Are Irwin cobalt drill bits coated like the titanium ones? If the cobalt bits are rockwell hardness 66 - 67 HRc, what hardness are the titanium bits? Once you sharpen a cobalt bit and the gold coating is gone, is it just a regular bit?
Cobalt bits are not coated, they are cobalt steel through and through. At t... read more
How do I resharpen Speedbor flat bits?
Use a small file to sharpen the top of the cutting edge and inside the spur... read more
IRWIN Lettered and Numbered Drill Bits information:
Letter and numbered drill bits were developed to make up the gaps in betwee... read more