Drilling big hole through steel plate

[Geoff Winnington-Ball (RIP)]

Originally posted by Tony Smith
A 2 pdr AT gun will produce some neat holes, but they are only 40mm, or a little over 1 1/2in.

Not a Circular Saw , but a HOLE SAW is what you require. (Picture source, catalog p2246)

Picky-picky! : Yes, a HOLE SAW (it was late when I typed that). They will work on mild steel, but only if used at slow speed and with plenty of CUTTING OIL. A drill press is ideal, but if the piece of steel is too large, a good variable-speed 1/2" hand drill with lots of torque will do it. Those cylindrical tapered bits will work as well, but wear out much more quickly.