After posting the message about my exploding cap and subsequent 3Ph +VFD conversion, another thought occurred to me: Both my original 1single phase 1HP, 120V lathe motor and the 2HP, 240V mill motor used the same capacitors --150uF starting cap and 30uF run cap. This suggests two things: one, that if the start winding impedance is as low as I think it is, the start current would be 2X as much on 240V as on 120V. Since the 1HP lathe motor could be hooked up for either 120V or 240V, I would think the centrifugal switch would be much more abused at the higher voltage and current. In any case, the starting circuit is a weak link. Secondly, the phase shifted run current would be inversely proportional to the cap value, or 1/5 the starting cap current. The 3ph motor is superior because all three windings are equivalent and all contribute to establishing the direction of rotation. And, like I said, no switches, no capacitors....
Craig
So, bare with me here. Electricity and related are not my strong point. But I gather you are suggesting that if I rewire the motor for 110V, it may be easier on the start winding? I'm not sure that that is easily done on my mill as the whole control box, including the power feed and Z axis motor are 220V......
Also, It would have been my assumption that 220V would be less stress on the motor as it requires lees amps to achieve the same power output.
And another also. That is an extremely slick conversion you did. Do you happen to remember what the shaft size on your motor was? I think mine is metric, I want to say it's 25 mm, or something very close to that.
Could you relay the information about that 3ph motor you have on you mill that is pertinent? I would be very interested in switching it over to 3ph with a VFD.