I'm trying to help a friend who has a CNC machine.

He wants to use the Mach3 closed loop speed control to control the speed of his router.

I know very little about Mach3 - I'm giving him advice on the electronics issues.

Could someone please point me to a description of what type of feedback signal the Mach3 PWM speed control needs.

I assume it is pulses derived from an optical shaft speed detector.

Also, how is it connected to the computer?

I have a copy of Mach3Mill_Install_Config.pdf but it lacks detail on the speed control function.

Any advice will be appreciated.

Afraid I know nothing about the PWM type speed control in Mach as I use Step/Dir with Servos. Having said that the only feedback to Mach for any spindle speed monitoring is a single pulse per rev that you input via the Index input.
Hood

Thanks Hood,
That gives me a clue as to what to look for.