|
|
Posted by D Sherman [72.47.9.228] on Wednesday, July 14, 2010 at 00:23:30 :
In Reply to: Re: If not TIN coated, you can sharpen yourself.... posted by Doug in CO [75.71.232.78] on Tuesday, July 13, 2010 at 11:02:20 :
In my opinion a good drill bit sharpener is a mandatory piece of equipment in any shop. In a pinch you can grind the larger bits free-hand on a grinding wheel with a lot of practice and a cup of water, but they never turn out exactly right. An off-center sharpening job shows up as a bit that tries to go sideways or cuts an oddly-shaped hole. Generally the smaller bits (less than 3/16 or so) are hard to sharpen properly and are cheap enough to be disposable, but once you get into the 9/16 to 1" range, throwing out dull bits is not really an option. Plus, if you have a sharpener, you're not tempted to keep forcing a chipped or dull bit.
As for titanium nitride, as near as I can tell it's just a very thin gold-colored coating applied to ordinary high-speed steel bits in order to charge more for them. The coating is so thin that it can't possibly do any good, and in my experience the cheap "gold" bits wear out just as fast as the cheap black bits. The good side of that is that there's no problem with sharpening TIN coated bits yourself because the coating is really little more than paint and doesn't interfere with sharpening at all.
One good source of cheap top-quality bits used to be Boeing Surplus. It's been 20 years since I've been there, and for all I know it might not even exist any more, but it used to be that they had a huge variety of dull drills and mills sold cheaply by the pound. If you could sharpen them yourself, they were a great deal. Obviously Boeing buys the good stuff for their machine work.