Warning: Wear safety glasses when using tools.
Warning: Use oven mitts when using the injector.
Step 1: Center End Caps
If you have a lathe, all you'll want to do is to insert a 3/4" non-galvanized nipple into the lathe, put on a cap, and drill the hole. I don't have a lathe since they cost more than I'm willing to pay, so I create an adapter for use with my drill press. Here are the steps:
- Find the biggest dowel that your drill press will accept.
- Cut a short piece of the dowel off.
- Wrap the dowel in masking tape so that it'll fit tightly into a 3/4" nipple.
- Insert the dowel into the drill press / hand drill.
- Insert the smallest 3/4" nipple you can, on top of the dowel adapter.
- Screw a cap onto the nipple-adapter.
- Place knife / blade onto cap while spinning.
With respect to step #7, the rotation tends to push the cutting blade towards the center of rotation. If this doesn't happen, you may need to (roughly) level the cap-tops and try again. A fresh blade from a utility knife works great, though I used some sewing scissors.