When this applies
- No drawings exist for a part you must replace
- The original supplier will not release documentation
- You want a second source for a sole-sourced component
- A part needs redesign to fix a recurring failure
The four things that must be recovered
Geometry is only one of them. A usable definition also needs material, heat treatment or temper, surface finish and the tolerances that matter. A shop can measure geometry from your sample; the rest usually needs a combination of testing, function analysis and judgement.
- Geometry — from measurement, CMM or 3D scan
- Material — by identification testing or from function
- Condition — hardness, temper, coating or plating
- Tolerance intent — which fits are functional
Worn samples and nominal dimensions
A used part is smaller than it started on every wear surface. Good reverse engineering restores nominal dimensions by reasoning from the mating parts and standard fits, rather than copying the worn measurement. Send the mating components when you can — a shaft and its housing together tell a far more complete story than either alone.
Tolerancing is where the cost sits
Applying tight tolerances everywhere because the true values are unknown can multiply cost several times over. Identify the two or three features that actually locate or seal, tolerance those properly, and leave the rest at standard machining tolerances.
RFQ checklist
Include these in your request and suppliers can quote without a round of questions.
- What the part does and how it failed
- Sample condition — new, used or broken
- Mating parts you can supply or describe
- Whether you want a model and drawing delivered
- Quantity now and likely repeat quantity