I began searching the internets for tips, instructions and what not. A week ago i decided i knew enough to make a simple combustion-style one, so i bought some PVC pipe and fittings.
(Pic will go here once i gets the camera back)
I read that a fan in the chamber would increase the performance about 25-30%, so i found a 90mm brushless computer fan which i appropriated for my needs using a dremel
After that, I started thinking about ignition. There are many ways to do this, ranging from poking a match or a lighter through a hole in the chamber (If you do this you deserve it) to using multiple flyback transformers to create sparks everywhere in the chamber.
I settled after some thinking for a BBQ igniter (pushbutton piezo thingeh). As a side note, no general stores seem to carry disposable cameras any more :/
After searching stores around where i live and the internet for a few days, i just looted one from my our propane grill (We never used it anyway meh)
Now for somewhere to create the spark inside the chamber. I made a ghetto spark strip out of two washers and a penny for this purpose.
(pic goes here when i gets the camera back)
With both the fan and the ignition done, I started on joining my parts together. Most spudders use PVC cement for their assembly, but seeing as no plumbing-supply stores seem to carry that either, i used plastic cement and screws instead (and i really hope this holds)
After letting hte cement dry overnight I started drilling holes for screws and putting the fan and ignition in there.
Now it was time for putting the whole thing together
After an anxious nights waiting while the cement set, I was finally able to try it out.
I stuffed a plug of newspaper into the barrel (just to hold the gases in the chamber), sprayed some deodorant in there and closed 'er up.
Now to stand back a bit, push the button and watch the boomshine.
Click... Click.. Clickclickclickclick
It appears that the spark strip for some reason shorted out and didn't give me a spark .(
As i couldn't get it out (it was wedged in by the fan), I had to make a new one which was thinner and poke it in there.
A two minute hackjob which produced a single, but consistent spark.
After installing my new spark gap, i primed 'er up again.
This time however, the click was instantly followed by a loud bang which left my ears ringing. I cackled like a maniac; MY GUN WORKS!
(the poor newspaper plug got it the bad way .( )
After firing a few more blanks with newspaper plugs, I went inside and got me a tater. I loaded it and primed up the gun.
Stepping back, i pushed the button.
BANG. The recoil rocked the mount and knocked all the stuff off it.
It appeared that the mount wasnt the only thing that got knocked off.
I knocked a board clean out of the wall, taking the eight nails with it and vaporising the poor 'tato in the process
(these were the only parts of the valiant potato i could find, apart from a thin white film of starch)
Im going to field test it tomorrow if the weather and all permits. Hopefully i will have an estimate of muzzle velocity, energy and range by then.
you could go 4x MAPP if you have decent fittings (and some cover just in case)
