easiest way to control a potentiometer spindle with mesa 7i96s/7i92tm/7i85s?

I am trying to control my sherline lathe spindle motor which is typically controlled by a potentiometer that directly runs mains voltages. I have been reading older threads and have been trying to better understand my options on how to control this:

It seems I would need to generate a PWM signal from one of my mesa boards and use an isolated pwm to analog converting board like the SPINX1 - is that correct? Are there any other easier ways?


Also - how can I generate the PWM signal? I have read I can flash my mesa 7i96s with a specific firmware to give pwm on steppgen 4 - my concern with this is that I spent forever geting everything up and running with this lathe, and am worried I will break something

I also have the mesa 7i85s (and 7i92TM) which I read can generate pwm. I am not the most savvy with this stuff (hence it took me forever to wire up a 2 axis lathe) - so I am looking for advice on the simplest (and safest) way to accomplish replacing the potentiometer control on my sherline lathe spindle for linuxcnc control

Please help and thank you so much!

A 7I96S has this built in (TB2 pins 22..24)
This is supported by all 7I96S firmware