I wired the VFD to the lathe. Not in the best way yet, but enough to
experiment. Toshiba VF-A3 3.7 kW VFD, similar to what I sold to Pete
C, only bigger and with cracked top cover. (I have more for sale, 2.2
and 3.7 kW)

Here's one very encouraging piece of news (related to what Karl said):
switching of the speed selector lever while the motor is running does
not destroy the drive. It simply trips on a overvoltage error and lets
the lathe coast to stop.

I am very satisfied with this behavior. It is as perfect as it gets.

The drive can easily accelerate the lathe, even at the highest
speed setting, etc.

Right now it trips when I press OFF, no doubt due to too ambitious
braking that is the default setting right now.

What I need to do is:

1) A lot of settings need to be set such as no braking, fixed
frequency (60 Hz), one-two second acceleration, etc etc.

2) Wire it properly to turn on with the limit switch operated by lathe
ON/OFF/BRAKE lever

3) Place the VFD deep inside the lathe cabinet so that it would not be
a hazard or distraction. There is no need to access the drive once it
is set up. So I will put it away. This will be a single phase lathe
that would be operated with its original control and no weird wiring
outside.

The ONLY thing that I may allow to be visible outside is the FAULT
indicator shown by a LED bulb. Maybe a FAULT with RESET
pushbutton. That's all. I do not want switches, potentiometers, none
of that stuff is necessary.

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