The Stubs Gauges
Two different scales, one name, and a great deal of confusion.
Origin
Developed by Peter Stubs of Warrington, whose files and tool steel were sold across Britain from the late eighteenth century.
The catch
There are two Stubs gauges and they are not the same. Stubs Iron Wire is the Birmingham Wire Gauge under its maker’s name, running from 0000 down to 36, with higher numbers meaning thinner. Stubs Steel Wire runs from Z down through A and then 1 to 80, and was used for drill rod and tool steel. Ordering the wrong one is an expensive mistake.
| Number | Stubs Iron (in) | Stubs Steel (in) | Note |
|---|---|---|---|
| 1 | 0.300 | 0.227 | Already different at the first number |
| 10 | 0.134 | 0.191 | |
| 20 | 0.035 | 0.161 | Iron is wire; steel is still drill-rod thickness |
| 30 | 0.012 | 0.127 | |
| 36 | 0.004 | 0.106 | The end of the iron gauge |
| 40 | — | 0.097 | Steel gauge only from here |
| 60 | — | 0.039 | |
| 80 | — | 0.013 | The fine end of the steel gauge |
Peter Stubs built a reputation for files and tool steel so consistent that his gauges were adopted by the trade as a reference. The numbered twist drill sizes still in use follow the Stubs Steel Wire gauge closely, so a workshop reaching for a No. 30 drill today is using a scale descended from a Warrington filemaker in the eighteenth century. The two gauges are frequently confused even in engineering references, which is a reasonable measure of how thoroughly the name outlived its explanation.