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LatheRPM calculatormetric

As a jeweler you really should be using metric drill bits. Period, end of discussion. But I decided that I should include additional information as it makes the discussion complete. A common standard for metric drill sizes is the Renard series, which uses a simple factor to determine the diameter. I will not go into that as most jewelers use very small drill bits. I personally rarely ever use one over 5mm in size. for me, as a general rule, I tend to buy my drill bits in sizes that allow me to set round gems. The drill bits that I use every day range in size from 0.8 mm (0.0025 ct) to 5.0 mm (0.50 ct) in diameter and I tend to buy them in the sizes closest to the gems I set.