71 MKIV
Active member
I concur on the VFD. VFD's are better than rotary converters which are better than static converters.
Weird fact of the day. Any 3 phase motor can be used as a rotary converter. Hook up your two hots to two of the inputs, and use a rope, ala old lawn mower, to get it spinning. The third phase is induced into the third connection of the motor. Your converter just needs to be bigger than the motor you are running. IE, a 5 HP converter will comfortably run a 3 HP or smaller. The armature of your converter needs to be big enough to have the mass so as to not stall trying to start your machine.
edit: the only difference between a rotary converter and a regular motor is the converter is wound so it starts on only two phases.
I didn't see any CAD machines and I'm not sure how much speed control Thomas needs. A high quality rotary with some capacitive filtering might be a nice compromise between cost and use.
FWIW
YMMV
Steve
AKA 71 MKIV
Weird fact of the day. Any 3 phase motor can be used as a rotary converter. Hook up your two hots to two of the inputs, and use a rope, ala old lawn mower, to get it spinning. The third phase is induced into the third connection of the motor. Your converter just needs to be bigger than the motor you are running. IE, a 5 HP converter will comfortably run a 3 HP or smaller. The armature of your converter needs to be big enough to have the mass so as to not stall trying to start your machine.
edit: the only difference between a rotary converter and a regular motor is the converter is wound so it starts on only two phases.
I didn't see any CAD machines and I'm not sure how much speed control Thomas needs. A high quality rotary with some capacitive filtering might be a nice compromise between cost and use.
FWIW
YMMV
Steve
AKA 71 MKIV
Last edited:
We are in the process of moving across the country, buying a house and building a shop (whose process has been heavily influenced by stumbling across YOUR thread and thus GJ).
only you can determine, just be careful what you say.

While we may get ice and snow once in a while those brutal temps don't happen down here.