Annular cutters?

Boring holes in structural steel with a mag drill.

I use them all the time for cutting large holes on the mill before switching to a boring head. They're also the best way to pop the 22mm or 30mm holes for oiltight switches in a control panel or NEMA box, if you can fit the work on a Bridgeport.

I've not tried that but I have used one with a guide to remove the weld seam inside pipe, also they seem to work well for scalloping one pipe to fit another. For the latter use I've just held them in a 3/4" collet in a Bridgeport mill.

Cool. Thanks to everyone. I'll have to give them a try.

Best regards, Spehro Pefhany