If steel, a cutting stick on an arc welder....

Wood, a sharp self-feed bit (Up to 4-5/8")
[Linked Image from coastaltool.com]

Concrete, call someone who does core-sawing, and add them to your bid +>20% mark-up. [Linked Image] Cheaper for single holes this way, but not if you nedd 100...


Mark Heller
"Well - I oughta....." -Jackie Gleason