea, though it might cause problems in the long term as the rubber is always presenting a different face to the barrel edges which would cause uneven wear - but if you can access the ball and replace it this won't be an issue.
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Unread postAuthor: pyromaniac » Sun Jun 03, 2007 10:20 pm

what about a mouse ball in 3/4?
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:pottytrain3:
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Unread postAuthor: spud-tom » Sun Jun 03, 2007 10:29 pm

yea, i'm thinking of making a coaxial with a ball, (and making it fully accessible by just taking threaded pipe and sealing it with teflon tape) I like the rubber ball idea thought.


Merged:


what do you think about the Buna-N rubber Balls from McMaster?
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