Rigid Tapping on my PM-25

[ronster]

I'm wanting to do rigid tapping on my Acorn equipped PM-25. I have an 2000 per encoder to install and I am presently using the KBSI-240 for my spindle control, which works fairly well for most of my milling.
My confusion surfaces when I consider the alternatives if there are any to do rigid tapping on this machine. I've been told to just settle for standard tapping without motor upgrade to AC and a VDF. Ideas?

Thanks for help insight.

[cncsnw]

You do not need "exact" RPM control to do rigid tapping. Anything within 10% or so it close enough.

What kind of motor is your spindle motor?

I thought the KBSI-240 was a signal isolator (used with another drive, often also from KB Electronics). Are you sure you don't have another device powering your spindle motor?

[ronster]

Thank for the response. Yes, the KBSI is a signal isolator. I have a stock DC 750w motor and the KBSI-240 takes power from the Acorn 10v output, which is tweaked from 0vdc to 5vdc. The Acorn relays are wired for the forward and reverse direction.