Heat-Set Insert Test Block with Graduated Hole Sizes

This simple yet practical calibration model is designed for situations where you need a range of precisely sized holes to test the fit of parts — such as heat-set threaded inserts, tubing, or dowel pins.

The block features:

• A row of stepped holes increasing in small increments (e.g. 3.7 mm → 3.9 mm in 0.1 mm steps).
• Matching guide tubes above each hole to help center tools or inserts.
• Through holes that go all the way through the base, allowing easy push-through or inspection.
• A beveled corner marking the smallest hole side, so you always know where the sequence begins.
• Automatically scaled base size, so you can easily adjust the diameter range and step size in the OpenSCAD parameters.

Ideal for:

• Testing hole tolerance for press-fit or interference-fit parts
• Calibrating hole compensation on your printer
• Checking insert or bushing fit before modifying a real project

You can easily edit the .scad file to adjust:

• Minimum and maximum diameters
• Step increment
• Tube height, wall thickness, and base thickness

Printing tips:

• Print flat on the bed with 100% infill for consistent hole sizing.
• PETG or ABS recommended if testing heated inserts.
• No supports required.