M2.5 Socket Head Cap Screws
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About M2.5 Socket Head Cap Screws
M2.5 socket head cap screws to ISO 4762 / DIN 912, in stainless steel 304. The cylindrical head takes an internal hex, which is why this is the size you reach for when the joint needs real torque or the head has to sit down a counterbore.
M2.5 in numbers
| Thread | M2.5 × 0.45 mm coarse |
| Tap drill, 75% engagement | 2.05 mm |
| Clearance hole, ISO 273 medium | 2.9 mm |
| Hex key | 2.0 mm |
| Head diameter | 4.5 mm |
| Head height | 2.5 mm |
The counterbore has to clear 4.5 mm across and 2.5 mm deep for the head to finish flush. Drill the pilot at 2.05 mm for a tapped hole, 2.9 mm for a through hole.
Why this head
The hex socket engages six flats instead of a cross recess, so it takes far more torque before anything rounds out, and a ball-end key reaches it at an angle. Against that: the socket fills with debris, and a worn key will round it. Seat the key fully before loading.
Material
Stainless steel 304 — non-magnetic annealed, good atmospheric corrosion resistance, not rated for prolonged salt water. Stainless against stainless galls, so run it down slowly and skip the impact driver.
Every listing gives the full dimensions in millimetres and inches, plus the nearest imperial thread with a note on why it is not interchangeable.