It sounds as if what you REALLY want is an indication of the actual speed of rotation of the spindle to compare with the speed indicated on the VFD. Muzzer, you've reminded me of my old induction motor principles training. If I remember rightly a standard induction motor is designed to run at about 95% of the field rotation speed at it's rated power. Aren't these spindles permanent magnet rotors?

m_c, Sounds as if the fixed torque value in HSMA is not unreasonable but I should be setting the VFD to display motor current rather than rpm.

Thanks for the help.

Kit