My motor burned up this week, so I figure it's time for an upgrade and a belt drive. I have a couple of those huge 3.8HP DC treadmill motors and a KBMM-225D-KB for the drive (plus heatsink, and all that other stuff), but I have also this 2.2kw (3HP) spindle motor and VFD (like this Sanven Water-cooled Spindle Motor 2.2kw Inverter Vfd 2.2kw Variable Frequency Drive 8000-24000 R/min, More Precise, Collet: Er20(4mm, 6mm, 8mm, 12mm, 12.7mm) - Power Spindle Sanders - Amazon.com).

I have been planning to run the spindle motor on the side of the head, but maybe it would also work as a drive motor and mount a pulley to it instead. The spindle is rated at 24kRPM, and I have no idea what RPM the DC motors run up to.

The two DC motors are a bit rough, and are going to take some work to get running (both took damage in shipping). The spindle motor is quite a bit lighter, so that would be nice. I have no idea if the spindle would work well as a driving motor for the actual spindle in the mill. Any thoughts?

Left to right is two 3.8HP DC motors (I have a controller for it too), the spindle motor, and the stock G0704 motor on the right.
Attachment 243416