Threaded Heat-Set Insert Pilot Hole Size Charts for 3D Printing..
Getting the pilot hole size right is crucial when using threaded inserts in 3D printed parts. These reference tables provide clear, material-specific charts for PLA, PETG, ABS, and resin, covering self-tapping, heat-set, press-fit, and expansion inserts to ensure a perfect fit every time. We cover drilled and 3D modelled pilot holes, offering dimensions for all insert solutions.
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For guidance on installing these inserts and other threaded components into your projects, check out our helpful guide.
Installation Guide.
Heat-Set Inserts for 3D Printed Projects.
The preferred option in a large number of project types and situations. Heat-set inserts are installed by applying heat (typically via a soldering iron with specific tip) and letting the insert melt into the plastic, forming a perfect bond as it cools. The result? A clean, embedded thread that can handle repeated use without wobbling loose. Ideal for PLA, PETG, and ABS giving your projects a professional look and feel quickly and simply.
Heat-Set Inserts Pilot Hole Chart:
|
Internal Thread |
Variant |
Outer Diameter (max) |
Pilot Hole Diameter (Ø ± tol) |
Recommended Thermoplastics |
|
M3 (3 mm)
|
Non-Flanged |
4.4 mm |
4.0 mm (–0/+0.1) |
PLA, ABS, PETG, Nylon (most thermoplastics)
|
|
Flanged |
5.5 mm (flange OD) |
4.0 mm (–0/+0.1) |
||
|
M3.5 (3.5 mm) |
Non-Flanged |
5.2 mm |
4.8 mm (–0/+0.1) |
|
|
M4 (4 mm)
|
Non-Flanged |
6.1 mm |
5.6 mm (–0/+0.1) |
|
|
Flanged |
7.1 mm (flange OD) |
5.6 mm (–0/+0.1) |
||
|
M5 (5 mm)
|
Non-Flanged |
7.1 mm |
6.4 mm (–0/+0.1) |
|
|
Flanged |
7.9 mm (flange OD) |
6.4 mm (–0/+0.1) |
||
|
M6 (6 mm)
|
Non-Flanged |
8.5 mm |
8.0 mm (–0/+0.1) |
|
|
Flanged |
9.5 mm (flange OD) |
8.0 mm (–0/+0.1) |
Press-Fit Inserts for 3D Printed Projects.
Press-Fit Inserts offer a fast, simple and effective option for adding threads to a huge range of materials thanks to their unique installation method compared to other options.
Push them into an undersized hole and let friction do the rest. No heating elements, no complex setup, just pressure and precision. They’re best in rigid materials (resin, high-temp filaments, or fine-tuned PLA), and perfect when you need quick assembly and a decent mechanical grip without thermal distortion.
Press-Fit Inserts Pilot Hole Chart:
|
Internal Thread Size |
Variant (Flanged/Non-flanged) |
Max OD (insert) |
Pilot Hole Diameter (nominal + tol.) |
Hole Depth Requirement |
Suitable Thermoplastics |
|
M3 (3 mm) |
Non-flanged |
4.5 mm OD |
4.0 mm (−0/+0.1 mm) |
~4.8 mm (insert length; sits flush with surface) |
PLA, ABS, PETG, Nylon (rigid thermoplastics) |
|
Flanged |
5.5 mm flange OD |
4.0 mm (−0/+0.1 mm) |
~4.8 mm (insert length; flange 0.58 mm thick sits above hole) |
PLA, ABS, PETG, Nylon |
|
|
M3.5 (3.5 mm) |
Non-flanged |
5.0 mm OD |
4.6 mm (−0/+0.1 mm) |
~6.3 mm (insert length; flush with surface) |
PLA, ABS, PETG, Nylon |
|
M4 (4 mm)
|
Non-flanged |
6.1 mm OD |
5.6 mm (−0/+0.1 mm) |
~7.9 mm (insert length; flush with surface) |
PLA, ABS, PETG, Nylon |
|
Flanged |
7.1 mm flange OD |
5.6 mm (−0/+0.1 mm) |
~7.9 mm (insert length; flange 0.89 mm thick above hole) |
PLA, ABS, PETG, Nylon |
|
|
M5 (5 mm)
|
Non-flanged |
7.0 mm OD |
6.4 mm (−0/+0.1 mm) |
~9.5 mm (insert length; flush with surface) |
PLA, ABS, PETG, Nylon |
|
Flanged |
7.9 mm flange OD |
6.4 mm (−0/+0.1 mm) |
~9.5 mm (insert length; flange 1.07 mm thick above hole) |
PLA, ABS, PETG, Nylon |
|
|
M6 (6 mm)
|
Non-flanged |
8.6 mm OD |
8.0 mm (−0/+0.1 mm) |
~12.7 mm (insert length; flush with surface) |
PLA, ABS, PETG, Nylon |
|
Flanged |
9.5 mm flange OD |
8.0 mm (−0/+0.1 mm) |
~12.7 mm (insert length; flange 1.32 mm thick above hole) |
PLA, ABS, PETG, Nylon |
Expansion Inserts for 3D Printed Projects.
