A19 · Reference edition 2026.11
Redundant constraints — Recording and revision
Two contacts intended to locate the same direction can compete when the part or fixture varies. More contacts do not guarantee better repeatability.
Scope and purpose
A reference record should allow another reader to reconstruct the intended description. Keep the identifier, context and revision together. When information changes, explain the change and retain enough of the earlier description to understand what was superseded.
Working notes
This reference collection concerns light, offline dimensional-inspection layouts. It brings locating concepts, component descriptions and revision records together without substituting for an engineered fixture design. The drawings are original explanatory diagrams. Reference IDs identify documents, not commercially tested products. Read the scope and limitations alongside each example, and keep the actual part drawing and inspection requirements available when reviewing a proposed layout.
Practical example
Highlight contacts sharing a normal direction and describe whether each is locating, supporting or floating.
| Reference record | Interpretation |
|---|---|
| A19 | Redundant constraints |
| Scope and purpose | Two contacts intended to locate the same direction can compete when the part or fixture varies. More contacts do not guarantee better repeatability. |
| Limits and interpretation | Do not remove or relax a real constraint without an engineering review. |
Review checklist
Check the identifier; describe the observation and its source; date the revision; link affected figures; distinguish confirmed facts from open questions.