How thick is it? What is the diameter? I’m sure it can be done but it will either require a lot of work or a machine that makeict doesn’t have. The plasma table might do it, but it depends on the thickness.
The plasma cutter will cutter will do 3/4+ mild steel. maybe an inch. Edge start so you would need to pre drill a hole… The cnc is in a questionable state. There are some intermittent faults. I am not sure how you would align it anyway without sacrificing a sheet of metal to cut a matching circle and dropping the cover in the resulting hole.
The hand torch should work. I have never hand cut with it so I can’t say what it would be like.
I would look on the wiki to verify cut speeds and thickness. I thought it is a hypertherm 65.
Doing some test cuts in the outer ring would let you know what it would be like. A lasy Susan setup with a clamp on the torch head should produce a nice circle. You would just need to match the speed of cut.
A little off topic but I saw a YouTube video where folks are inking manhole covers then pressing shirts against the covers. Like a big rubber stamp. Then selling the shirts. Most manhole covers have a local twist that made the printed shirts popular. So, before you cut it, try printing a shirt!
Seems like it would be better to scan it, route it in reverse than use that as a stamp. Or stamp one shirt then turn that into a screen for printing, where it could be oriented right. Maybe it loses its appeal then. I dunno.
How thick is the plate in the area where you want to cut? I see it looks like it is thicker in the middle than the edge you measured. Cast often has webbing to make it stronger. Are the webs directly under where you want to cut it?
It skipped my mind that it extended behind the lip when I originally posted the images with rough dimensions.
The part that extrudes from the back is about three inches and has a webbed pattern. No picture of the back because I couldn’t take a picture holding it away from the wall. I think it weighs about 200 pounds.