I put a VFD on my X-Carve and now have no use for the SuperPID or DW611 (modified for feedback) Setup worked great, I used a pot to vary speed but there are topics on the Forum that describe how to integrate it into the X-Controller. comes with the precision 1/8 collet nut and wrench. $250 firm.
What is a VFD?
Variable Frequency Drive, I had one sitting around and it integrates into X-Carve a little easier, that and I am building a more robust CNC Router.
Variable Frequency Drive, the voltage regulator that power (rpm governor and direction) of a dedicated AC spindle.
Think ESC (VFD) and brushless motor (spindle) for RC cars/planes/drones.
Basically a industry standard for CNC applications.