n× Pattern of features
Pattern of features · Ubicación · ISO 1101 + ASME Y14.5
Example in plan
How to interpret it
The geometric requirement applies to a repeated pattern of features (several holes, pins, etc.), not just one: the tolerance is evaluated on every feature of the pattern from the basic dimensions on the drawing.
What controls
Indicates, by means of the numeric prefix (4×, 6×, etc.) or the note “PATTERN”, that the geometric tolerance in the feature control frame applies to the complete set of repeated features as a single pattern, not to each feature in isolation with its own dimensional tolerance. All the features in the pattern share the same datum reference frame and the same theoretical tolerance zone framework.
How to verify
On a CMM, the complete pattern is measured in a single program routine, evaluating each feature against its basic location within the same datum reference frame; the result is usually reported as the worst case (the feature with the largest deviation) in addition to the individual details. In series production, a go/no-go gauge made to the virtual condition of the whole pattern simultaneously is much faster than measuring hole by hole with conventional instruments.
tolerance zone
Each feature in the pattern has its own identical tolerance zone, all referenced to the same datum reference frame.
Workshop guideline values
- General
- 0.1–0.3 mm per feature on hole patterns in general machining.
- Accuracy
- 0.03–0.08 mm on fastener or tight dowel pin patterns.
- High precision
- 0.01–0.02 mm on precision patterns (templates, interchangeable fixtures).
Guidance only: the drawing's value always wins.
Common mistakes when interpreting it
- Measuring each feature in the pattern as an isolated position with its own origin: they all share the same datum reference frame, so they must be evaluated in a single program routine, not one by one from scratch.
- Reporting only the average deviation of the pattern: what matters for accepting or rejecting is the worst case (the feature with the largest deviation), not the mean of them all.
How to get it in the workshop / if it comes out of tolerance
The 4×, 6× or “PATTERN” prefix changes the inspection: the complete pattern is evaluated, not each hole with a stand-alone dimensional tolerance.
If only one hole in the pattern fails and the rest are fine, suspect the drill (asymmetric wear or wander on that particular hole) before the program: rework with a spot drill at that location first. If the WHOLE pattern comes out shifted as a block but keeps its spacing correct, the error is in the work offset (G54) or the workholding, not in machining the pattern itself — do not re-machine hole by hole, correct the work offset.
Alternative symbol:4×
Other symbols in Location
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