bought the inverter to run the mill, which is 380v three phase, it turned up and the documentation said it could run 4 separate motors (one at a time, obvs). The mill has a 2 speed dahlander motor, so effectively 2 motors, and the lathe also has a 2 speed dahlander motor, so 2 more motors, 220v three phase for the lathe, that makes 4. So a bit of electrotech later, which involved gutting the rotary phase converter and all of the lathe's control circuitry and we get something that looks like this:
All fine and dandy except that the inverter can, in fact, only be configured for 2 motors, and that as the lathe is 220v, under load it pulls more current than the inverter can supply even though the motor is less powerful than the 2.2kW it's supposed to be able to drive. Bah!