Run caps and their application

I have a 10 HP phase converter that I have been running for a couple of years to power a Bridgeport and a South Bend 16" quite successfully. I recently acquired a FG 10,000 Van Norman flywheel grinder. This machine is 10 HP on the grinder head with a magnetic starter. When I try to start it with the start button the magnetic chatters (for lack of a better term) won't kick in and won't start the motor. It kicked the motor so hard once the grinder stone unscrewed and fell off. I have never checked the voltages on the converter and never used any run caps. I am also finding the grinder motor pulls 17.8 amps on the L1 and L2 hot legs but only 5 amps on the made leg L3. I can push in on the magnetic and the motor starts right up but when it is under load (3 or 4 flywheels) it gets pretty hot. I figure the made leg is not producing enough voltage and the motor is single phasing. How would I add run caps and what size should I look for to fix this.

TIA.

I'd start by checking the three legs with a meter.

Swap the coil leads to a different phase. I had the same problem with my RPC.

Tom

Any switching or control portions of the machine should be run on the service lines,the generated leg should not be used for those functions.

OK, this morning I switched the 3 legs around so I could get a hot leg to the starter and it works great now. I still need to know how the run caps should be hooked and approx. what size I need to equal out the legs so the amp draw will be the same if possible. This siteis great, I would have never been able to build the RPC or get what I have working without it.

Thanks for the suggestions.