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Reference
The numbers and formulas worth keeping one tap away, in the exact form the calculators use them.
Formula sheet
Every formula on the site with variables defined and one worked example each. Printable.
ANSI Z80.1 tolerances
Sphere, cylinder, and the axis bracket table, with the boundary conventions stated.
Common vertex distances
Typical fitting values and when compensation starts to matter.
Frequently asked questions
What lives in the reference section?
The printable formula sheet, the ANSI Z80.1 tolerance tables as commonly published, and a short table of common vertex distances with the compensation rule of thumb.
Are these values authoritative?
They are teaching values as commonly published. Standards are revised and laboratories may hold tighter internal limits, so verify the edition in force before applying any figure to real work.