What is the most common bearing for 3D printers?

The 608 bearing (8mm bore, 22mm OD) is the most common in 3D printing projects, often used for wheels, rollers, and spool holders. 625 bearings (5mm bore) are also popular for smaller mechanisms.

Should I press fit or glue bearings into printed parts?

Press fit is preferred as it allows bearing replacement. Design the seat 0.05-0.1mm smaller than the bearing OD (accounting for printer tolerance). If the fit is too loose, a drop of CA glue or Loctite secures it permanently.

How do I account for FDM holes printing small?

FDM holes typically print 0.1-0.3mm smaller than designed. This calculator adds your printer tolerance to the seat diameter to compensate. Test with a calibration print and adjust the tolerance value accordingly.

Can I print bearing races instead of using metal bearings?

For low-speed, low-load applications, printed journal bearings (plain bearings) can work. Use Nylon or PETG for the bearing surface. For anything above 100 RPM or with significant load, use proper metal ball bearings.

3DPrintCalcs

Bearing Calculator — Seat & Shaft Dimensions

Calculate bearing seat dimensions and tolerances for standard bearings.

Bearing SizeSelect bearing size or choose Custom

Fit TypePress = held by friction, no glue; snug = hand push, removable; loose = drops in, needs a clip

Printer Tolerance

How much holes print undersized

How We Calculate This

Bearing Seat Calculations

Seat diameter (hole) = Bearing OD + Fit offset + Printer tolerance
Shaft diameter (peg) = Bearing bore + Fit offset − Printer tolerance
Seat depth = Bearing width + 0.2mm clearance

The seat is a hole and FDM holes print smaller than designed, so the printer tolerance is added to the modelled seat so it lands on size. The shaft is an external peg and FDM outer walls print larger than designed, so the tolerance is subtracted from the modelled shaft so it still passes through the bore. A negative fit offset makes the seat tighter (press fit, held by friction); a positive offset makes it looser (drop-in).

Frequently Asked Questions

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Determine interference fit dimensions for inserting bearings or bushings.

Last updated: February 2026

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