Wood vs. metal drill bits

Yesterday we found a “brad point” drill bit sitting on the milling machine. Brad point bits are for wood, and not metals. Also, this bit (and most bits in the shops) had quite a bit of shank damage from the bit spinning in the chuck. This happens, but cleaning the chuck jaws with a finger and tightening the chuck as much as possible will minimize it. Finally, please let’s all make an effort to put the drill bits back where they came from after use - you know where you got it better than someone else does.

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Certainly a brad point should be used on wood and slipping can occur with dirty collets or a damaged shanks as well as a incorrect sized collet, but I would caution folks about “tightening the chuck as much as possible”. We have lost a number of draw bars from people over torquing the mill.

Clean and proper collet selection (or use the drill chuck for drilling operations) should be sufficient with the proper torque applied.

Actually, I was referring to chuck tightening and not collet. However, in fact there isn’t consensus on just how to tighten a keyed 3-jaw chuck - tighten one hole, two or three, etc. Personally I tighten at least two, and sometimes all three.

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