Drill bits

RWasiczko · Jan 6, 2020

I recently received a large collection of twist drills from the wife of a deceased machinist.
Several of the bits have two flats on the shank, at the end of the shank, 180 degrees apart.
I have done some research, and see that some bits have three flats on the shank to get a more secure grip in the chuck
are the two flats along the same lines to get a more secure grip?
or are they for some other purpose?
Thanks
Bob

sfriedberg · Jan 6, 2020

Assuming you're not talking about little bits for Yankee screwdrivers/drills, I have a vague recollection of a production drilling chuck, probably in the automotive sector, that drove the drill from two flats. The application was stone stupid basic drilling, but the tooling style was very niche. IIRC, those two-flat drills could be driven from an ordinary 3-jawed drill chuck without too many issues. In the worst case, chop the flattened end off the drill and chuck on the round shank.

L Vanice · Jan 6, 2020

Specifically, the bits with two flats are for use in Morse taper adapters, which have bores specific to the bit size. They are called automotive tanged shank bits. They are used in production machinery where the Morse taper shank is superior to a drill chuck and the bit plus adapter is less costly than bits with integral Morse taper shanks. Once the adapter is removed from the driving spindle, a dull bit can be removed by hand and a fresh bit pushed into the adapter. When the adapter and bit are pressed into the spindle, the adapter grips the bit tightly.

Larry

sfriedberg · Jan 7, 2020

Thank you for clearing the fog out of my memory, Larry.

RWasiczko · Jan 7, 2020

WOW !!!
Thank You very much
the collective knowledge on this forum is amazing
Thank You
Bob

Search

Largest Manufacturing Technology Community on the Web

Search

Drill bits

RWasiczko

Plastic

sfriedberg

Diamond

L Vanice

Diamond

sfriedberg

Diamond

RWasiczko

Plastic

Similar threads