M42 Hex Head Cap Screws, Fully Threaded, Grade C are manufactured to ISO 4018 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 4018)
| Size | Pitch P (mm) | a_max (mm) | a_min (mm) | c_max (mm) | d_a_max (mm) | d_w_min (mm) | Width across corners e (mm) | Head height k (mm) | k_max (mm) | k_min (mm) | k_w_min (mm) | r_min (mm) | Width across flats s (mm) | s_min (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M42 | 4.5 | 13.5 | 4.5 | 1 | 48.6 | 59.95 | 71.3 | 26 | 27.05 | 24.95 | 17.47 | 1.2 | 65 | 63.1 | 80~420 | ISO 4018 |
Spanner & Drive for M42 Hex Head Cap Screws, Fully Threaded, Grade C
M42 Hex Head Cap Screws, Fully Threaded, Grade C have a width across flats of 65 mm — fit a 65 mm open-ended spanner or socket. A 6-point socket grips all six flats of the 65 mm hex and is what to reach for once a fastener has been on and off a few times; a 12-point ring spanner starts rounding a worn head. For repeatable preload, torque rather than feel.
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.
M42 Hex Head Cap Screws, Fully Threaded, Grade C Weight
A steel M42 hex head cap screws, fully threaded, grade c at the listed 80,420 mm length weighs approximately 875,372 g each — about 875,372 kg per 1,000 pieces. Stainless A2/A4 weighs roughly the same (density 7.9–8.0 g/cm³).
Actual weight varies slightly with head form, thread and finish; use this figure for freight estimation only.
Installation Tips for M42 Hex Head Cap Screws, Fully Threaded, Grade C
- 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.
Custom manufacturing · Made to drawing
Need hex head cap screws, fully threaded, grade c in a size this table does not list?
This page covers M42 hex head cap screws, fully threaded, grade c. Thread size and pitch, length, property class, drive form, head geometry and head marking are all specifiable — the standard part is where it starts, not where it stops. Made by cold heading or hot forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
