I just came across a old Stanley 1/2 hp, cast iron bench grinder. It didn't have a cord on it, but was marked 3 phase 440 volt. I wired it up and tried it on my rotary phase converter, which is of course 220v. I ran it for just a few seconds, maybe a minute. It started and ran about 3000 rpm at first and then started pulling down so shut it off. upon disassembly found a dry dragging bearing which might account for the slowing down issue, but I suspect the voltage issue is the real problem. There are only 3 leads coming from field windings so I assume it is 440 only. It is a neat old grinder and I would like to salvage it, but don't know of an option,except ask you guys. any ideas?