Expansion inserts offer a versatile fastening solution for 3D printed parts, particularly where dimensional accuracy or material softness poses a challenge. These inserts are engineered to expand within the mounting hole as a screw is driven in, creating outward pressure that locks them securely in place. This self-anchoring design makes them well-suited to applications involving lower-density filaments, large-layer height prints, or components where removability and tolerance compensation are important.
Expansion Inserts Pilot Hole Chart:
|
Internal Thread |
Variant |
Max O.D. (unexpanded) |
Pilot Hole Ø (nominal ± tol.) |
Hole Depth (min. requirement) |
Recommended Materials |
|
M3 (3 mm)
|
Non-Flanged |
4.0 mm |
4.0 mm (−0/+0.1) |
≥ 4.7 mm (insert length) |
Thermoplastics (e.g. ABS, PLA) and resin-based plastics |
|
Flanged |
5.5 mm |
4.0 mm (−0/+0.1) |
≥ 4.7 mm (body length); flange 0.51 mm thick (sits above surface unless counterbored) |
Thermoplastics (as above) and resin-based plastics |
|
|
M3.5 (3.5 mm)
|
Non-Flanged |
4.7 mm |
4.8 mm (−0/+0.1) |
≥ 6.3 mm (insert length) |
Thermoplastics and resin-based plastics |
|
Flanged |
6.4 mm |
4.8 mm (−0/+0.1) |
≥ 6.3 mm (body length); flange ~0.66 mm thick (flange protrudes or is recessed flush) |
Thermoplastics and resin-based plastics |
|
|
M4 (4 mm)
|
Non-Flanged |
5.5 mm |
5.6 mm (−0/+0.1) |
≥ 7.9 mm (insert length) |
Thermoplastics and resin-based plastics |
|
Flanged |
7.1 mm |
5.6 mm (−0/+0.1) |
≥ 7.9 mm (body length); flange 0.82 mm thick (sits atop surface or in counterbore) |
Thermoplastics and resin-based plastics |
|
|
M5 (5 mm)
|
Non-Flanged |
6.3 mm |
6.4 mm (−0/+0.1) |
≥ 9.4 mm (insert length) |
Thermoplastics and resin-based plastics |
|
Flanged |
7.9 mm |
6.4 mm (−0/+0.1) |
≥ 9.4 mm (body length); flange 0.99 mm thick (flange sits above surface if not recessed) |
Thermoplastics and resin-based plastics |
|
|
M6 (6 mm)
|
Non-Flanged |
7.9 mm |
8.0 mm (−0/+0.1) |
≥ 12.6 mm (insert length) |
Thermoplastics and resin-based plastics |
|
Flanged |
9.5 mm |
8.0 mm (−0/+0.1) |
≥ 12.6 mm (body length); flange 1.25 mm thick (protrudes above surface unless counterbored) |
Thermoplastics and resin-based plastics |
FAQs
Q: What size threaded insert do I need?
A: The size you need depends on your project’s thread requirements and material. Match the insert’s internal thread to your screw (e.g. M3, M4) and check the hole size charts to ensure the correct pilot diameter for your material.
Q: What size hole for a M3 heated insert?
A: Most M3 brass heat-set inserts require a 4.0 mm pilot hole in PLA, PETG, or ABS. Ensure the hole is cylindrical and slightly undersized to allow the insert to melt in and bond securely during installation. Make sure you check our reference tables for your exact insert type.
Q: What size hole is a M2 brass insert?
A: A typical M2 brass insert needs a 3.0 mm to 3.2 mm pilot hole, depending on the variant and plastic type. Use a tighter hole for soft materials like PLA, and a slightly looser fit for harder plastics or resin. Make sure you check our reference tables for your exact insert type.