I bought a 3/4" bit from Lowes on Tuesday, and that night I took a grinder to it - actually three grinders and a lathe.
I chucked it in the lathe and started it spinning at 1240 RPM and used my 4-1/2" angle grinder to bring the tip down to the shape I want - a nice gentle slope with no shoulder. That took about 5 minutes.
Now, the hard part. Because of the way drill bits cut, and the method I used to shape the bit, the cutting edges barely made contact with the wood. I had to cut down the steel behind the cutting edges with the bench grinder so that the bit could make contact with the cutting edge rather than the face of the bit behind the cutting edge. This took much longer, about 20 minutes.
After that, I fine-tuned the cutting edge and smoothed out the divots and flat parts in the face behind the cuting edge with a die grinder. This took about 15 minutes.
Then after I got the bit so that it would cut, and the metal was smoothed out and looking okay, I got out the diamond stones and put a nice hone on the edge. This took for-fricking-ever.
Got my first chance to try it out tonight, and boy-howdy! Some days, I impress myself. The thing cuts like a dream, doesn't chatter, doesn't leave a chamber that requires lots of sanding, and is stable as all get-out. It cuts a hole where I tell to, and noplace else.
Of course, you shouldn't try this at home kids. I'm what you call "a professional". Well, nutcase might be closer to the truth....
