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Help with piston

Post about things you have launched or thought about launching. Also post about various materials used for building cannons. No posts about explosive projectiles!
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Unread postAuthor: hi » Fri Apr 06, 2007 1:42 pm

You have a 1'' barrel, therefor, you need a 1.5'' tee. you need a bushing that goes from 1.5 inch to 1 inch. You need to cut about 4 inches off of your barrel, or use 4 inches of 1'' copper pipe. the 1'' pipe now needs to go completely through the bushing and into the tee. the 1'' pipe needs to be in the center of the tee, about half way in. solder the pipe to the bushing and solder the bushing to the tee. on the other end of the tee you need to solder about 3 inches of 1.5'' copper pipe into the tee. the piston sits in that pipe. this will allow you to put a threaded adapter and plug on the 1.5'' pipe along with a plug. the piston sits in the 1.5'' pipe. you can now service the piston if you need to.

you can use the piston that you have, if you can make it fit into 1.5'' pipe. if you cant then a cheap alternative that works very well for me if to mold one out of hot glue sticks.
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Unread postAuthor: spudthug » Fri Apr 06, 2007 1:56 pm

yo hi, my dad is gona use a lathe to do al this but he doesnt quit understand...can u draw up a diagram??only if ur willing to if ur not its ok...if he doesnt can someone else because we know how it works but to do it we r gonna need some diagrams
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4" piston valved cannon-half done..( i spilt my cement...)

Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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Unread postAuthor: spudthug » Fri Apr 06, 2007 2:17 pm

wait i think i got it...to make the change this is all i would need right??correct me please if im wrong


Parts:

copper

1. 1.5" pipe few inches long

2. 1.5x1" bushing x2

3. 1.5" tee

4. 1.5" male adapter (mpt?)

iron

1. 1.5x1" reducer (threaded)

misc

piston
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4" piston valved cannon-half done..( i spilt my cement...)

Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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Unread postAuthor: hi » Fri Apr 06, 2007 2:19 pm

i sure hope this helps you because it took me forever to draw and if this doesnt help, i dont know what will.

green=barrel black = piston, red= 1.5'' pipe. blue =tee, yellow= bushing/ reducer

http://img77.imageshack.us/img77/5443/pistontwohw4.gif

edit, yes thats right. I think you ment NPT though, there is no such thing as MPT that i know of. i wish you posted that sooner though.....

you fill it befind the piston by the way.
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Unread postAuthor: hi » Fri Apr 06, 2007 2:31 pm

wait, why in the hell would you need 2 bushings? is one for the chamber? and whats the male adapter for?
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Unread postAuthor: spudthug » Fri Apr 06, 2007 2:41 pm

thanks for are ur help hi i will be mentioning ur name in my post of the contest

edit: interchangebale barrels
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Unread postAuthor: spudthug » Fri Apr 06, 2007 7:08 pm

ok went to get all the parts i am going to machine yet another teflon piston to fit into 1.5" pipe and i am going to pretty much use his diagram....cost me another 45 effing dollars...damn copper
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Unread postAuthor: hi » Fri Apr 06, 2007 7:12 pm

test fit them before you solder, wouldn't want to have you go through the whole thing again.
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Unread postAuthor: schmanman » Fri Apr 06, 2007 8:19 pm

aren't copper fittings & pipe this big extremely expensive? where do you get them?

for 2" copper, it's like $95 for a 10 foot piece.
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Unread postAuthor: hi » Fri Apr 06, 2007 8:56 pm

somehow i doubt that he bought a 10 foot section. Small hardware stores, like mine, will cut the pipe to the size that you need.
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Unread postAuthor: spudthug » Sat Apr 07, 2007 5:00 pm

nope i bought ten feet....only 1 inch though...25 dollars...fittings were the thing that killed me....

im mad as hell i spent six hours with my dad at his shop working on this piston...then i am all done getting ready to go and i realize that no air will go through the piston into the chamber....how do i fixe this...if u need i will scan some pics...ill do that anyway but im gonna send this to u hi from private message incase u dont look at this psot because ur smart when it comes to pistons plus no one else will help me....


pics in original posts in 1 min
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4" piston valved cannon-half done..( i spilt my cement...)

Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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Unread postAuthor: Hawkeye » Sat Apr 07, 2007 7:17 pm

The air can go around the piston. Just make a very shallow groove or two along the side. Use a corner of a metal file. If it isn't a perfectly tight fit the air should leak past anyway.
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Unread postAuthor: spudthug » Sat Apr 07, 2007 9:15 pm

so hawk ur saying jsut make the grooves??? hi pmed me that but wont the psiton turn in there???if so the grooves would no longer be toward the chamber but maybe on the side or straight up will this matter??
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Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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Unread postAuthor: Hawkeye » Sat Apr 07, 2007 9:50 pm

Your pictures are a bit confusing. Does your barrel extend back to the center of the T? It almost looks like you are trying to make it seal the barrel and the chamber the way you have it set up.
If it seals the barrel it doesn't matter which side the air leaks past. Top, bottom, side, as long as it gets past it somehow.
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Unread postAuthor: spudthug » Sun Apr 08, 2007 5:33 pm

ok thanks hawk i got help from hi i dont have a camera here and i cant post it anyway because its my comp cannon but my air compressor is in my dads truck and he is in town...he will be back later and i will be shooting it....weeee!!!!!!!!! btw guys thanks for all the help whoever helped will be mentioned in the contest
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Hybrid- 75% done. need to build propane holder and drill/tap sparkplug hole..
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