I expect this to work just fine. The motor should not care. The
spindle bearings are designed to cope with the spindle pushing upwards
due to resistance of the material being drilled. So having the head
upside down is nothing truly unusual. Your plan is sound, just keep
going through cheap drill presses if you use them a lot. Joe mentioned
chips getting in the chuck, but you can wrap its business end with
insulation tape or duct tape.

I would make sure, though, to use totally enclosed motors, as a lot of
crud will be falling down. Also watch out for the motor fan clogging
with wood dust.

This whole approach reminds of of WWII production.

i

On 2011-03-10, Tom Gardner w@w wrote:
I have a project that involves drilling four 1/8" holes in a wood block. The block is
7.5" long x 3" wide but has a trapezoid cross section. The volume is sufficient to
automate the job and I need good, consistent accuracy. Two holes go in each
non-parallel face. One thought I had was to jig and clamp the block with one face
parallel to the table and the opposite face would have a 34 degree angle compared to
the first face. Two small cheepie drill presses were mounted upside down under the
table could drill those two holes and two more drill presses would be mounted
right-side up but at a 34 degree angle would drill the two holes on the top face. All
four drill presses would have an air cylinder to extent the quills until a limit
switch is hit. (Joe Autodrill.........STOP laughing!)

Will the drill presses operate OK upside-down?