Water Bottle Bazooka

Step 5 Hollow out the Threaded Coupler

The threaded coupler will eventually slide into the end of the reduction coupler, and provides something for the cork to push against. The hole in the threaded coupler allows a bike pump nozzle to be connected.

In order for everything to fit together, most of the threaded section must be removed. Unfortunately, it's recessed inside the coupler making it impossible to cut out with a saw. Instead, I used a drill press to cut out the threaded section.

Using a drill press it's easy to set the depth gauge so that you don't end up drilling all the way through the end of the coupler. Set the gauge so that the drill bit will stop at the same level as the inside edge of the coupler. Drill down though the thickness of the threaded section with a 1/2" drill bit, working your way all the way around. Clean up any plastic cuttings.

Now, you can go back and use the drill press as a sort of milling machine (of course, if you have a milling machine, use that!). Plunge the bit all the way down to the stop, and pass it over the drilled out parts to eliminate any peaks that remain. Do this until the inside of the coupler is relatively flat.

Comments

[Nicholai]

i saw the threads and wondered if i could put an air compressor line on it with a check valve(in place of the presta valve) and pressure monitor guage (for safety) to make it quicker/easier to charge.  do you think i could do this safely? 

[jeff-o]

Sure, that would probably work.  It would be no less safe than a bike pump, as long as you limit the pressure of the air compressor.