Denford Novamill Mach3 conversion

**JohnHaine** · 18-10-2014

Ok, I found the circuit, it's on the Mach discussion forum called something like "PWM spindle circuit advice" by superagurk. I'm sure one could make something simpler though, but I haven't yet tackled the job of controlling my spindle from Mach.

**EddyCurrent** · 18-10-2014

I should have downloaded the drive manual first. I can see that there is a 400i version that is isolated. Pretty naff I would say, why make a drive like that ? are we saying the potentiometer is at mains voltage ? are they even designed for that ? I never expected the chassis to be live and the symbols for 'common' show they are connected to the chassis.
It just shows how you can be lead astray when you are used to working on proper industrial equipment.

Sorry for giving you duff information Miller, I'll remember to read the proper manual first in future instead of relying on gear I've worked on in the past.

**JohnHaine** · 18-10-2014

Lots of pots designed for mains isolation, that's how all TVs used to be. There is nothing wrong with designing a drive like this, as long as the speed control is manual with an isolated pot. My KB drive is industrial, they have a whole range of them.

Miller, important to note that the circuit in the Mach forum has to have its own mains power supply to maintain isolation. The trouble is that it needs a supply above 10 volts to get 10 v max output.