Tolerance callouts that actually change the price
Half the tolerances we receive cost money without doing anything. A short guide to which features deserve a tight number.
Half the tolerance callouts we get quoted are decorative — a habit carried over from a CAD template rather than a decision about what the part actually needs to do. The other half are the two or three dimensions that genuinely determine whether the assembly works.
Knowing which is which before you send the drawing is the fastest way to lower a quote without changing the material or the quantity.
Mating features get the tight number
A tolerance only costs money where it constrains how we cut, fixture or inspect the part. A hole that bolts to something else, an edge that seats against another panel — those need the number you gave them. A decorative edge forty feet from any other component almost never does.
What ±0.005 in actually costs
Holding a tight tolerance on every dimension means fixturing for the tightest one and inspecting every feature to prove it, even the ones nobody will ever measure again after assembly. On a typical bracket-sized part, that shows up as inspection time billed at the same rate as the cut itself.
Loosen the features that do not mate with anything else to a standard ±0.030 in and the fixturing and inspection time usually drops enough to notice on the quote.
Datums matter more than the number
A tolerance without a clear datum — the reference surface everything else measures from — is a guess dressed up as a spec. Pick the surface that actually locates the part in the assembly and call it out. We will hold to it; without it, we pick the most conservative reading, which is rarely the cheapest one.
Tight tolerance on a feature nobody measures again is money spent proving a fact nobody needed proven.
| Tolerance class | Typical use | Cost impact |
|---|---|---|
| ±0.030 in | Non-mating edges and faces | Baseline |
| ±0.010 in | Features that mate or stack | Moderate — standard fixturing |
| ±0.005 in | Precision registration only | Highest — dedicated fixturing, full inspection |
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