- Joined
- May 15, 2016
- Messages
- 98
I have ground a few twist drills using the four facet method (11 degrees primary relief and 25 degrees secondary relief). Upon testing a 3/8" drill I was pleased with the quality of the hole. The hole had a much better finish than that left by a conventionally sharpened drill except at the breakout end it was not quite as good. The drill required more feed pressure probably due to the point, but it started without the need for a punch mark and did not wander.
I have not tested different angles etc. yet, but, I have two questions before I do go at it: Would a six facet drill having a secondary point angle leave a better finish at the exit end? Would a split point work to advantage here?
I have a tool grinder so I can grind under controlled conditions to get an exact centered grind.
Dick
I have not tested different angles etc. yet, but, I have two questions before I do go at it: Would a six facet drill having a secondary point angle leave a better finish at the exit end? Would a split point work to advantage here?
I have a tool grinder so I can grind under controlled conditions to get an exact centered grind.
Dick