DRAWING DETAILS / CNC MACHINING INSIGHTS
A hole pattern may be small in the model but central to an assembly. The drawing should make clear which surfaces establish position, whether the holes provide clearance or location, and which relationship matters to the mating part.
Start with the assembly purpose
Ask what the pattern does. It may accept fasteners, locate another part, mount a component or create a service interface. The function determines which dimensions deserve attention and what information a reviewer needs before a quote or production release.
For a pattern that interacts with another component, share the relevant mating information. Our assembly-fit guide explains how that context clarifies an RFQ without requiring an entire assembly package.
Choose dimensions from meaningful references
| Drawing approach | Best use | Review question |
|---|---|---|
| Baseline dimensions | Locating multiple holes from a shared functional edge or reference. | Does every position trace back to the same intended assembly reference? |
| Coordinate callout | Showing a pattern in a clearly defined drawing coordinate system. | Are the zero point and orientation unambiguous? |
| Pattern note | Repeated holes with a complete, visible arrangement. | Are quantity, spacing, diameter and through or blind condition all stated? |
Avoid a chain of dimensions when the pattern must relate to one functional interface. A shared reference helps preserve the relationship the assembly actually needs.
State hole type separately from position
Position alone is not a complete hole requirement. Specify diameter, through or blind condition, thread callout where applicable, and any counterbore, countersink or spotface. Our guide to counterbores, countersinks and spotfaces covers the extra information required for those features.
Make the critical relationship visible
If two holes locate a mating part, show the relationship to the mounting face, locating bore or other functional reference. If the pattern only clears fasteners, identify it as a clearance pattern. The review should not have to infer the role from a rendered view.
For reference selection, see our CNC drawing datums guide. It offers a practical way to connect measurements to the part’s actual assembly function.
Questions to include in the RFQ package
- Which face or feature establishes the hole-pattern reference?
- Are holes for clearance, location, threads or a combination?
- What mating component or hardware governs the pattern?
- Which dimensions affect alignment or fit?
- Are any recesses, entry-side conditions or inspection expectations required?
Keep the pattern reviewable
ExactMach coordinates drawing-defined CNC milling, CNC turning, prototypes and custom parts around Shenzhen and Dongguan for international orders. A clear hole-pattern callout helps the manufacturing review focus on the released functional requirement.