Three Flute Drill Bits

[GeneT45]

MANY MOONS ago, I bought all the drills at a machine shop auction. They go by 64s from 1/4 to 1 1/2 up to a dozen of each size. Got a HUGE number of core drills in this lot most all dull. So, I almost never use them.

Hand sharpening don't work here, at least for me. (I am good at hand sharp 2 flute). Problem is getting all the flutes to cut even. leave one longer and you don't get the results core drills can do.

How do you get these drills sharpened?

Just as a thought exercise (I have nothing on which to experiment) a 4-facet (well, I guess it would be 6-facet) grind seems like it should be do-able. But, since it's all in my mind, I might be missing something.

GsT

 

[Flyinfool]

I only buy 3 flute if need for a special application. Some are core drills but they do make 3 flute drills that can start their own hole and drill through solid material.
3F drills are also good for sheet metal as a 2f will make a trilobular hole the 3F will make a round hole.

 

[Dabbler]

How do you get these drills sharpened?

Serious sharpening setups are required, or you have to use a D bit grinder, both of which are $$$ if you don't need them for other things. Check out Stefan Gotteswinter's youtube channel for his sharpener. That one does 3 flute drills (as an example)

 

[rwdenney]

Stefan Gotteswinter also talked (favorably) about the Motom drill sharpener he bought, which is just a Taiwanese version of the currently popular Chinese drill sharpeners that use ER20 and ER25 collets. Those will only sharpen two-flute drills.

Rick “thinner web” Denney