Keith,
Do you have your mind made up on the rotary converter deal? Here are my thoughts. I have a a Bridgeport clone that I ran off of a static converter and it worked flawlessly. I have a 5 HP Unisaw running off of a static unit and it works flawlessly.
I have built rotary units with capacitors, a magnetic starter and idler motor. I am sure you have researched all this online. Phase-A-Matic is a pioneer in the field of static and rotary converts and I have included a link to them.
Having blown all this smoke I will say this. Switch mental gears and think 'AC Inverter". The price is pretty compararble and the benefits are bountiful. You get tons of options, the most used on a Bridgeport or lathe being infinite variable speed, clear up to 400 HZ. You get acceleration and deceleration ramps and braking too. Instant reversing which is 'way cool' when using the mill as a tapping machine.
On a lathe, you don't have to change gears to go from 200 RPM clear up to 2000 RPM, and as soon as you hit the OFF switch, the headstock comes to a stop in nanoseconds if you have it setup that way.
Each machine tool would have its own inverter and they have built in motor protection. The motor will see a modified three phase so you don't have to derate like you would with a phase converter.
E-bay sells lots of these inverters (Drives Warehouse). I have found Hitachi to be one of the most reasonable and easy to program. There are tons of used ones too. Most will take single phase input even though they don't advertise as such. Any single phase input will result in a three phase output.
Look at the prices and decide. If you are set on a phase converter, I would weigh the static against the rotary. There aren't going to be many times when you are running two machines at once. I'm not sure on this, but a welder, being a transformer may not be the perfect candidate for any type of third leg 'fake' generation. The motor windings are what help to create the image of a third leg and this isn't the case with a transformer.
http://www.phase-a-matic.com/PDF/RPL-2009-C.pdfStuart
