One of the first non-wood building tasks that will present itself to RC modelers is “Drilling and Tapping” holes in metal parts. Mainly this is required for attaching your glow engine to you aluminum motor mounts, but the same process is used when drilling and tapping hardwood blocks for nylon wing hold-down bolts. Knowing the proper technique is key to making this task quick and easy, but the biggest rule not to break is to take nice and slow. if you rush you will break the tap inside the intended hole and that pretty much ruins the part and it will have to be replaced.
Tips for threading holes
1. Use the proper size bit to drill the hole. Most taps come in common sizes and are packaged with the proper size drill bit to drill the tap’s minor diameter, (the holes that will be threaded).
2. After drilling the hole, place the tap in a Tap holder tool and tighten into place. Apply a little oil in the hole and bear down a little bit on the tap. Keep the tap in line with the drilled hole, and while pressing downward, turn the tap about a full turn until you feel the cutting teeth grab into the material. When you feel the grab stop turning the tap.
3. Now back the tap out slightly (about a quarter turn), to “break” the chip that is formed in the hole as the threads are cut.
4. Repeat this process all the time keeping the tap aligned with the hole.
5. When the tap has fully threaded the hole, remove the tap and clean out any chips from the hole with a disposable acid brush.
Below are guides for the proper size drills for various size taps.