1. Gauge Design
When designing a gauge to check a piece of work you need to remember that like the item itself it is impossible to manufacture it to the exact size and form therefore there is also a tolerancing system for gauge design.
The tolerances and their dispositions for gauges depend on the following:
1) The nominal size of the product.
2) The tolerance grade of the product.
3) The type of gauge e.g. plug, ring Gap etc.
Like the tolerancing system for limits and fits where we refer to BS4500 tables , there are tables for gauge design also, the reference tables for these can be found in BS 4500 part 2

2. Application of Gauge tolerancing
Plug Gauge Application
No-Go Gauge U/L = Hole U/L + H/2
No-Go Gauge L/L = Hole U/L - H/2
Go Gauge U/Limit = Hole L/L + z + H/2
Go Gauge L/Limit = Hole L/L + z - H/2
Wear Limit = Hole L/L - Y

3. Worked Example of Application