Posted by Sherman in Idaho [72.47.153.158] on Wednesday, August 05, 2015 at 14:15:20 :
In Reply to: Drill Bits OT posted by The Dodge Boys [173.49.177.213] on Wednesday, August 05, 2015 at 10:39:35 :
Cobalt bits are good. The gold-colored "TiN" ones are no better than whatever metal is under the coating. But as others have said, the key to bit life is to keep the bit cutting all the time. Once it starts to slide across the surface it will overheat and dull quickly. This is especially important on stainless because stainless work-hardens and becomes un-cuttable. Any cutting fluid is way better than none. Water, motor oil, alcohol, diesel, etc may not be as good as proper cutting oil but they're better than dry. For awkward angles, there's a dry stick material called "Tap Magic" that is better than nothing. It's mainly for use on taps, where it stays in place better, but it helps some on drills. Even soap can be used in a pinch. The only exception is cast iron which should be drilled dry.
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