Wow. They sure have come a long ways with servo motors.
Now they are programmable, brushless and with software are now smart.
Check this one out - http://www.ebay.com/itm/Enduro-Pro-SM650-1Energy-Saving-Industrial-Sewing-machine-Servo-Motor-800-WATTS-/230979320037?pt=BI_Sewing_Machines&hash=item35c770b8e5 (http://www.ebay.com/itm/Enduro-Pro-SM650-1Energy-Saving-Industrial-Sewing-machine-Servo-Motor-800-WATTS-/230979320037?pt=BI_Sewing_Machines&hash=item35c770b8e5)
I love my servo and own two identical units. Both have a simple dial switch on the front to change speeds. Never seen them like this before where it can sense power surges and can be programmed to different speeds going forward and in reverse.
Chris