In article , DoN. Nichols says...

I would suggest that for machines which have only steps in their
speed selection (e.g. gears or belts and step pulleys), the VFD is
preferred, while for those with variable speed pulleys, and for running
multiple machines at a minimum initial investment, a home-built rotary
converter (built around a larger three-phase motor, some capacitors, and
some voltage-sensitive relays) would be the better choice.

At the face of it this would seem to be the case,
but the really odd part is, folks who have some
machines like the monarch 10EE, or the lathe with
the variable speed drive that everyone dislikes
(I think this is either a rockwell, or a delta,
or maybe it was both) seem to say, the varispeed
drive is a major pain, and they always retrofit
with a VFD. But the folks with step belt machines
like southbend or the older hardinges, seem to
get along fine with step belts.

Where the VFD really shines though, IMO is in a
drill press. Just *so* handy for getting the right
speed.

Jim

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