AB (Allen Bradly) GE, Westinghouse , Cuttler Hammer, Square D, Siemens, and hundreds of offshore companies all make VFD's ( variable frequency drives) Their products can be found on line or in local electrical wholesale houses. None are inexpensive. The picture is a single phase capacitor start open drip proof motor. The oval thing on top of the motor is the capacitor. Some single phase motors are called split phase motors and don't have a capacitor but do have a start winding that will fail at reduced speed because the centrifical switch inside the motor closes and puts power to the winding which is only susposed to be powered for an instant at a normal start. There are other types of single phase motors such as shaded pole, consequent pole like in a fan motor but they are under powered and will not run a drill press. iF WE REALLY WANT TO GO BACK TO THE OLD DAYS, I have a repulsion start induction run motor on an old machine tool that is older than me but works better than I do at 70 yrs, LOL.