M3 Heat-Set Insert Hole Tolerance Test Block

This simple test block is designed to help you determine the optimal hole diameter for M3 heat-set inserts on your 3D printer and filament setup.

The model includes a series of labeled holes ranging from 4.1 mm to 4.3 mm in diameter, allowing you to quickly evaluate which fit works best for your inserts.
It’s especially useful for tuning tolerances affected by factors such as printer calibration, filament shrinkage, and layer adhesion.

How to Use

Print the test block with your standard settings.

Heat up your soldering iron or heat-set tool to the temperature suitable for your insert material (typically ~200–230 °C for brass inserts).

Test-fit the M3 heat-set inserts in each hole (4.1 mm → 4.3 mm).

Observe which hole provides the best balance between insertion force and holding strength.

Model Details

Hole diameters: 4.1 mm, 4.2 mm, 4.3 mm

Optimized for M3 brass heat-set inserts

Compact, quick print (≈17 min, ~8 g of filament)

Ideal for tolerance calibration and printer/material comparison