Variable Speed Spindle
eMail if you are interested!
We have now finalised a source of a 1/2HP 3 phase motor and digital inverter for use as an alternative to the fixed speed motor currently being supplied. This will be configured with an interface so that speed can be controlled via the Mach3 spindle control, but is currently being tested using it's local control panel. One of the reasons this particular unit was selected.
There is now a program for the mill to modify the existing mounting plate for the motor and this will be extended to provide plates from blank material as well. The problem of mounting the 1/2" shaft Taig pully onto a standard 11mm motor shaft is proving a little more interesting, but I have initially gone with a spacer for use with a second spindle pulley since this is already bored out to take a larger shaft, leaving better wall thickness when machining the inner to 11mm.
As the inverter provides both direction, speed control and an on/off function, there is no need for an additional spindle control relay, although it is proposed that power to the controller will be managed by a secondary contactor that will only be powered while a system is in RUN mode. The ACS150 was chosen after checking through several options, but the main reason for going with it was the ease of providing a ready assembled cable harness which only connects to one end of the unit. Most others had supply at the top end.
Current tests show that 180RPM is probably the best we can do at the low end, below that there is little torque left, and at the top end the motor is running quite nicely at 6600RPM. This is in either direction. The control cable to Mach3 needs to provide an analogue 0 to 10V, an active high RUN and a direction signal, but in addition, there is an eStop control which will be linked to the error buss and a fault relay which will be sed in conjunction with the RUN state to indicate that a motor fault has been detected. The is left deactivated when there is no power, which is the case when systems are switched to SET mode, so we need to ignore error messages from the spindle hardware while it is disabled.
The current price is £250 + £20 shipping for the 1/2HP manually controlled version. Easily connectible to CNC breakout board.