M8 Slotted Headless Screws with Shank (ISO 2342) are specified by thread size, length and head dimensions. The M8 row from the standard is reproduced below, followed by the drill sizes, spanner size and torque values used when installing this size.
M8 Dimensional Row (ISO 2342)
| Size | Pitch P (mm) | b (mm) | d_s_min (mm) | d_s_max (mm) | n_nom (mm) | n_min (mm) | n_max (mm) | t_min (mm) | t_max (mm) | x_max (mm) | Length range l (mm) | Reference standard |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| M8 | 1.25 | 9.6 | 7.78 | 8 | 1.2 | 1.26 | 1.51 | 3.1 | 3.6 | 3.2 | 14~30 | ISO 2342 |
Spanner & Drive for M8 Slotted Headless Screws with Shank
The hex socket for M8 Slotted Headless Screws with Shank is shown in the spec table — use the matching Allen / hex key (an ISO 2936 hex key set covers the full range). For a one-off, a T-handle key and a calibrated arm will do. For a batch, the only way to get the same preload twice is a torque-controlled driver.
Hole Sizes for M8
| Coarse-thread pitch (ISO 724) | 1.25 mm |
|---|---|
| Through-hole / clearance (ISO 273 medium) | 9 mm |
| Tapping drill, coarse thread | 6.75 mm |
Tightening Torque for M8
| Class 8.8 (dry, ~µ 0.125) | ≈ 24 Nm |
|---|---|
| Class 10.9 (dry, ~µ 0.125) | ≈ 36 Nm |
| Class 12.9 (dry, ~µ 0.125) | ≈ 42 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 M8
Set screws are rated to ISO 898-5 by hardness, because they work in compression against a shaft rather than in tension. ISO 898-1 excludes them, and a set screw has no head to preload against, so neither a property class nor a preload torque applies. Seating torque depends on the point form and the shaft material.
M8 Slotted Headless Screws with Shank Weight
A steel M8 slotted headless screws with shank at the listed 1,430 mm length weighs approximately 564 g each — about 564 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.
Mating Parts for M8
For M8, pair with a M8 hex nut (ISO 4032 / DIN 934) and, where used, a M8 flat washer (ISO 7089 / DIN 125A) under the head and under the nut.
When to Step Up or Down from M8
When the joint preload approaches the proof load of M8 class 8.8, step up to M10 class 8.8 (or move to M8 class 10.9). When the joint is over-specified, M6 often saves weight and cost without losing the safety margin.
Custom manufacturing · Made to drawing
Need slotted headless screws with shank in a size this table does not list?
This page covers M8 slotted headless screws with shank. Material and finish are usually what drives a special — a grade the standard part is not stocked in, or a coating chosen against a salt-spray figure instead of a default. Made by cold heading or warm forging.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
