single phase converter

Hi all, I just hooked up a used, Snyder brand, Rotary Phase Converter to my newly acquired lathe (more on that soon). It works but makes excessive noise & vibration, especially when running under no load condition. It sounds like its vibrating at 60hz so my thought is its electrical in nature...

I had a request from a good friend, to build a Rotary Phase Converter for his brother's, new (to him) Hardinge lathe. the requirements were straightforward, run a 3 phase machine on 240v single phase supply. the lathe has a 1hp main drive motor , runs a small coolant pump and a 1/4hp variable...