The permitted range of a dimension, given as a plus and minus around nominal (bilateral), in one direction only (unilateral), or as upper and lower limits. Dimensions without a callout fall back on the title block, for example plus or minus 0.010 in for two-place decimals and 0.005 in for three-place. Every halving of tolerance pushes up cost, so experienced machinists ask which features really need it.
Tolerance on that slot is plus or minus five thou, don't waste time chasing tenths, rough it and finish it once.
Title block tolerances apply to every dimension without its own callout, so read the block before you read the part.
Also heard as
- tol
- plus-minus
Related terms
Nominal
The stated target size of a feature before any tolerance is applied.
Dead nuts
Shop slang for exactly on size or perfectly aligned, with no measurable error left.
Go/no-go gauge
A fixed gauge with one end that must fit and one that must not, for fast pass or fail checks.
First article
The first good part off a new setup or program, fully inspected before the rest of the run is made.