Engineering reference data with stated sources and derivations. This page explains how the data is produced and where the limits are.
Last updated 2026-10-19
Engineering Reference is the publishing name used on refmanual.com. The site publishes reference tables, explanatory pages and calculators for engineering lookups. Maintenance and data corrections can be reached at contact@refmanual.com or through the correction instructions.
Responsibility for a page stays with the site publisher. A reference to ISO, ASME or a supplier identifies a source; it does not imply that the source organisation has reviewed or endorsed this website.
Pages distinguish published reference values, values derived from a stated formula, and illustrative estimates. Read the stated edition, units, material condition and method before using a number. Where available, column markers link values to their source notes.
Scripts generate repeated tables and pages; automated calculations and AI-assisted drafting can support preparation. The useful evidence is the published formula, traceable source and recorded check scope. Automated validation checks declared numerical relationships and internal links; it does not independently establish the correctness of every source or replace a technical review.
These entries record specific checks. They are not whole-site certifications or claims that every cited standard has been reviewed in full.
| Date | Pages and check | Evidence and scope |
|---|---|---|
| 2026-10-19 | 2-4½ UNC, #2-56, tap-drill chart and calculator: corrected incomplete drill coverage and prevented out-of-range clamping. | ICS tap chart for selected numbered-thread lookups and the 2-4½ drill; Guhring chart for drill equivalents and the cut-thread percentage convention. Other rows remain explicitly labelled geometric estimates. Software checks cover consistency and bounds, not physical tapping or full-standard conformity. |
| 2026-10-16 | Surface finish chart, roughness comparison, calculator and N-grade definition: corrected reversed N-grade lookup and checked all 12 N/Ra pairs. | MISUMI / Nihon Kinzoku Denchu reference table. Unit arithmetic, grade ordering and out-of-range behaviour checked separately. Process capability ranges were not independently reverified in this check. |
| 2026-10-15 | 1/4-28, 5/8-11 and #8-32: drill units and theoretical cut-thread percentages. | Guhring tap-drill reference, page 2. Compared the illustrated drills with the manufacturer’s 75% column; these are different selections, not thread acceptance limits. |
| 2026-10-15 | Ra definition and worked example: arithmetic, unit conversion and cited standard status. | Mitutoyo parameter definitions and ISO catalogue status. The ISO catalogue check is not a review of the complete paid standard. |
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A correction is checked against the cited evidence, applied to the page and its generating calculation where relevant, and covered by an appropriate numerical or behaviour check. Substantive corrections are recorded with their date and scope so readers can see what changed.
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