[CJV]

Thanks all for the constructive advice.

Guess there had to be a downside. Yes, the aluminum ground off like butter, but interestingly did not clog the grinder wheel. I could see why that would be a discouraged practice, especially in a shop.

The dremel bit, however, did clog up right away. I switched to the flex extender and spun it down way slow, using a large cutoff wheel to finish the inside of the exits.

Anyway, perhaps the better approach might have been a diamond cutting wheel on an 18V circular w/ depth control. Recall that the key was that the mast is up, and lines, wires are alive inside.

Thanks again for the contributions.