I am looking at making many 1.5" holes with a countersink 1/2" deep in
large steel plate. The depth tolerance of the countersink is
critical. The plate varies in thickness and can be slightly bowed.
How do I control the depth of the countersink on a CNC machine? I
can't just go to the same Z position every time. The plate is too big
to probe every location and correct for depth, or at least I don't
want to take the time to do it. I found a spring loaded tool on the
web but it is too small.

Any ideas or tools I don't know about????

Thanks in advance. Any constructive replies are appreciated.