- A sharp utility knife
A black marker (not permanent, just for ink transfer marking)
Sandpaper (medium grit)
A mitre box (if available)
A ruler or set of calipers (accuracy not too crucial)
- Two or more coke bottles (they're trash, don't complain) with caps
A scrap length of 1/2" SCH-40 PVC pipe (pressure rated)
A 3/4" x 1/2" SCH-40 spigot x slip PVC bushing
A 3/4" SCH-40 PVC male adapter (slip x mnpt)
Like I said, this is just to make the overall connection look better. It's not exactly a revolutionary process. Some might be familiar with it, even.
To start, cut off the neck of a coke bottle with the utility knife. This isn't going to be the one to be attached to the gun/pipe, so don't waste too much time. Apply black ink (from the marker) to the end (as flush as possible!) of the scrap length of pipe. With the cap on the bottle-neck, push the pipe in from the back until it presses against the inside of the cap and leaves the ink.
Take this cap off, and discard the bottle-neck. Use the utility knife to cut out a hole the same size as the outside diameter of the 1/2" pipe (imprinted in ink). If you have one, a small gasket cutter can do this as well.
Attach the cap with the hole in it to the bottle you intend to use for the chamber. Screw it on as tight as you can. Push the pipe into the cap and bottle neck so that the bottom is flush with the bottom of the cap (out of sight). Mark this point on the pipe with a pencil.
Take a look at your bushing. It should have either a hex or round lip on the end, which will wind up (usually) flush with the fitting it goes in. Measure the length of this portion, and mark that length with pencil from the BACK of the bushing. Use a hacksaw to trim off the back of the bushing at the mark, and then use a file and sandpaper to reduce the "rim" at the front to the same outside diameter as the rest of the bushing.
Ensure that the bushing fits flush into the male adapter.
Measure the socket depth of the bushing. Subtract about 1/32" off that measurement, and mark this measurement past the mark you have already made on the pipe. Cut the pipe here, and remove any burrs.
Roughen up the inside of the bottleneck and the lower portion of the 1/2" pipe (that you measured first) with sandpaper. Clean with soap and water, and you're ready to roll.
Mix your epoxy, and apply to the inside of the bottleneck and the outside of the pipe. Push the pipe into the bottleneck until it is against flush with the bottom of the cap (or lined up with the mark you made earlier), and twist to remove any air pockets. Wipe off any excess epoxy (you can use acetone to get the surfaces really clean), and allow the epoxy to set up. This time will be marked on your epoxy tubes.
After the epoxy has set up, solvent weld the bushing onto the length of protruding 1/2" pipe. Allow this to set up for about five minutes, and then solvent weld the bushing into the 3/4" male adapter. Of course, if you have clear primer, that would be nice, but if you're using purple primer, make sure to tape off all exposed surfaces and wipe off excess cement and primer after each joint is done.
Voila! That is it. Let the entire assembly cure for 24 hours or the marked cure time on the epoxy tubes (whichever is longest), and it will be ready to use. Simply screw the 3/4" male adapter into the rest of your gun.
Additionally, some small screws can be tapped and sealed with rubber washers or more epoxy through the bottleneck and 1/2" pipe, for an extra safety factor, but as long as you take the time to prepare the surfaces beforehand, and mix the epoxy correctly (syringes suggested), then you should be perfectly fine without these screws.
Below is a picture of the final product. I am planning on making a gun like this next paycheck, and will have an updated full tutorial by then. For now, a crude drawing will have to work, along with the (I think) comprehensive instructions detailed above.
The good thing about this design is it is sooo picky. You can scale it down as much as you want, and compromise as much as you want as far as aesthetics, and the general idea still works.