What is a press fit in 3D printing?

A press fit means the hole is slightly smaller than the insert, so the insert must be pressed in with force. The interference between the parts creates friction that holds the insert in place without glue.

How much interference should I use?

For bearings in PLA, 0.03-0.08mm interference works well. Too much interference can crack the printed part. Start conservative and test. Remember that FDM holes already print slightly small, which adds to the effective interference.

Are heat-set inserts better than press-fit?

Heat-set threaded inserts are generally the best solution for 3D printed threads. They melt into the plastic using a soldering iron, creating a very strong bond. They resist pull-out much better than printed or tapped threads.

How thick should walls be around a press fit?

Minimum 30% of the insert diameter, with an absolute minimum of 2mm. Thin walls will crack or deform during insertion. For high loads, increase to 50% of insert diameter.

3DPrintCalcs

Press Fit Calculator — Interference Fit Dimensions

Determine interference fit dimensions for inserting bearings or bushings.

Insert Diameter

OD of bearing/bushing/insert

Printer Tolerance

Insert Type

Material

How We Calculate This

Press Fit Calculations

Hole diameter = Nominal - Base interference + Printer tolerance
Actual interference = Nominal - Hole + Printer tolerance
Min wall = max(2mm, Nominal x 0.3)
Insertion force estimated using Lame thick-wall cylinder equations

The calculator compensates for FDM holes printing smaller than designed. The actual interference combines the design interference with the printer tolerance effect.

Frequently Asked Questions

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Hinge Calculator

Design print-in-place hinges with correct clearance and pin dimensions.

Snap Fit Calculator

Calculate cantilever snap fit dimensions for secure clip connections.

Last updated: February 2026

All calculations are estimates. Always verify settings with test prints before committing to final prints.