Content deleted Content added
Line 58:
Number and letter sizes are commonly used for [[drill bit#Twist drill bits|twist drill bits]] rather than other drill forms, as the range encompass the sizes for which twist drill bits are most often used.
The gauge-to-diameter ratio is not defined by a formula, but is instead based on, but is not identical to, the [[Stubs Steel Wire Gauge]], which originated in Britain during the 19th century.<ref>{{Cite journal|last=Pöll|first=J. S.|date=June 1999|title=The story of the gauge
Number and letter gauge drill bits are still in common use in the U.S. and to a lesser extent the UK, where they have largely been superseded by metric sizes. Other countries that formerly used the number series have for the most part also abandoned these in favour of metric sizes.
| |||