All the parts used in this instructable came from Lowes, except the compressor. The photos are tagged with the part number and price from lowes.
Gun in action:
Second version gun in action:
IMPORTANT: Skip to last step for a slightly more expensive, but better version.
Step 1: Get the Parts
The air compressor was from Sears, it's the Craftsman 1hp 3 gal. Air Compressor.
You can choose to build a 2 inch pipe model, or a larger one, either 3 or 4 inches. You'll only have to get a different size cap and pipe size.
Here's the list from Lowes:
- (Two of these) 1/4 to 1/4 Male coupler - $2.19 - #2270 (Their image is incorrect)
- 1/4 to 1/4 Female coupler - (Not sure of the price or where go get one, it came with my compressor)
- 2" PVC cap - $0.52 - #23406 (Not available online, easy to find elsewhere)
- 1/4 mini ball valve - $7.96 - #221029
- Pressure Gauge - $7.94 - #221022
- 7/16th drill bit - $7.58 - #219842 (Not available online, and you can find them anywhere, probably cheaper too)
- 1/4 NPT Tap - $9.97 - #232530
- 2"x5' PVC Pipe - $3.97 - #23833 (Not online, but easy to find)
- Compressor air adapter - Depends on what kind of compressor you have. (It'll most likely be a 1/4th NPT thread)
You'll also need an old, empty propane tank. If you don't have one, you can get an oxygen tank from Lowes for about $5. Thats the cheapest kind of tank you'll find.
For tools, you'll need a grinder (Or a hack saw), some vice grips (Or a tap wrench), a cordless drill with a clutch, a 5/16th ratchet socket thing, and some misc Allen wrenches.
Step 2: Burn Off the Propane
I just lit my torch, and left it underneath my porch, where we store fire wood. It's the only place that's outside, not covered in a foot of snow. Thank god nothing caught fire.
Do NOT do it inside, burning Propane lets off Carbon Monoxide, and burning out an entire tank, or even half a tank, could let off enough to kill.
If you use oxygen, I guess you can just let it out.
Step 3: Drill Your Hole
When you drill, I suggest first making a smaller hole, followed by the big 7/16th one.
Step 4: Tap Those Holes!
Step 5: Put in the Gauge and Inlet
Step 6: Modify the Ball Valve
Step 7: Create the Automatic Firing Mechanism
Now, check if that socket fits in your drill. If it does, you're all good. If not, you'll have to do what I did. Find an Allen wrench that fits into the opposite side of the socket, and make sure it doesn't spin when you put pressure on it. Do not try to over turn it, you'll strip the threads. I stripped mine, but all I had to do is take off the washer and use the threads there. Anyways, once you make sure it fits, you'll have to cut off the shorter half of the Allen wrench, so that it spins right. The first picture is the valve with the socket and wrench all set up. You can use a hack saw or a grinder, I choose grinder for this one, because it's less delicate. The long side of the allen wrench will go into your cordless drill, to fire. This is why you need a clutch drill, you have to put it all the way on 1, so it'll open the valve and start slipping when it hits the stop.
Step 8: Drill and Tap the Valve's Hole
When you're done, this hole will be hard as hell to tap. You'll need LOTS of wd40, i used half a can, and you'll need to do a reverse turn every 3 turns. I even managed to dull my tap on it. Oh well, gives me a good reason to return it, I guess.
Anyways, once you're done tapping, you should put some Teflon tape on, and screw in the valve. I had to grind the handle down a little, so it doesn't hit the tank on the way down.
Step 9: Pressure Test
Step 10: Modify the PVC Cap
Step 11: Glue the Cap Onto the Pipe
Step 12: Assemble Parts
I choose to duct tape a piece of wood to both the tank and the PVC for support, since that cap can't hold a lot.
I later found out that that cap, was a piece of crap. It broke on me.
This is what version 1.0 looked like, 2.0 is on the way.... with improved PVC pipe, and using only one drilled hole at the top of the cylinder.
Step 13: Version 2.0
One of my friends leaned against the air inlet, and caused it to break out of the threads. So that inspired me. This only has one hole drilled, in the top. It's way more reliable. There's about an inch of metal to tap, compared to a millimeter. The improved version is also portable too.
You'll need these additional parts:
- 1/4 npt female to female coupler
- 1/4 npt 3 way adapter (2 of them)
- Second ball valve
- And possibly a new tank.