Thanks to everyone who responded to my request for info on drilling some
flat bottom holes in aluminum. If I can't track down a flat bottom
drill bit that meets my specs, I'll just try taking several standard
7/8" bits (with turned-down shanks) to a machine shop and see what they
can do to flatten the ends. Next, I'll try it out on some scrap and see
what happens. If that doesn't work, I'll just drill all the simple
holes myself (42 holes in each of about twenty 11" x 19" aluminum
plates), and then take the batch to a machine shop and let them do the
two bottom holes that are on each plate. Thanks again. Marty