How to use the wiki

This wiki has three kinds of page, and it's worth knowing which one you're reading, because they promise different things.

The three kinds of page

Tutorial — a path from start to finish, with a result at the end. "Model the gland", "generate the electrode". Follow the steps in order and you end up in the same place. A tutorial deliberately doesn't explain every alternative: it picks one and goes.

Reference — the table, the parameter, the value. You don't read it end to end, you look things up. The pages for the site's calculators are reference with a tool alongside.

Explanation — why something is the way it is. Why an O-ring's squeeze changes with the cross-section, why you balance springs by rate and not by load class. This is what you read once and don't need to read again.

Where the numbers come from

The rule that applies to the whole site, and therefore to the wiki:

No engineering data is published unless it has been checked or derived. Where the source couldn't be verified, either the value stays an input field, or the page says outright that it needs to be checked.

That isn't modesty. A wrong part number makes someone buy the wrong part, and a wrong dimension becomes tooling machined out of spec. When a value here is marked check, check it before machining.

What goes where

Conventions

Dimensions in millimetres, unless stated otherwise. Force in newtons, torque in N·m, spring rate in N/mm.

When something looks like this, it's literal: a command, file or field name, to type or search for exactly.

Boxes like this mark what usually goes wrong:

Watch out. Catalogue values carry manufacturing tolerance. Die spring rates, for example, vary by ±10% at some manufacturers. For fine preload, measure the part.

Found an error, or a page that promises and doesn't deliver? That's a defect, not a detail — the wiki is only worth something as long as it can be trusted.