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Aluminum Rod In a Two Piece Piston

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Aluminum Rod In a Two Piece Piston

Unread postAuthor: Mr.Tallahassee » Mon Jul 11, 2011 10:35 pm

I was wondering If I could use a 3/16'' aluminum rod in a piston valve. I already have the rod from a previous project and it would be MUCH lighter than a solid piston. I'm looking at 2'' because i have a 1.5'' chamber and 1'' barrel and it would give me some wiggle room on size. BTW the check valve was out on the wrong design.


EDIT: I corrected the image
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Unread postAuthor: Gun Freak » Mon Jul 11, 2011 10:52 pm

That's really thin for a 2" valve... I used 5/16 threaded rod in my 2 inchers and it is fine, but I'm not sure how much smaller you can go.
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Unread postAuthor: Mr.Tallahassee » Mon Jul 11, 2011 11:06 pm

Yeah, I DO have a .25'' steel rod but that's ammo for my gun. I guess i can sacrifice 6 or 7 inches of it since it IS 2 feet long.
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Unread postAuthor: Gun Freak » Mon Jul 11, 2011 11:23 pm

Your diagram looks good, you might wanna try the threaded rod piston.
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Unread postAuthor: Moonbogg » Mon Jul 11, 2011 11:24 pm

3/16 aluminum rod seems a bit flimsy to me for a piston that large. It might work though, you can always try and then replace it if it bends or something.
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Unread postAuthor: Mr.Tallahassee » Mon Jul 11, 2011 11:31 pm

Gun Freak wrote:Your diagram looks good, you might wanna try the threaded rod piston.
Thanks, I'm going to thread a steel rod I JUST found. It's precisely 0.311'' in diameter and 6.5 long.
Always happens, you find what you're looking for AFTER you stop looking for it. :lol:
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Unread postAuthor: al-xg » Tue Jul 12, 2011 5:19 am

All rod bending aside, you need to make sure there is enough bearing surface on the large end of the piston so that it will stay centred and seat properly.

You can also get rid of the bit of "inner" barrel which would give you some more volume and better flow.

Could you not fill from behind the piston ? Just cut a little groove to make the O-ring only let air through in one direction.
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Unread postAuthor: Mr.Tallahassee » Tue Jul 12, 2011 10:59 pm

Does anyone have any ideas on making threading this stainless steel rod easier? I'm very limited on tools. (Vice-Grips, tap and die set, grinding tools)
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Unread postAuthor: Gippeto » Tue Jul 12, 2011 11:13 pm

Stainless is a bit of a ....female doggy to cut threads on with a die (or in with a tap). If you MUST...start it STRAIGHT, go slow, break the chips often, and use a quality tap cutting fluid intended for stainless.

Not sure what you have, but 300 series (common around here) stainless work hardens rather easily if you let it get too hot...usually a result of going too fast, or insufficient coolant. Keep it cool, and it machines beautifully. :)

A LOT less grief to simply go to the hardware store and get a piece of all thread. :idea:
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Unread postAuthor: Mr.Tallahassee » Wed Jul 13, 2011 12:02 am

Gippeto wrote:A LOT less grief to simply go to the hardware store and get a piece of all thread. :idea:
As much as I'd love to, I'm 17, broke, and unsuccessful at finding a job. minimizing cost is an absolute MUST.
Keep it cool, and it machines beautifully. :)
Yes it does. More reason to work with it! :D It's just BRUTAL work.
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Unread postAuthor: Gun Freak » Wed Jul 13, 2011 5:46 am

Piece of all thread=2 dollars.
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