DRAWING DETAILS / CNC MACHINING INSIGHTS
General tolerances can make a drawing more complete, but they are not a substitute for identifying the dimensions that control fit and function. Buyers get a more useful CNC review when title-block notes, specific callouts and inspection priorities work together.
Separate general requirements from critical features
A general tolerance note can provide a baseline for dimensions that have no individual requirement. Critical interfaces should still be identified directly. Examples include mounting relationships, mating bores, sealing faces, hole patterns and other features that determine whether parts assemble as intended.
Our CNC tolerance guide explains why tolerances are most valuable when connected to fit, alignment or performance rather than applied uniformly without a functional reason.
Make the title-block note visible and current
If the drawing uses a general tolerance convention, include it in the controlled PDF and ensure it belongs to the released revision. Do not rely on an outdated template, a separate email or a verbal statement. The manufacturing review should see the same current requirement package that defines the part geometry.
See our drawing revision control guide for practical steps to keep drawings, models and RFQ references aligned.
Use specific dimensions where the assembly needs them
| Feature type | What to clarify |
|---|---|
| Mating interface | Which surfaces or features establish the fit and which dimensions control it. |
| Hole pattern | Functional reference, complete hole callout and alignment relationship. |
| Surface relationship | Whether flatness, parallelism or perpendicularity affects the function. |
| Cosmetic or clearance feature | Whether a general requirement is sufficient instead of an individual restriction. |
Link inspection to function
When a specific feature is important, identify what needs verification and from which drawing reference it should be understood. General notes are useful context; focused inspection notes are what make a functional requirement reviewable before production release.
Our inspection requirements guide covers the details buyers can include for critical drawing-defined features.
RFQ questions to answer
- Is there a visible general tolerance note in the released drawing?
- Which dimensions are critical to assembly or performance?
- Are functional features individually called out where needed?
- Does the model match the same drawing revision?
- Which features need inspection attention?
Make the drawing hierarchy clear
ExactMach coordinates drawing-defined CNC milling, CNC turning, prototypes and custom parts around Shenzhen and Dongguan for international orders. Clear general notes and specific functional callouts help the manufacturing review understand the released requirement before production begins.