EVIDENCE
Methods
Workshop check, manufacturer inspection and a UKAS certificate are different documents.
A claim should carry enough context to check it. These notes distinguish what a document says, what a calculation assumes, and what an experiment actually measured.
Four kinds of evidence
| Label | Meaning |
|---|---|
| Source-based note | An explanation of identified publications and their limits |
| Calculated example | Arithmetic with stated assumptions; no experiment implied |
| External measurement | A result attributed to its original author, sample and conditions |
| Original measurement | Our own documented experiment; none is included on these pages |
Workshop check, manufacturer inspection, UKAS certificate
A shop record shows how a named instrument read named blocks on a dated occasion. A manufacturer inspection sheet is the maker’s outgoing test. A UKAS certificate is a laboratory report with a stated uncertainty and a defined object. Calling a shop check “calibrated” without that certificate overstates the evidence. The distinction is written out in Workshop check versus a UKAS certificate.
What a documented length test needs
A result presented as an original measurement needs the instrument identity, the block identities and grades or certificate numbers, temperature, contact method, the raw repeats, photographs where they support the claim, and a sentence that states the limits. A reading taken as received stays separate from any later adjustment. Anvil parallelism needs optical parallels or a laboratory report; a single block reading does not establish it.
These notes cover 0–25 mm outside micrometers and digital calipers. Other instrument types are not covered by this shop-check method.
Keep a record
The download contains column headings and one empty row, without fabricated sample readings. It is a documentation aid, not a test procedure and not a certificate.
Download blank workshop-check record ↓How sources are chosen
These notes prioritise identifiable original work and documented methods. Independent author sites, manufacturer publications, regulator guidance and community questions serve different purposes. A forum question can reveal a problem but does not establish a correct answer.
The workshop notes cited here include Rick Sparber for published inch tables and a temperature cross-test, Machinist Guides for procedure structure, Practical Machinist for the boundary that optical parallels are a different check, NPL GPG 40 for UK use conditions, and ISOBudgets for the resolution-term teaching formula. Their work is attributed rather than presented as a MeasureProof result.
Review, revisions and corrections
These notes are attributed to MeasureProof. They are not a review by a named metrologist or an accredited laboratory. If a named person reviews a page, that person and the scope of the review will be identified.
The date on a page marks when the text or sources were last checked. It does not mean an instrument was tested that day. Corrections identify the changed claim and its basis. Corrections with the page, passage and source.
Commercial relationships
The operator also owns instrument retail sites. A related retail link is commercial context, not independent evidence. Such links are disclosed beside the link; ownership never substitutes for testing. See the commercial disclosure.
Policy text reviewed 23 September 2026.