M24 x 3 tap drill size
21 mm
- Inches
- 0.8268
- Inch bit
- 53/64"
- Thread
- 77%
Drill a 21 mm hole before cutting an M24 thread with 3 mm pitch. The rule for metric taps is diameter minus pitch.
No metric bits? A 53/64" bit (0.8281 in) gives about 76% thread.
M24 x 3 thread and hole sizes
| Thread | M24, 3 mm pitch, coarse |
|---|---|
| Major diameter | 24 mm 0.9449 in |
| Tap drill | 21 mm 0.8268 in |
| Closest inch bit | 53/64" 0.8281 in |
| Clearance hole, close fit | 25 mm |
| Clearance hole, medium fit | 26 mm |
Why 21 mm
Subtract the pitch from the diameter: 24 minus 3 is 21 mm. That leaves 77% thread, the usual target for a cut tap.
More thread than that adds almost no strength and makes the tap much easier to break. In hard or tough material, go 0.1 mm larger.
Tools for this job
- M24 x 3 tap
- 21 mm drill bit
- Tap and drill set
- Drill bit size gauge
- Thread pitch gauge
- Cutting oil for tapping
As an Amazon Associate we earn from qualifying purchases. Details