Monster V1 - GB Adv Comb

[JET47]

Just finished my first combustion gun tonight. Haven't fired it yet though, don't want to wake up the neighbors =P but damage pics coming eventually.

Advanced combustion, it's got a chamber fan wired to a switch on the handle, and a piezoelectric sparker wired to multiple spark gaps for ignition. it's epoxied into the handle, which is made of wood. approx C:B ratio is 0.6-1.0

The cannon is breech-loaded, with a modified ball valve. theres a diagram of the gun here. threw a short piece of SCH40 1.5" pvc into the valve and tapered it down, so it catches and holds the ball from sliding out the barrel.

The meter it tapped into the chamber. I was a little confused- i got my hands on a whole tap set and the 1/4" NPT tap was not anywhere near big enough for the 1/4" brass piping i bought at home depot. figured out through trial and error on scrap that the 1/2 tap was the right size i needed, weird.

And as an added bonus the cannon is made to be comfortably hand-held. Hooray, portable destruction.[/url]

[King_TaTer]

Wow, thats a very interesting gun man. Even though it is quite unattractive I find myself somewhat excited about it.

For one, the use of a ball valve as a breech is something I have never seen before and is quite remarkable. I mean that idea has never occurred to me, thats awsome man.

Also, your metering system is different as well. I wonder why you used 2 pressure gauges, if you could explain that please. A different way of metering perhaps?

Your C:B ratio is also very good, and I'm glad you took the time to incorporate that into your cannon considering this is your first advanced combustion. It wouldn't hurt if you did shave a few inches off the end of your barrel, though its not of great importance.

I have never been a big fan of those "shortie" propane cylinders used for camping, even though they may be lighter and more compact. They just seem ugly to me, oh well.

Oh and one last thing, are those 2 film canisters strapped on to the back? Well whatever they are, what are they for?

Overall I give you an 8 out of 10 mostly for originality and ingenuity. Oh, and good luck shooting it tomorrow. 8)

[starman]

OK that thing has turned out fairly well, assuming it actually fires of course. I like the stubby fat rifle look and pistol grip...chamber and barrel are proportioned well. Breech loader is awesome...

However....

Your meter and taped-on propane tank mounting seems like a bad after thought. Your drawing from before didn't look so bad, but this, I'm sorry to say, looks thrown together and without hope. Even hose clamping the tank, I'm not sure would help...just kind-of gangly looking.

Let us know when you shoot it. Give your tank and meter setup some more thought.

[JET47]

heh, ya ive gotta admit the tape was due to eagerness to finish it, should've waited for more hose clamps.

film canisters hold the batteries for the fans.

one of the pressure gauges is part of the regulator, and the other is on the meter chamber itself, so say when its full? im not sure, i based my meter design off the wiki

and when i was planning it i had wanted to paint it all black, i might still do that.

[SpudFarm]

replace the ball valve with a sprinkler

[mark.f]

Looks good, same questions as everybody else. What are the film canisters for?

[JET47]

they hold the batteries for the fan.

[starman]

replace the ball valve with a sprinkler

Deeerrr uhmmm, how pray-tell, do you arrive at that advice?...for this combustion gun...

[uncomplientspud]

like the breech loading, very cool idea

[spencetron]

Did you end up putting the SDR21 inside the ball valve like in your original design?

[rp181]

Spudfarm, the ball valave is just for breach loading. The back valve is for venting.

I must say, strange design, but good overall.

[JET47]

yes, the inside of the ball valve is sleeved with SDR21, and the deepest part is done with a little piece of sch40 that i tapered down with a dremel. so when i put in the golfball itll catch and stick in the breech and not roll out the front.

I still havn't got the thing to fire yet though =/ its kindve on hold for the moment, taken the backseat to my next project, a brass pneumatic penny roll sniper rifle, fun fun

[Mr.Sandman]

nice cannon. i dont think ive even made an advanced combustion. perhaps i will when i get some money 8) how did you make the handle?
i mean, I know its wood but did you hand shape it or did you use a band saw? also an upgrade you could do is get an electronic grill starter that way you dont have tokeep clicking down on the igniter because electric ones make multiple sparks if you hold down the button

[JET47]

handle was traced from another gun onto a 2x4, cut out with a jigsaw, and shaped with a dremel. just held it to feel where it needed to be smoothed down. haha i was using a big file it first it took forever.

[Mr.Sandman]

you should paint it.not that you HAVE to,but i think it would be peretty sweet if you did. any ways whan you fire post a new thread cause i really want to know how far it goes (of course i could ggdt it but sometimes it is off so id rather hear what really happens)