I'm in a unique situation. I have 3phase going to my shop. Works great.
However, I would like a VFD to speed up my 500 rpm maximum LeBlonde 13"
lathe (1949 vintage). Couple of questions:
1) I can't seem to distinguish between single phase and three phase INPUT
on most of the ebay items. Seems like most customers want single phase
input.
2) In addition to my lathe, I also own a large Tree Mill, Brown & Sharpe #2
surface grinder, 2 large bench grinders, all 3 phase. Is there any reason I
would want speed control on the above machinery? The mill goes to 3000±
rpm.

Anybody that is using 3phase input simply to control speed, I would like to
hear what brand and model you are using. Having that information, I can
shop wisely.

Thanks,
Ivan Vegvary