Thread: Drill grinding weirdness

Originally Posted by veitnamcam

That drill has a thicker center section and a different flute profile ground into it, the center section generally gets thicker as a drill gets shorter or some drills are just designed stronger in that center part (most cobalt for example)
If you are going to sharpen it in your jig you will have to rotate your start point on both sides so that the non cutting center line diverges further away from 90deg to the cutting faces.....or as above other posts...some jig type grinders will do a center point tho.

Or simplest of all whack a 3-6mm pilot threw first then the center doesnt matter

what he and gundoc said.
First test at trade school was sharpen a drill to cut nor more than 0.1 of its size. as such I look with disdain on drill sharpening gadgets.
I consider myself relatively proficient at sharpening drills without guides at least up to maybe 5/8". Once they get bigger and the hole size is important then the guide and ruler come out
A big drill can cut way oversize if you get it wrong

Originally Posted by csmiffy

what he and gundoc said.
First test at trade school was sharpen a drill to cut nor more than 0.1 of its size. as such I look with disdain on drill sharpening gadgets.
I consider myself relatively proficient at sharpening drills without guides at least up to maybe 5/8". Once they get bigger and the hole size is important then the guide and ruler come out
A big drill can cut way oversize if you get it wrong

Remember that well. Was given a flattened off drill and a plate with two ground sides. Had to mark out and drill the hole to correct size and within spec to sides of plate. Best way to learn.