Reply by runswithscissors

  • Advertise with us

Posted on How do you identify good steel from bad in tools like drill bits

View runswithscissors's profile


2727 posts in 1994 days

#1 posted 12-15-2012 08:31 AM

I agree, cobalt bits are best for steel. But it doesn’t matter what the metal is, a dull bit won’t cut. Even aluminum needs sharp bits. I often drill stainless, and always use cobalt. In an emergency, there’s another way if you don’t have cobalt, but won’t go into that now. And Drill Doctor is good. Haven’t tried other systems, though I do sometimes sharpen by hand/eye, but it’s hard to get consistent results. As for spade bits, many now have spurs to scribe the circle (way better than the old type), and some kind of fancy grind to provide relief. But how to sharpen them? Before that type ever came on the market, I started sharpening regular spade bits with a rat tail file or chain saw file. I try to use a file with a diameter that spans from the outer perimeter to the root of the point. I then file a hollow (half circle, more or less) in between the edge and the point. By tilting the file a little, I create the necessary relief. It’s possible to sharpen this way and get very nice sharp spurs, and the bits cut far faster and cleaner than a regular spade. Almost as nice a hole as a good brad point. Thing is, I can take a new spade bit and file it this way in about 10 minutes. When they get dull it takes about 2 minutes or less per side to sharpen. I’m convinced they perform better than the patented ones. (I’m not thinking about the Bosch, as I haven’t tried them). Oh, to control break out at the end, either use a backing board that you drill into a little ways, or drill just until the point starts to show. Then flip over and drill from the other side, using the little hole as your target.

-- I admit to being an adrenaline junky; fortunately, I'm very easily frightened

DISCLAIMER: Any posts on LJ are posted by individuals acting in their own right and do not necessarily reflect the views of LJ. LJ will not be held liable for the actions of any user.

Latest Projects | Latest Blog Entries | Latest Forum Topics