the old grind
Elite Member
- Joined
- Jul 21, 2012
- Messages
- 4,412
- Location
- Mid-Michigan
- Tractor
- NH T-1520 HST, NH TC33DA HST, Case DX26 HST, .Terramite T5C, . NH L785
Several, not just router bits. Just gotta know how. Use a 12v9 wheel to face the flutes. Be sure you set up for positive vs negative rake. Rotate the cutter vs moving the wheel for further passes, to preserve rake angle. (5-7 deg pos) This will remove any friction coating right away, from where it's needed in the flute. (so not removed from a twist drill when end-grinding)
Don't worry about the OD, just bring the corners of each step up sharp. It's all about your fixtures/tool holders and anges or don't go to much trouble. Unlike twist drills we don't need to take the same amt of stock from each side to drill to size. The huge margins guide centering and what coating is lost there is usually due to wobbling in a hurry to finish a hole. It wouldn't happen much if used in a DP.
Don't worry about the OD, just bring the corners of each step up sharp. It's all about your fixtures/tool holders and anges or don't go to much trouble. Unlike twist drills we don't need to take the same amt of stock from each side to drill to size. The huge margins guide centering and what coating is lost there is usually due to wobbling in a hurry to finish a hole. It wouldn't happen much if used in a DP.