# Countersunk socket screws, M2–M8 (ISO 10642 / DIN 7991)

> What countersink does an M3 flat head screw need?

- Category: Hardware › Fasteners
- Kind: Hardware
- Basis: ISO 10642 / DIN 7991 (actual head diameter, 90° countersink)
- Page: https://xemstudio.com/objects/countersunk-screws-metric/ · JSON: https://xemstudio.com/api/geometry?object=countersunk-screws-metric · Plain text: https://xemstudio.com/objects/countersunk-screws-metric/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

## Notes

- Head sits flush in a 90° countersink. Countersink diameter = head diameter + 0.3 mm; depth = head height. In a print, add 0.2 mm to the diameter.
- Head height is about 0.55 × thread. Minimum material under the head on a printed part: 1.5 mm or it pulls through.

## Sizes

| thread | head_dia_mm | head_height_mm | hex_key_mm | csk_dia_in_print_mm |
|---|---|---|---|---|
| M2 | 4.4 | 1.2 | 1.3 | 4.9 |
| M2.5 | 5.5 | 1.5 | 1.5 | 6.0 |
| M3 | 6.0 | 1.7 | 2.0 | 6.5 |
| M4 | 8.0 | 2.3 | 2.5 | 8.5 |
| M5 | 10.0 | 2.8 | 3.0 | 10.5 |
| M6 | 12.0 | 3.3 | 4.0 | 12.5 |
| M8 | 16.0 | 4.4 | 5.0 | 16.5 |

## Where the files are

- McMaster-Carr: [Socket head screws (free STEP/IGES/STL per part, for your own design use; no redistribution)](https://www.mcmaster.com/products/socket-head-screws/) — STEP, IGES, STL, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)
- Wikipedia: [Screw](https://en.wikipedia.org/wiki/Screw) — web — CC BY-SA 4.0 (text)

## Free STEP/STL (35 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/countersunk-screws-metric/index.json

- csk-m2x4: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2x4.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2x4.stl) — ISO 10642 M2 × 4, 90° head, thread as plain cylinder
- csk-m2x6: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2x6.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2x6.stl) — ISO 10642 M2 × 6, 90° head, thread as plain cylinder
- csk-m2x8: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2x8.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2x8.stl) — ISO 10642 M2 × 8, 90° head, thread as plain cylinder
- csk-m2x10: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2x10.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2x10.stl) — ISO 10642 M2 × 10, 90° head, thread as plain cylinder
- csk-m2.5x6: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2.5x6.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2.5x6.stl) — ISO 10642 M2.5 × 6, 90° head, thread as plain cylinder
- csk-m2.5x8: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2.5x8.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2.5x8.stl) — ISO 10642 M2.5 × 8, 90° head, thread as plain cylinder
- csk-m2.5x10: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2.5x10.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2.5x10.stl) — ISO 10642 M2.5 × 10, 90° head, thread as plain cylinder
- csk-m2.5x12: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2.5x12.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m2.5x12.stl) — ISO 10642 M2.5 × 12, 90° head, thread as plain cylinder
- csk-m3x6: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x6.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x6.stl) — ISO 10642 M3 × 6, 90° head, thread as plain cylinder
- csk-m3x8: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x8.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x8.stl) — ISO 10642 M3 × 8, 90° head, thread as plain cylinder
- csk-m3x10: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x10.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x10.stl) — ISO 10642 M3 × 10, 90° head, thread as plain cylinder
- csk-m3x12: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x12.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x12.stl) — ISO 10642 M3 × 12, 90° head, thread as plain cylinder
- csk-m3x16: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x16.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x16.stl) — ISO 10642 M3 × 16, 90° head, thread as plain cylinder
- csk-m3x20: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x20.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m3x20.stl) — ISO 10642 M3 × 20, 90° head, thread as plain cylinder
- csk-m4x8: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x8.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x8.stl) — ISO 10642 M4 × 8, 90° head, thread as plain cylinder
- csk-m4x10: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x10.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x10.stl) — ISO 10642 M4 × 10, 90° head, thread as plain cylinder
- csk-m4x12: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x12.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x12.stl) — ISO 10642 M4 × 12, 90° head, thread as plain cylinder
- csk-m4x16: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x16.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x16.stl) — ISO 10642 M4 × 16, 90° head, thread as plain cylinder
- csk-m4x20: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x20.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x20.stl) — ISO 10642 M4 × 20, 90° head, thread as plain cylinder
- csk-m4x25: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x25.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m4x25.stl) — ISO 10642 M4 × 25, 90° head, thread as plain cylinder
- csk-m5x10: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x10.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x10.stl) — ISO 10642 M5 × 10, 90° head, thread as plain cylinder
- csk-m5x12: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x12.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x12.stl) — ISO 10642 M5 × 12, 90° head, thread as plain cylinder
- csk-m5x16: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x16.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x16.stl) — ISO 10642 M5 × 16, 90° head, thread as plain cylinder
- csk-m5x20: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x20.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x20.stl) — ISO 10642 M5 × 20, 90° head, thread as plain cylinder
- csk-m5x25: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x25.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m5x25.stl) — ISO 10642 M5 × 25, 90° head, thread as plain cylinder
- csk-m6x12: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x12.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x12.stl) — ISO 10642 M6 × 12, 90° head, thread as plain cylinder
- csk-m6x16: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x16.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x16.stl) — ISO 10642 M6 × 16, 90° head, thread as plain cylinder
- csk-m6x20: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x20.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x20.stl) — ISO 10642 M6 × 20, 90° head, thread as plain cylinder
- csk-m6x25: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x25.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x25.stl) — ISO 10642 M6 × 25, 90° head, thread as plain cylinder
- csk-m6x30: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x30.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m6x30.stl) — ISO 10642 M6 × 30, 90° head, thread as plain cylinder
- csk-m8x16: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x16.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x16.stl) — ISO 10642 M8 × 16, 90° head, thread as plain cylinder
- csk-m8x20: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x20.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x20.stl) — ISO 10642 M8 × 20, 90° head, thread as plain cylinder
- csk-m8x25: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x25.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x25.stl) — ISO 10642 M8 × 25, 90° head, thread as plain cylinder
- csk-m8x30: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x30.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x30.stl) — ISO 10642 M8 × 30, 90° head, thread as plain cylinder
- csk-m8x40: [STEP](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x40.step) · [STL](https://xemstudio.com/files/hardware/countersunk-screws-metric/csk-m8x40.stl) — ISO 10642 M8 × 40, 90° head, thread as plain cylinder

## Questions

**What countersink for an M3 flat head screw?**

90° cone, 6.3 mm diameter at the surface, 1.7 mm deep (6.0 mm head). In a print model 6.5 mm.

**What countersink for M4 and M5 flat head screws?**

M4: 8.3 mm diameter × 2.3 mm deep. M5: 10.3 mm × 2.8 mm. Always 90° for metric (82° is the imperial standard, not interchangeable).

**Can I countersink a 3D printed part?**

Yes if there's 1.5 mm or more of material under the head and the cone is modeled, not drilled; printed cones come out clean when the part is oriented with the cone opening downward or the overhang is under 45°.

## Fits with

- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/)
- [Button head socket screws, M2–M8 (ISO 7380)](https://xemstudio.com/objects/button-head-screws-metric/)
- [Hex nuts, M2–M8 (ISO 4032)](https://xemstudio.com/objects/hex-nuts-metric/)
- [Heat-set threaded inserts, M2–M6 (for 3D prints)](https://xemstudio.com/objects/heat-set-inserts/)