Ignoramus10035 wrote:
eBay is full of those:

http://shop.ebay.com/?_nkw=%22micro+drill%22+carbide

or similar tiny carbide end mills.

My question is how usable are they on a hobby sized CNC machine like
my Bridgeport Interact, with slow top speed. Is using them totally out
of question, or just frustrating, or perhaps they are handly for small
work?

Sure you can use these on your mill. Feed will have to be appropriate
for the spindle
RPM, something like .0001" per revolution, for the smallest ones. That
makes for
pretty slow going, but if you are only doing a few special holes in
something, it will
work fine. These are really designed for drilling composites, but you
can drill copper,
brass and aluminum just fine. Steel will require even more care. If
the point of the drill
enters even a hair off center, the drill will break.

Jon