When one part is machined at several suppliers, tolerances can drift at the seams. Consistency comes from controlling the references, not just the numbers.
Lock the datums
Define datum references in the drawing and require every shop to measure from them. Without shared datums, “in tolerance” at shop A may not assemble with shop B.
First article at each source
Require a first article from every supplier, not just the first one. It proves each process holds the callout before volume runs.
Share the measurement method
Specify how features are inspected (CMM program, probe strategy) so results are comparable across shops.
Coordinate, don’t juggle
A single coordinator—internal or via a partner like RapidKin—owns the drawing interpretation so suppliers don’t diverge.
FAQ
Biggest risk in multi-supplier runs? Datum and method mismatch. Fix it in the drawing.
How tight can we hold across shops? ±0.01 mm is repeatable with shared datums and FAIs.
