Understanding Tolerances in CNC Machining
Last updated
Tolerance is the single biggest lever you have on cost. Get it right and the part is cheap, fast and repeatable. Get it wrong and you pay for accuracy you do not need.
What tolerance actually means
Tolerance is the allowable variation on a dimension. A 10.00 mm hole within 0.05 mm tolerance is acceptable between 9.95 mm and 10.05 mm.
Typical CNC milling and turning tolerances
- General machined features: within 0.1 mm
- Precision features: within 0.05 mm
- Critical fits and bearing seats: within 0.01 mm
How tolerance drives cost
Tighter tolerances need more setups, slower cuts, finer tooling and more inspection. Calling out 0.01 mm on every dimension makes the part expensive without making it better.
A better approach
Tolerance the features that matter. Leave the rest at a general note. Our Sydney engineers are happy to review your drawing and suggest where to relax dimensions without affecting fit or function.
Brief us on a CNC machining or prototyping project and we will quote against your real tolerance needs.