In article Z2Qxf.8$h47.4@trnddc08, says...
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.

You can safely assume that most any VFD you see will be three phase
input, except perhaps for some very small (1/4HP), or low-end units.
The three phase VFDs, in reasonable sizes, will run on single phase if
derated by 1/3 to 1/2.

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.

A VFD is real handy on a vertical mill. Just one example; you can drill
a hole at 2000 RPM, then power tap and reverse at 100 RPM without
touching the belts. For easy speed changes you'll want to use a pot for
speed control rather than the drive's keypad.


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.

I've used quite a few different brands over the years in industrial
settings, and when I have a choice my preference is for Yaskawa drives,
then Mitsubishi. The Magnetek GPDs are good solid older generation
drives that were made by Yaskawa and are quite common on ebay. It'd be
easier to be more specific knowing whether you want a new drive or are
willing to go the ebay or Dealer's Electric route. Automation Direct is
a good source if you want new, but you're limited to Hitachi or their
house brand.

Ned Simmons