On 9 Sep 2003 06:56:39 -0700, (Dan Thomas)
wrote:

You want a slot drill, not an end mill. Slot drills look like endmills
but have one or two teeth that extend to the centre. They're used for
cutting keyways in shafts, or slots in flat stock; they'll drill
through vertically then can be run sideways like an endmill.
But it will take a really good, heavy drill press to keep it from
walking around. Better to use it to clean out and bottom a
previously-drilled, slightly undersize hole.
Dan
If this hasn't been suggested then you could try the following: Grind
a drill flat on the end that's the same size as the hole. This can be
done by grinding, by hand, the end of the drill square. Then, also by
hand, grind each flute so there is relief back from the cutting edge,
Use a wheel with sharp corners. When close to the edge and center
finish with a hand stone. Drill hole with regular drill and remove
point with flat ground drill. I do this from time to time. I am always
grabbing the flat bottom drill out of the drawer even though there's a
bunch of regular drill in there.
ERS