Bit size

1, M3 and M5 are triangular thread codes, the pitch of M3 is 0.5, and the bit for drilling the bottom hole is φ 2.5. The pitch of M5 is 0.8, and the bit for drilling the bottom hole is φ 4.2.

2. The usual angle 120 is the included angle between two main blades, strictly speaking, it is 1 18.

3. Find the cutting speed when doing the process, and know the diameter of the drill.

4. Thread bottom hole:

M3 bottom hole is φ 2.5, M4 is φ 3.3, M5 is φ 4.2, M6 is φ 5, M8 is φ 6.7, M 10 is φ 8.5, M 12 is φ 10.2, and M 14 is φ.

The bottom hole of M 18 is φ 15.5, M20 is φ 17.5, M22 is φ 19.5, and M24 is φ 2 1.

The bottom hole of M27 is φ 24.