What size is Letter R drill bit? - FindAnyAnswer.com
2020-5-17u2002·u2002Today, jobber bit refers to the length of the drill itself. Specifically, jobber bits have a flute length between 9 and 14 times the diameter of the drill. A ½ inch diameter jobber drill will be able to drill a hole 4 ½ inches deep because it is 9 times the diameter in length, for example.
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