ISO Metric Coarse Thread · DIN 13-1 / ISO 261
M39 Thread: Pitch, Tap Drill & Dimensions
M39 is an ISO metric coarse thread with a 4 mm pitch. The tap drill is 35 mm, and the internal minor diameter D1 is 34.67 mm.
| Nominal (major) diameter | 39 mm |
|---|---|
| Pitch | 4 mm (coarse) |
| Tap drill (D − P) | 35 mm |
| Pitch diameter d2 / D2 | 36.402 mm |
| Minor diameter, external d3 | 34.093 mm |
| Minor diameter, internal D1 | 34.67 mm |
| Thread depth, external h3 | 2.453 mm |
| Flank angle | 60° |
| Clearance hole (fine / medium / coarse) | 40 / 42 / 45 mm |
| Hex spanner size (ISO 4032) | 60 mm |
| Socket cap screw hex key (ISO 4762) | 27 mm |
Common questions
What size drill do I use to tap M39?
Use a 35 mm drill. This is the standard tap drill for M39; for hard materials or deep threads a slightly larger drill reduces tapping torque.
What is the pitch of M39?
The pitch of M39 is 4 mm (coarse), meaning the thread advances that distance in one full turn.
Where can I find other ISO Metric Coarse Thread sizes?
The full ISO Metric Coarse Thread table, with every size and a live filter, is on its standard page, and the Thread Finder searches all 73 standards at once.
Reference values; computed values use the ISO basic profile. Verify against the current standard before production use.