Is it possible? (G540 spindle control)

[fretsman]

I'd like to inquire about a possible speed controller for my Taig Lathe CNC I've built. I have no speed control through Mach 3 but would like to if possible. I'm using the MC 60 Treadmill controller with the Bosch Treadmill motor and I'm including the wiring diagram that was furbished with the controller. The only problem I'm seeing trying to set this up is the fact that the MC60 controller has to start at 0 rpms and then be turned up to the desried speed, it can not start up at any desired speed that I would like it to.

Is there a way that I can connect to Mach 3 to control something like this or should I be looking for a completely different motor/controller setup? If I am able, can someone help with the wiring from the controller to the 540?

I'm including a couple of pics of the lathe itself.

Thanks for your time.
Dave

[phomann]

Hi Dave,

Ok, measure the voltage across the red and the black wire of the manual speed potentiometer on the motor controller.

Be careful not to touch any of the wires to the potentiometer as they are likely to be at or near mains potential (110V). If the voltage between the read and black is not greater than 12V, then you should be able to connect the G540 analog outputs in place of the potentiometer.

Please take note. There is likely to be mains potential voltage on these potentiometer wires. If you do not understand or are not confident in doing this yourself. Find a qualified electrician and get them to do it for you.


The motor controller has a safety feature so that it won't turn on unless the speed pot is turned down to zero. This shouldn't be an issue as the G540 will be putting out 0V initially, until a speed is commanded by Mach3.

Also, what you could do is leave the potentiometer in place, but also connect the red and black wire to the G540. Then use a SPDT throw switch that connects the white wire to either the potentiometer wiper OR the G540 VFD control voltage output. That way you will have auto/manual control, just by flicking the switch.

Cheers,

Peter.

[fretsman]

Hi Peter,

Thanks for the reply, and yes, I will pry her open and have a test at the voltage off the black and red wires for the pot. If it is indeed 12V or under, which wires will be going to posts 7, 8, and 9 on the 540?

http://www.geckodrive.com/upload/G54...3%20MANUAL.pdf

Thank you Peter, it's very admirable that you (Homan Designs) are helping me with a Gecko product

Cheers right back atcha-
Dave

[phomann]

Hi Dave,

When you measure the voltage between the red and black wire, whichever is positive with respect to the other (I'm assuming it will be the read, but you need to measure it to be sure) needs to be connected to the G540 POS 9 VFD +10V. The other is connected to the G540 POS 7 VFD GROUND. The white wire (Pot wiper) is connected to the G540 POS 8 VFD OUTPUT.

As to the Gecko drives, they are excellent units, Mariss is very busy, so I don't mind helping.

Cheers,

Peter

[fretsman]

Thanks again, Peter, this is fantastic and is much appreciated. I love the idea of the switch for manual speed overide as well.

Now I'll just need to wire up my optical switch and add the slotted disk to the pulley and I'll be good to go!

I'll let you know how it goes -

Dave

[fretsman]

Looks like I'm luck this time around as it measures 11.98v and yes, the red is indeed the positive.

Thanks again, Peter-
Dave

[phomann]

Originally Posted by fretsman Thanks again, Peter, this is fantastic and is much appreciated. I love the idea of the switch for manual speed overide as well. Now I'll just need to wire up my optical switch and add the slotted disk to the pulley and I'll be good to go! I'll let you know how it goes - Dave

Dave,

The opto inputs on the G540 are pulled up to 12V via a 2K2 resistor and the opto emitter diode.

When you get your opto switch, make sure that is is an open collector one (Most basic ones are) and not a logic drive one.

Have a look at my engineering note EN002. It shows a QRB1134 sensor, but the picture shows the sensors connections.
http://homanndesigns.com/store/index...id=3&chapter=0

Using the sensor diagram as an example, Connect
'E' to Pin 12 (GND)
'C' to Pin 1 (INPUT1) or other input.
'K' to Pin 12 (GND)
'A' to current limiting resistor that is connected to DC power supply**

** if you have a setup like the schematic in the G540 manual then yo would use the relay power supply. If this supply is 12V then use a 1K resistor.

Cheers,

Peter.