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 Size

Fit Type

Printer Tolerance

How much holes print undersized

How We Calculate This

Bearing Seat Calculations

Seat diameter = Bearing OD + Fit offset - Printer tolerance
Shaft diameter = Bearing bore + Fit offset + Printer tolerance
Seat depth = Bearing width + 0.2mm clearance

The printer tolerance compensates for FDM holes printing smaller than designed. Press fit seats are designed slightly undersized so the bearing pushes in and is held by friction.

Frequently Asked Questions

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Last updated: February 2026

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