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Heat-set threaded inserts, M2–M6 (for 3D prints)
What hole size do M3 heat-set inserts need in a 3D print? · Hardware · basis: vendor data (CNC Kitchen, ruthex, McMaster tapered inserts); typical values
- sizes
- 6 in table
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
Other publishers' files are linked, not hosted. "verify" = check the license at the link before commercial use.
| McMaster-Carr | Heat-set inserts for plastic (free STEP/IGES/STL per part, for your own design use; no redistribution) | STEP, IGES, STL, PDF | McMaster-Carr site terms: personal design use, no redistribution verify |
| CNC Kitchen | Threaded inserts, hole size recommendations | web | vendor page verify |
Free files
★ Free files 6 parts, generated by Xem Studio from the standard. CC BY 4.0. Threads are plain cylinders at major diameter. index.json
| insert-m2 | M2 insert envelope Ø3.2 × 4.0 (knurl not modeled) | STEP · STL |
| insert-m2.5 | M2.5 insert envelope Ø3.5 × 4.0 (knurl not modeled) | STEP · STL |
| insert-m3 | M3 insert envelope Ø4.0 × 5.7 (knurl not modeled) | STEP · STL |
| insert-m4 | M4 insert envelope Ø5.6 × 8.1 (knurl not modeled) | STEP · STL |
| insert-m5 | M5 insert envelope Ø6.4 × 9.5 (knurl not modeled) | STEP · STL |
| insert-m6 | M6 insert envelope Ø8.0 × 12.7 (knurl not modeled) | STEP · STL |
Plain text: sheet.txt · JSON: /api/geometry?object=heat-set-inserts
Fits with
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.