# Heat-set threaded inserts, M2–M6 (for 3D prints)

> What hole size do M3 heat-set inserts need in a 3D print?

- Category: Hardware › Fasteners
- Kind: Hardware
- Basis: vendor data (CNC Kitchen, ruthex, McMaster tapered inserts); typical values
- Page: https://xemstudio.com/objects/heat-set-inserts/ · JSON: https://xemstudio.com/api/geometry?object=heat-set-inserts · Plain text: https://xemstudio.com/objects/heat-set-inserts/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); linked files under their publishers' licenses

## Notes

- Hole diameter is set by the insert's knurl OD, not the thread; print the hole as listed and give 1 mm of extra depth under the insert for displaced plastic.
- Boss wall: at least 2 mm around the insert; 3 mm for M5+.
- Values differ slightly by brand; the table is the common 'short' size for each thread.

## Sizes

| thread | insert_od_mm | insert_length_mm | print_hole_mm | min_depth_mm |
|---|---|---|---|---|
| M2 | 3.2 | 4 | 3.0 | 5 |
| M2.5 | 3.5 | 4 | 3.3 | 5 |
| M3 | 4.0 | 5.7 | 4.0 | 6.7 |
| M4 | 5.6 | 8.1 | 5.6 | 9.1 |
| M5 | 6.4 | 9.5 | 6.4 | 10.5 |
| M6 | 8.0 | 12.7 | 8.0 | 13.7 |

## Where the files are

- McMaster-Carr: [Heat-set inserts for plastic (free STEP/IGES/STL per part, for your own design use; no redistribution)](https://www.mcmaster.com/products/heat-set-inserts/) — STEP, IGES, STL, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)
- CNC Kitchen: [Threaded inserts, hole size recommendations](https://cnckitchen.store/products/heat-set-insert-m3-x-5-7-100-pieces) — web — vendor page (verify at link)

## Free STEP/STL (6 parts, CC BY 4.0, Xem Studio)

Index: https://xemstudio.com/files/hardware/heat-set-inserts/index.json

- insert-m2: [STEP](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m2.step) · [STL](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m2.stl) — M2 insert envelope Ø3.2 × 4.0 (knurl not modeled)
- insert-m2.5: [STEP](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m2.5.step) · [STL](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m2.5.stl) — M2.5 insert envelope Ø3.5 × 4.0 (knurl not modeled)
- insert-m3: [STEP](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m3.step) · [STL](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m3.stl) — M3 insert envelope Ø4.0 × 5.7 (knurl not modeled)
- insert-m4: [STEP](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m4.step) · [STL](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m4.stl) — M4 insert envelope Ø5.6 × 8.1 (knurl not modeled)
- insert-m5: [STEP](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m5.step) · [STL](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m5.stl) — M5 insert envelope Ø6.4 × 9.5 (knurl not modeled)
- insert-m6: [STEP](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m6.step) · [STL](https://xemstudio.com/files/hardware/heat-set-inserts/insert-m6.stl) — M6 insert envelope Ø8.0 × 12.7 (knurl not modeled)

## Questions

**What hole size for an M3 heat-set insert?**

4.0 mm diameter, at least 6.7 mm deep for the common 5.7 mm long insert (knurl OD 4.0 mm). Give 1 mm extra depth for displaced plastic and 2 mm of wall around it.

**What hole size for M2, M2.5, M4 and M5 heat-set inserts?**

M2: 3.0 mm hole. M2.5: 3.3 mm. M4: 5.6 mm. M5: 6.4 mm. Depths 5–9.5 mm; check the brand's knurl OD, which sets the hole, not the thread.

**How hot should the soldering iron be for heat-set inserts?**

About 200–230 °C for PLA and PETG, 250 °C for ABS/ASA. Press straight and slow, stop flush, and let it cool before loading.

## Fits with

- [Socket head cap screws, M2–M8 (ISO 4762 / DIN 912)](https://xemstudio.com/objects/socket-head-cap-screws-metric/)
- [Threaded standoffs, M2.5 and M3 (hex and round)](https://xemstudio.com/objects/threaded-standoffs-metric/)
- [Neodymium disc magnets, common sizes](https://xemstudio.com/objects/neodymium-disc-magnets/)