Schaublin 125-CNC retrofit.

Good point. Didn't think of that. Although given the that a variator is a pretty imprecise system, if you pulse the variator speed change motor at a fast enough rate, that may not even show up on the surface finish.

please consider, this is a 4/6 pol Motor from the 70s. It will have insul class B, if you have very much luck evtl. D. But it won't be designed for vfd use. So max usable range on an vfd should be >40 <60 hz. Smelling motor coils would be the smallest problem, an vfds IGBT modul which get high voltage rollovers under load, will become a very nice pyro effect.

this is a better explanation, as if i would try to write it english.

library.e.abb.com/public/fec1a7b62d27335...6a0fd/voltstress.pdf

look at page 15. thermal stress is not the big problem in our hobby use, but the (sideshow)voltage effects from an pwm drive are the problems.

please consider, this is a 4/6 pol Motor from the 70s. It will have insul class B, if you have very much luck evtl. D. But it won't be designed for vfd use.

Yes, I tried running the spindle motor on my aciera mill from the 70s on a VFD, it worked only for a couple of weeks before the motor gave out.

Wondering if those using a VFD in their home shop have used a AM radio to get a feel about the amount of radiated electrical noise emitted ?
VFDs made in the 1990s could stop the neighbours listening to " The Rush Limbaugh Show" . I thought that was a design feature ----
Just curious if the newer VFD s affect AM radio reception .

Mark
Noticed that Jaro ( 2-speed spindle configuration ) has posted his new working HAL & INI files for his Schaublin Mill. Think his mill uses a 2 speed transmission .
Might look at how he used andypugh's code .

I have been running the original motors on my 1964 Holbrook lathe and (probably) 1970s Harrison milling machine on VFDs for many years now with no issues. Possibly Brook Motors used a different insulation to the Aciera supplier?

I know there are people out there who have been running motors with isolation class B on VFD's for years. I guess what I'm trying to say is that using a VFD on motors with isolation class lower than F can indeed destroy the motor. So really it comes down to how badly it's going to hurt to replace that motor.

Wondering if those using a VFD in their home shop have used a AM radio to get a feel about the amount of radiated electrical noise emitted ?

VFD's are noisy devices that is why the manuals tell us to follow proper grounding and filtering practice. Usually interference comes from installations that have been poorly executed. The most annoying problem I have is that the filters sometimes trigger the RCD.