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| 1/2" holes?? If you use slow enough speed, cutting oil and enough pressure to ribbon the shavings you're cutting then 1 bit of each 1/4" for pilot and 1/2" for finish. If larger than 1/2" finished hole I'd put another step in there at about a 1/4" less than finished hole ie; 3/8" for 5/8" finish or 1/2" for 3/4"finish. I would get an extra or 2 as I would probably break at least one if not more if doing it free hand. Even though they may be "high speed drill bits"the real key to bits lasting is SLOOOOWW so as not to over heat the bit. About 4 or 500 rpm is plenty fast. The mag drill suggestion would make the job almost fun! 7 teeth 14 holes?????? All the teeth I'm familar with have a Ubolt for the front-----= 3 hole per tooth? | |
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Drill Bits
