M42 Hex Bolts are manufactured to ISO 4014 / ISO 4017 with a coarse thread pitch of the standard value. This page lists the controlling dimensions for the M42 size — head geometry, width across flats, matching spanner size — together with the clearance hole, tapping drill and tightening torque used at assembly.
M42 Dimensional Row (ISO 4014 / ISO 4017)
| Size | Pitch coarse (mm) | Width across flats s (mm) | Width across corners e min (mm) | Head height k nom (mm) | Nominal diameter d (mm) | Reference standard | Notes |
|---|---|---|---|---|---|---|---|
| M42 | 4.5 | 65.0 | 71.3 | 26.0 | 42.0 | ISO 4014/4017 | Partial / fully threaded |
Spanner & Drive for M42 Hex Bolts
M42 Hex Bolts have a width across flats of 65.0 mm — fit a 65.0 mm open-ended spanner or socket. Use a 6-point socket for tight clearances and to reduce rounding; for repeated assembly choose a torque wrench so the joint preload is repeatable.
Common Applications for M42 Hex Bolts
M42 Hex Bolts are commonly specified for structural steelwork, heavy machinery foundations and large flange joints.
Installation Tips for M42 Hex Bolts
- Use a 6-point socket where access allows — 12-point sockets are more prone to rounding the corners on smaller sizes.
- On flanged or serrated variants, do NOT add a separate flat washer — the flange already spreads the load and the washer can defeat the locking serrations.
- At M42 the stretch in the bolt becomes the controlling factor — for critical joints, use angle-controlled or stretch-controlled tightening instead of pure torque.
Mating Parts for M42
For M42, pair with a M42 hex nut (ISO 4032 / DIN 934) and, where used, a M42 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
