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Registered
Join Date: Jan 2002
Location: Long Beach CA, the sewer by the sea.
Posts: 38,233
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RPM is not as much of a factor as cutting speed. At that diameter the math can be worked out as to what the cutting speed is but I can say that's too high. Way too high. 400 is for more like a 1" drill twist bit. Real small bits are used in the low thousands of RPM.
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