MAPC-50

Boom! The classic potato gun harnesses the combustion of flammable vapor. Show us your combustion spud gun and discuss fuels, ratios, safety, ignition systems, tools, and more.
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schmanman
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Wed Nov 22, 2006 6:45 pm

wow, that ghetto award... gort, you have a little too much time on your hands!

how long did it take to to make that? I like the special primer application. :lol:
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Thu Nov 23, 2006 11:42 pm

I see you Homies know your stuff... but did you know this?

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Killjoy
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Mon Nov 27, 2006 9:14 pm

yeah that awrad is pretty funny...thanks a lot lol.
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mark.f
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Sat Dec 02, 2006 11:23 am

I hope you don't mind, but I am going to "steal" this idea, except I'm gonna use the 3" fitting attachment method on both ends of the chamber. Just giving you a heads-up, (I would call this asking permission, but I just ordered a bunch of stuff off McMaster-Carr to build it 8) ), before I try it. How much "blowtorching" does it take to fit an end of the 2 liter over the 3" fittings and how much does it warp the plastic?

If this seems like it won't work for me, I'll just get some clear 4" pipe from Gort or somebody to replace the 2-liter over the 3" fittings. But I really like the idea of the 2-liter as a chamber. Might double-wall it if it seems too thin, though.
Killjoy
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Sun Dec 03, 2006 12:50 am

sure bro go ahead, thats why i put the cannon on this site to give people ideas. It doesnt take much blowtoraching. cause the 3"cap is only a little bit smaller then the bottle, just a couple passes by the blowtorch should do it. Youll know when the bottles on tight (if the plastic starts to turn brown and smolder, then you know youve heated it to long) try to leave like 1"icnh or 1 1/2" of bottle thats going to be shrunk on to the cap.
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jjjd
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Sun Dec 03, 2006 10:59 am

Ghetto! love the gun, and the gheto award
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mark.f
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Sun Dec 03, 2006 1:44 pm

Allright. I just tried this with some old 3" fittings I had lying around, and I didn't really like the way the plastic could collapse and dent and everything. I'm just gonna sleeve some 4" over the 3" fittings I've got already.
Killjoy
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Sun Dec 03, 2006 11:06 pm

alright cool, hope everything turns out good.
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zeigs spud
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Sun Jan 07, 2007 7:46 pm

holy...god thats nice lol. but barrel looks a bit to large. still...it's a kick a$$ lookin cannon
pyromanic13
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Sun Jan 07, 2007 7:57 pm

does the gun expand when you shoot it?
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iknowmy3tables
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Sun Jan 07, 2007 8:19 pm

sort of he said the dents pop out and he lets it cool
Killjoy
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Mon Jan 08, 2007 1:04 am

yeah it usually does expand a little, but the other day when i was fireing it, i tried weighting a spud with lead (don't ask), and the potato didn't exit the barrel, so the hot gases escaped out the little hole for the fan wires and the bottle colapsed (cause of the rapid decrease in pressure and the bottle being hot). I was able to get it to "pop" to its orignal size with some compressed air though afterwards. The entire event was pretty interesting.
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zeigs spud
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Tue Jan 09, 2007 9:21 pm

well that obviously weakend the bottle i say this is a good chance for you to put pvc in instead of a thin plastic bottle.

but where did u get that ignition box thing and how much did it cost?
Killjoy
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Wed Jan 10, 2007 12:36 am

nah, i pressure tested the cannon again cause i wasn't sure about the bottle and it held 130 psi with no problem for about an hour (finnaly sealed the hole for the wires to the fan). and anyways the bottle is what makes this gun ghetto and unique.
the ignition box is something i made. like i said i used a camera igniton setup (which i put a how to on this site also), i got the switch with the safety cover, and fan switch from radio shack as well as a project box, and then just mounted evry thing inside, drilled a couple holes for the wire which i put vinyl grommets (or what ever, ther'ye from radio shcack) in the holes and pushed the wires though to the other side. not necesary but i thought it looked better. the enitre thing cost me like 20 bucks.
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zeigs spud
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Thu Jan 11, 2007 10:30 pm

for the camera ignition the wiresmust touch for a spark. how did u make that possible by pushin a button?
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