John,

If you are talking about enlarging an existing hole, it will work fine.
You may have to make multiple passes, re-setting the bit after each
pass. You will have to measure very carefully on the last few passes
if you need any real accuracy. All of which will take time.

Accuracy is not a big deal, which makes the discovery of an appropriate
hole saw reasonably likely. Hole saws are getting fairly good reviews
in this thread, which increases my confidence in them.


The boring head, of course, will be a lot faster as you will just crank
out the slide after each pass.

Dumb question: when you say a "pass", are you referring to: (1) set the
bar at a given radius; (2) quill down to contact; (3) slow feed until
breakthrough? Is the bar parallel or perpendicular to the spindle?
Does it matter?


If you don't have the central hole to start with, it's a lot more
difficult. You could grind up a trepanning cutter for a fly cutter
head, but it would be a lot of work to get the edges right for both
inside and outside cutting and it would only work for very thin stuff.
In the boring head you can hold the bit end on to the work, and can
therefore grind it a lot more effectively.

The stock is thin, so I have that going for me. I'll try to do some
reading on trepanning and then take another crack at this and Harold's
answer. Correct me if I'm wrong, but I think you guys are saying pretty
much the same thing.

Thanks,

Bill