The fastest way to overpay for machined parts is to tolerance everything tightly. Every tighter callout adds measurement, slower feeds, and scrap risk.
The cost curve
Moving from ±0.05 mm to ±0.01 mm can double inspection effort and hurt yield. Going to ±0.005 mm or better often requires specialized process control.
Decide by function
Ask: does this dimension affect fit, seal, or motion? If yes, tolerance it. If it is a non-critical length, leave it at stock (±0.05–0.1 mm).
Use GD&T for position
A hole that must sit precisely is better controlled by a position tolerance with datums than by plus/minus on X and Y, which double-counts error.
Communicate clearly
Note “critical” features in your notes so inspection focuses there. Our quality process plans measurement around your true critical dims.
FAQ
Is tighter always better quality? No—unused tightness is just cost. Tolerance to function.
Default tolerance if I say nothing? Shops apply stock ±0.05 mm; confirm during review.
