On Sun, 30 Sep 2007 19:45:31 -0500, Jon Elson wrote:
monkers wrote:
Could someone give me a crash course in VFD for a 1960 J Bport mill?
My primary concern is for the variable speed, I have a rotary phase
conv. but would like to know more about VFD. Can an average guy like
me hook it up? Thanks,
Sure. If you don't have variable speed now, that must mean you
have a 1J, with the 4-step pulleys. That usually has a 1 Hp
motor. I have been running a 1J myself with a 1 Hp VFD by
Magnetek, and have been using it since 2000 or earlier with no
trouble. I get variable speed, soft start and dynamic braking.

I run a Bridgeport on a VFD also.

I would also mention reversal.

Most people recommend if you run a 3-phase only VFD on single
phase, that you derate the HP of the VFD, so use a 1.5 or 2 HP
rated VFD. Some VFDs in the 1 HP size are rated for operation
on single-phase, but they generally cost more. Generally, the
smaller VFDs that are rated for 3-phase only don't have circuits
to detect single phase, so they will won't complain about a
single-phase supply.

Make sure the VFD you get is for 240 V operation, not 480! The
480 V units go real cheap on eBay as they are not useful for
home shops. If you get one with a manual, it will save you a
LOT of hassle.

Manuals for most of the drives can be easily found on the
net. (Toshiba, Allen Bradley, Delta, Megnetek/Saftronics, Mitsubishi,
etc).

These things are pretty complicated, without the manual, you are
deep in the swamp. Some of the cheap ones only have pre-programmed
speeds, you want one that will accept a speed control pot. I put
the speed pot on the machine, the VFD is on the wall.

The drives category on eBay is a real nuthouse. I regularly buy badly
described VFDs, test them and resell for 4-5x the price. It pays to
look for things that are poorly described, poorly photographed,
etc. That means that there is a learning curve involved in figuring
out model numbers, etc, but it is not that difficult.

i