Posted by David Sherman on Friday, December 17, 2004 at 11:30PM :
In Reply to: Drill Doctor posted by John on Friday, December 17, 2004 at 10:01PM :
I have a Grizzly knife grinder that came with a drill bit sharpening adapter. I originally bought the machine mainly to do long planer knives and chisels, but have used it more on drill bits than anything else. It sure is nice to not have to put up with dull bits any more.
I looked at the Drill Doctor, but since I really needed a knife grinder, I subtracted the price of the Drill Doctor from the price of the Grizzly knife grinder in order to make it a little more palatable. It wasn't a cheap machine, but it works well. Has a cup for cooling water, runs very smooth, includes a diamond tool for dressing the wheel. It uses a standard good-quality 1/2" Jacobs chuck, not some rinky-dink plastic chuck, and you can sharpen at any angle you want, not just the 118 deg that is most common. I used to try to sharpen the larger size drills by hand on a regular grinding wheel, and while I could certainly take the chips out of them and make an overall improvement if they were in really bad shape, I never could get them very good.
I don't think bits below 1/8" or so are really sharpenable on any conventional machine. The smaller the bit, the harder it is to get the point right in the center. If the point is off-center, the bit will wander and bore oblong, diagonal holes. '
Like all tools, you get what you pay for. The Drill Doctor is a step up, at least in convenience, from those old drill-sharpening jigs that mount to your workbench next to the bench grinder. The Grizzly machine is a good multi-purpose compromise. The next step above it would be a toolroom quality tool grinder.