ISO Metric Coarse Thread · DIN 13-1 / ISO 261
M56 Thread: Pitch, Tap Drill & Dimensions
M56 is an ISO metric coarse thread with a 5.5 mm pitch. The tap drill is 50.5 mm, and the internal minor diameter D1 is 50.046 mm.
| Nominal (major) diameter | 56 mm |
|---|---|
| Pitch | 5.5 mm (coarse) |
| Tap drill (D − P) | 50.5 mm |
| Pitch diameter d2 / D2 | 52.428 mm |
| Minor diameter, external d3 | 49.252 mm |
| Minor diameter, internal D1 | 50.046 mm |
| Thread depth, external h3 | 3.373 mm |
| Flank angle | 60° |
| Clearance hole (fine / medium / coarse) | 58 / 62 / 66 mm |
| Hex spanner size (ISO 4032) | 85 mm |
Common questions
What size drill do I use to tap M56?
Use a 50.5 mm drill. This is the standard tap drill for M56; for hard materials or deep threads a slightly larger drill reduces tapping torque.
What is the pitch of M56?
The pitch of M56 is 5.5 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.