Hey David,
No, the one has nothing to do with the other. However there are many reasons to avoid a 120 V spindle, because at same power (kW), half the voltage (Volts) means double the current (Ampères), especially if you want it to have more than 0.75 kW. There is a search function in this forum.
The relay in the Elite power supply for North and Latin America and Japan, which means, the 120 V version, can only switch a 120 V 10 A shop vacuum. If you have a serious dust collection system, you will have to implement another solution with a relay to let the CNC controller dust collection automatically go on and off by the g-code program. There is a search function in this forum.
No.
The Onefinity Elite Power Supply. Left: Version for North and Central America and Japan, right: Version for the rest of the world.
A spindle is a three-phase frequency-controlled induction motor and is always driven by a VFD. A VFD is an inverter that first transforms the input AC current into DC current, stores it in a big capacitor, and then, by switching on and off six IGBTs, creates the three-phase current needed by the spindle. A VFD can be controlled by the CNC controller via a spindle control cable (wiring).
In the g-code program, the M3 (start spindle) command sends the control signal to the VFD for the RUN command, and M5 (stop spindle) command sends the control signal for STOP to the VFD.
Important note: A spindle is NEVER switched on and off by a switch or relay, but only by sending the RUN/STOP commands to the VFD. Otherwise you may destroy both the spindle and/or the VFD.
Similarly, via the same spindle control cable, an analog control voltage is output by the CNC controller that sends the speed for the spindle to the VFD. The speed is set with g-code too, with the S command.
Note: This is valid for the Onefinity Elite Series with the MASSO G3 CNC controller, which does not support Modbus communication. On other CNC controllers, like the buildbotics-derived Original Series Onefinity controller, the CNC controller supports Modbus so you wire the VFD’s RS485 communication to it instead.
A water-cooled spindle needs a water coolant pump. VFDs have relay outputs for this purpose, with which the VFD switches spindle coolant pump on when the spindle runs and off after spindle is stopped. You may even program your VFD in a way to continue cooling of the spindle for a while after the spindle was stopped.
Similarly, if your VFD has enough control outputs, it can control an external relay which is connected to your dust collection system and can switch it on an off automatically.
Here you can see a circuit diagram which shows how the VFD can switch the dust collector on and off automatically:
It has an additional manual switch, so that you can still use the dust collector for other power tools at the same time, like a circular saw and others, while the VFD can switch it on and off automatically (by the CNC) at the same time.
There are however other ways to switch your dust collection on and off than a relay directly connected to the VFD control output. Big dust collection system manufacturers offer solutions where you simply put an inductive sensor contactlessly over the motor cable of a power tool and it senses if it’s on and turns dust collection on. One example is shown here: Felder automatic start of dust extraction system. Another is the iVAC Pro Switch. In those cases, you would put the inductive sensor over the spindle cable, which means the VFD output cable, not the VFD input cable.
Welcome to the forum!