3phase motor and pulley

Good afternoon all.

I am rebuilding my lathe and have decided to use a 2:1 toothed belt on my 3 phase motor, giving less rpm but more torque as I never use the high rpm. My question is, I have an encoder that is driven from the spindle and not the motor. My VFD is set as per the motor specs (top RPM at 50hz is 2840 rpm). How do I set my HAL file and do I need to?? My max RPM would be about 1420 or so based on the 2:1 reduction.

Thanks

Russell

Yes, the VFD is done through PWM. You kindly helped me many years ago setting this up. The Chinese BOB PWW and GND go to the VFD (Bosch) on GND and A1. I hav ethe 24V fromt the VFD also running through the relay on the 2 BOB's that I am using. I am using two as I need more than 5 inputs. I was hoping to use Mesa but stock is a massive issue. So my HAL was written using Stepconf and I put in there the max speed of 1420 at a full 10v. I assume Linuxcnc will think it is 1420 but the VFD will be running the motor at double that which I assume is OK as the encoder is on the spindle and not motor