Thread Tapping Tutorial

First off, the tools.

[color=Red][b]Required:[/b][/color] A thread tap (and the drill bit that comes with one). These come in many different thread pitches. Ultra uses 8-32 threading for his blade retention screws. If you strip out that screw, go to 10-32 thread pitch.

This is a picture of a tap and the drill bit it uses.

Some kind of power drill. A drill press is HIGHLY RECOMMENDED, because with hand drill, you risk the bit wandering.

[color=Red][b]Optional, but HIGHLY recommended:[/b][/color] Tap handle. The tap handle holds the tap, like the chuck on a drill holds the bit. The handle allows you to keep the tap at 90 degrees, and gives you plenty of torque. You can tap without the handle, by using pliers to hold the tap. This isn't recommended though, and come on, the handle is all of 6 bucks. DO NOT USE A DRILL PRESS FOR THE TAPPING. YOU WILL DESTROY YOUR TAP.

[color=Red][b]The Idiot Proof Steps To Tapping[/b][/color]

1) Secure the drill bit that comes into your drill. A drill press is HIGHLY recommended.

2) Secure the work piece. A drill press vice is HIGHLY recommended.

3) Drill the hole. Make sure you drill at the peak of the hilt's curve, otherwise, you will have a crooked hole.


4) Clean out the hole, make sure that no metal scraps are still in the hole.
5) Attach the tap to tap handle. DO NOT USE DRILL PRESS INSTEAD OF A TAP HANDLE. YOU WILL DESTROY YOUR TAP AND HOLE.
6) Begin tapping the hole. You want to turn the tap handle 1/4 to 1/2 a rotation, and then back it out to remove material. Using lubrication during this step is highly recommended. DO NOT just tap the entire hole without backing out the tap. You run the risk of breaking that tap, and even if you don't, you will have a very poorly threaded hole.

7) Run the tap through the hole one last time, just to make sure it is threaded well. Clean out any metal shavings still in the hole. A can of compressed air works well here.

8 ) Thread your screw into the hole. Make sure you have the same thread pitch screw as hole. Otherwise, it won't work.
9) Enjoy your beautifully threaded hole

Here is a good drill bit-tap reference chart.

8-32 is M4x0.7.
6-32 is M3.5 x .06.
10-32 (I'm assuming that's "UNF") is M5 x .08.
4-40 is M3 x .05.

Here is a complete chart. Credit goes to Wikipedia.

Another formula is: to find the right size drill bit for the tap subtract the thread pitch from the screw size. Example: M5 screw with a .7 thread pitch would require a 4.3 drill bit.