Options for replacement lathe spindle motor

[Doddy]

Ah, Muzzer, ask why though. It was to have an accuracy in positional control on the spindle position for threading. Oversized to avoid pulleys - yup, that's the rationale behind replacing a 350W motor with a 2kW motor. The servo is driver by step/dir exactly for positional control, via a 1:1 pulley direct to the spindle.

Cost, actually, not substantially different to the 3 phase 4 pole motor with VFD that I replaced with less than 12 months on it, to be honest. And I don't have the lag through the VFD for spindle speed.

Oh, and another reason - because it's an interesting experiment if nothing else.

[pippin88]

Servos have very good speed control. AC servos pack a huge amount of power into their small size.

Downsides of servos
Need some tuning - pretty easy with a decent brand
Cost - may or may not be more than a non servo setup depending on brands and a bunch of factors.

[Lotus23C]

Hey there, how did you get on with the AC servo spindle on the myford?
I am considering it on a BUD Boxford conversion.

[Doddy]

It's fine - I've no problem with the servo as a solution. It did require, of course, a special-to-type cradle to mount it on the ML7 but nothing that 10 minutes with a TIG, and 20 minutes with a grinder can't fix.