- Joined
- Sep 18, 2017
- Messages
- 22
I do use it, and the documentation is near non-existent. Actually, it works very well. There is a (poor quality) video on youtube under "U3" as the search term that makes it more clear. The part that I had to figure out is what the ideal clocking of the drill should be. I set it up to look like an hourglass as it enters the grinding wheel from the normal direction. Then you need to set a stop at the end of the bit, grind one side, then roll the bit 180 degrees and grind the other side. Once set up, it is faster than using my drill doctor and more versatile. The fixture makes a good grind profile and you can get good grinds on small drill bits (less than 1/8 is possible) up to fairly large S&D bits. Oh, you want to grind at a 59 degree angle with the fixture for a 118 degree included angle. Sorry for the weak instructions, but once you see it done on youtube and grind a bit or two, the concept will lock in and you will be rolling. Alternatively, you can grind the four facet pattern. Definitely read the Workshop Practice series tool grinding book (#38) by Harold Hall under downloads on this site if you don't have it already. It explains a lot in a very short space about sharpening drills, including angles, web thinning, split and chisel points, and so on. Hall uses a bench grinder adapter (like the Craftsman) for his main example, which works on the same principle as the drill fixture we have.
Thanks for the reply. I've watched that "U3" video you mentioned, and I've been trying to make sense of his written charts and instruction. It seems that my attachment has a couple minor differences than his, and consistency is eluding me. I understand what you're saying about clocking the bit. I've read #38 a while back, but I believe I still have a fair grasp of the geometry...I just can't replicate it. My issues lie with the amount of stickout of the bit beyond the face of the tool, as well as the stickout of the tool itself. The U3 video documentation implies very little stickout of the bit, but implies tool extension that isn't possible without modification. Any clues you could provide would be very appreciated.