Methodology — Woodcraft Parts Workshop

Pure calculators, published constants, fixed fixtures

Each calculator is a pure function: the same inputs always produce the same outputs, no calculation happens anywhere except in that function, and the page you read renders its results from the same code the browser runs. Every constant a calculator uses — bands, allowances, section lengths, coverage rates — is printed in that tool's own "How this works" block, rendered from the same exported values the calculation reads, so the page cannot show one number and compute with another.

Each tool also carries a fixed set of worked examples — fixtures — that are tested automatically against the calculator on every change. The worked example shown on each tool page before you calculate is the first fixture of its set, labelled as a worked example; it is never presented as your result. If a constant, formula or rounding rule ever changes, the fixtures and the published methodology must change in the same release.

Units policy

Millimetres are the primary unit sitewide, with inches as a secondary reading where they help — except on the FasTrack Length Calculator, where inches are primary and no metric is shown, because that is the system the track is specified in. Conversions use 25.4 mm to the inch exactly. Internally each calculator works in the units that keep its arithmetic exact — micrometre integers for dowel fits, eighths-of-an-inch integers for FasTrack, square-metre floats for sanding areas, millimetre floats rounded only at defined points for the workbench and bird box planners — and rounds only where its methodology says it rounds.

The rounding vocabulary

Every rounding step in every tool uses one of four named rules, so "rounded" never means "adjusted somewhere you cannot see":

halfUp — round half away from zero: exact halves go up in the positive domain.
to5 — round to the nearest 5 mm, halves away from zero.
ceilInt — the smallest whole number at or above the value, used where you cannot buy or cut a fraction of a thing.
frac8 — inches to the nearest eighth, with the fraction reduced and written with a solidus (1 3/8 in), never as special fraction characters.

Displayed decimals use halfUp at the stated precision. Each tool's methodology block names which rule applies at which step.

The honesty policy

These are the commitments the whole site is written under:

Facts from the site's external sources — the HSE, the RSPB and the LCCA — appear only as each tool's specification allows, and always with a superscript reference resolving to that page's sources ledger: full title, publisher and URL, with the access date.
Editorial heuristics — bands, allowances, coverage rates, tooth-count ranges — are labelled with the phrase "workshop rule of thumb" and never carry a source reference, so a sourced fact and a bench judgement can never be mistaken for one another.
Nothing anywhere on this site may claim credentials, years of experience, an address, a phone number, staff, reviews, testimonials, usage counts, test results, or continuity with any business that previously traded from this domain.

How sources are cited

A superscript number in the text resolves to the sources ledger at the foot of the same page, and every reference the site relies on is also listed centrally on thesources page — title, publisher, URL, access date, and which tool or page uses it. Reference numbers are global: the same number means the same source everywhere on the site. Where a source is print-only, the ledger says so rather than inventing a link.

Planning aids, not certification

This is a planning aid, not an engineering or safety certification. Every tool repeats that sentence in its own limitations, and means it: the calculators return starting points to confirm against the work, the machine's manual and your own judgement — never a substitute for any of them.

Each tool's methodology

Every tool documents its own inputs, method, rounding, limitations, worked example and sources in a "How this works" block on its page: