5 min readRead the complete control before quoting a check
Start with the controlled surface, geometric symbol, tolerance and datum references on the current drawing. A diameter requirement and a runout requirement answer different questions. A shaft may be within its size limits while the indicated surface varies too much when rotated about the specified reference. Keep size checks and geometric checks as separate inspection characteristics.
KEYENCE describes circular runout at individual circular sections and total runout over the controlled surface. Use the nominated drawing standard and its complete callout to decide which requirement applies. Words such as runs true or concentric should trigger a clarification rather than an undocumented substitution for the specified control.
An indicator may report a maximum-to-minimum change during rotation. Record what was measured and how the part was supported before treating that reading as evidence for a particular drawing requirement. The instrument display alone does not define the datum, coverage or acceptance rule.
Agree a datum setup that can be reproduced
Identify the actual datum feature or datum system from the drawing. Ask the inspection specialist to show how the selected fixture represents it. A convenient production diameter, centre hole or holding surface only becomes the acceptance reference when that choice is consistent with the drawing and the agreed method.
The setup sketch should show support locations, restraint, measurement contact direction and the area being evaluated. Note the part condition, contact-surface preparation and any agreed orientation or seating procedure. For long or flexible parts, record support and clamping conditions so later checks do not compare different loading situations.
Decide whether the method is an indicator setup, a roundness instrument, a coordinate measurement or another appropriate approach. V-blocks or centres may suit a particular method, but should not be assumed to reproduce every specified datum. Choose the method with the inspection specialist and record the reason it answers the actual requirement.
Separate radial, axial and full-surface coverage
A journal and a shoulder require different measurement directions and controlled areas. Mitutoyo’s guide illustrates radial and axial runout separately. Mark the journal sections or face locations to be checked, and identify any interrupted surface or access restriction that affects the measurement plan.
For circular runout, the agreed procedure must cover the required circular sections. For total runout, define the evaluation of the controlled surface as a whole. Completing one revolution at a single location does not by itself document the full-surface requirement. State the coverage and reporting method rather than using the instrument movement as the definition.
Agree the inspection stage: for example, which specified finish condition is to be evaluated and whether a later operation changes a controlled surface. Connect the requirement to the feature number on the inspection report. This prevents a valid check at one operation from being silently reused as final acceptance after the component has changed.
Put the purchasing and inspection decisions in one record
Use the worksheet below to align the supplier’s proposed method with your receiving plan before samples are made. The entries are project decisions, not a universal runout capability or a fixed inspection prescription. Link the approved setup to the drawing revision and the requested report.
Specify which records are needed for samples and which are needed for subsequent lots. Identify part or sample IDs so a retained result can be traced to the physical item. Where results depend on instrument evaluation settings, record the relevant settings and method revision with the actual measurements.
Set the acceptance criterion from the drawing and any agreed inspection procedure. Have the inspection specialist address method suitability and measurement uncertainty where they affect the decision. A quotation should identify the requested checks and records separately so the same evidence is included in competing offers.
| Decision | Agree before the check | Retain with the order |
|---|---|---|
| Drawing control | Feature ID, current revision, symbol, tolerance and datum references | Controlled drawing and characteristic list |
| Datum realisation | Support features, restraint and setup orientation | Approved setup sketch and fixture identification |
| Coverage | Radial or axial direction; sections or full controlled surface | Measurement plan tied to feature IDs |
| Part condition | Inspection stage, specified finish and agreed preparation | Condition and preparation recorded with the result |
| Method and result | Instrument, relevant settings, sample identity and actual readings | Report with method revision and traceable part IDs |
| Decision | Drawing criterion, repeatability review and any authorised disposition | Accepted result or separately recorded concession / action |
Resolve different readings against retained evidence
An illustrative receiving case starts with a supplier’s passing journal result and a higher reading at the buyer. First confirm that both teams measured the same part identity, revision and controlled feature. Preserve both original readings and their setups. A different support diameter or contact position may mean the two results did not evaluate the same condition.
Next compare seating, restraint, surface condition, measurement direction and coverage. Use an agreed repeatability check to understand setup variation. Record any authorised cleaning or reseating step and its effect. Repeatedly moving the part until a favourable reading appears is not a documented acceptance procedure.
If the methods still disagree, isolate the affected material and refer the result to the designated quality decision maker. Agree the next verification method and disposition using the specified requirement. Keep concession or rework approval separate from a conforming result, then preserve the resolution for the next order.
Carry the same basis from RFQ to repeat order
Send the controlled drawing and identify the journals, shoulders and datum features that matter to your assembly. Include the proposed inspection scope, sample quantity, lot quantities and required records. Link the inspection requirements to the feature numbers instead of asking only for a general quality report.
At sample approval, retain the accepted drawing, setup sketch, method and actual results. Use the first-article and production-sampling guide to separate initial verification from repeat-lot inspection. A change in material, heat treatment, finish or manufacturing sequence should prompt review of the relevant acceptance conditions.
For repeat orders, identify which approved basis still applies and mark changes explicitly. Record commercial scope and delivery requirements alongside the inspection deliverables. The revision-change checklist helps keep an old passing report from being attached to a different configuration.
Questions before shaft inspection
Is a diameter check enough to verify shaft runout?
No. Diameter size and runout are different characteristics. Inspect the specified surface relative to the drawing datum using the agreed method and coverage.
What runout limit should I put in the RFQ?
Use the tolerance and control from the approved drawing. Agree the datum setup, surface coverage and required records; do not substitute a universal supplier capability value.
Can V-blocks be used for every shaft runout check?
The support method must represent the specified datum and suit the controlled feature. Ask the inspection specialist to confirm the method rather than assuming one fixture is suitable for every drawing.
Does one indicator trace establish total runout?
A single circular trace does not establish evaluation of the entire controlled surface. Define the coverage and method required by the drawing before accepting the report.
What should I send when receiving and supplier results differ?
Share the part identity, drawing revision, controlled feature, both actual results, setup sketches, support and contact locations, part condition and method details. Preserve the original results while the discrepancy is reviewed.
What records should accompany repeat orders?
Retain the approved drawing, setup and inspection method, agreed sampling scope and traceable results. Review changes to the component or acceptance method before applying the previous basis.
