Try looking into Drill Bits. We commonly use 4 overlapping, unconnected, and varying standards.
- Fractional Inch
- Number, Commonly 1-60, but there are many more.
- Lettered, A-Z
- Decimal Metric
Check out the chart.
For even more fun, let’s say I wanted to tap a hole for a 1/4-20 bolt, then I’d use a .201" dia drill, which is a #7, but if I wanted a through hole for it, then I’d use a .257" dia drill which is an F. So fraction, number, and letter size all in one go. Better yet, what if I wanted a 1/4" hole (.250" dia)? Why I’d use a 1/4 bit, or an E bit, because they’re the same damn thing.
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