Marty
Drill your 7/8 hole with a regular drill to the proper depth. Then
uses a reground 7/8 drill with flat bottom. It will need a relief gash
in the center to enable it to cut properly and I would put a small
radius on the corners of the drill to prevent chipping.
at this url the second pic from the bopttom shows a bottom drill
http://www.rushmachinery.com/prod01.htm

Marty wrote:
I have to drill a number of flat bottom holes, 7/8" diameter and 1/10"
(.1") deep in some 2/10" (.2") thick aluminum. Is there a source for
flat bottom drill bits of this size that will fit in the 1/2" drill
chuck that's on my drill press? If there are no bits of this size with
a turned down 1/2" shank, can an adapter be purchased to go from the
7/8" bit to the 1/2" chuck? Thanks for any help. Marty


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James P Crombie

Summerside Machinist
Prince Edward Island Amateur Astronomer
Canada 3D Designer

E-mail
Astronomy webpage http://www.jamescrombie.com
Rhinoceros 3D webpage http://www.jamescrombie.com/rhino/
Mirror Grinder page http://www.jamescrombie.com/pics/
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