M42 Hex Bolts are manufactured to ISO 4014 / ISO 4017 with a coarse thread pitch of 4.5 mm. 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. In tight access a 6-point socket on the 65.0 mm flats gives the most engagement per degree of swing. Where the joint is torqued to a figure, a click wrench is the only way to reproduce it across a batch.
Hole Sizes for M42
| Coarse-thread pitch (ISO 724) | 4.5 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 45 mm |
| Tapping drill, coarse thread | 37.5 mm |
Tightening Torque for M42
| Class 8.8 (dry, ~µ 0.125) | ≈ Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ Nm |
Indicative dry-joint values. Lubrication can lower the required torque by 15–25%. Always confirm against the joint design, especially when going up a strength class.
Proof Load & Strength for M42
| Tensile stress area As (ISO 724) | 1121 mm² |
|---|
Proof load = tensile stress area × the proof stress Sp of the class, per ISO 898-1 — Sp is a lower figure than the yield stress Rp0.2 and the two are not interchangeable. The stress area is computed from this size's own diameter and pitch, so a fine-pitch designation gives the fine-pitch figure. Design the joint so the working preload stays below the proof load of the class selected.
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.
- Serrated flanges need to sit directly on the joint face. A washer between the two removes the bite and leaves an ordinary bolted joint that is believed to be a locking one.
- 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.
Custom manufacturing · Made to drawing
Need hex bolts in a size this table does not list?
This page covers M42 hex bolts. Where the standard stops, the drawing takes over: fine pitches, left-hand threads, partial threading, and property classes above the catalogued grade where material and heat treatment allow. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
