Centroid Community CNC Support Forum

I wonder if I have the incorrect specs on my PRS rack. I've been operating under the assumtion that my 1/2" width rack is a 14.5* PA.

I might reach out to SB to see if they have that info on the SP2 (2007-2008ish era) PRS. If I'm after a 20* PA pinion gear that so seemingly might be a lot easier to find.

No PRS model used other than 20* PA rack

Well that's the best news I could hear. Thank you Gary. That makes findings gears a whole lot easier.

Hey All - I'm still pecking away at my wiring layout.

If I choose to run an EMI/RF filter inline to my VFD, does the filter belong before the contactor, after, or does it not matter?

My Yaskawa VFD manual also calls for RC suppressors (snubbers) if the unit is being used with a contactor, so I will be running those in parallel across the contactor for the single phase power.

Last, I'm fairly oblivious to what kind of cooling fans I should be running in my enclosure. I've seen everything from 240v AC to 24vdc for primary cooling. What's the communities advice here?

So I found the answer to my question the Yaskawa V74X manual (surprise surprise). So I'll be mounting the EMI/RF filter downstream of the contactor.



In doing so however I came across this warning regarding the use of a contactor for starting and stopping the drive or motor.



Understandably, cutting power in an emergency situation through the contactor by use of an e-stop is acceptable given the right scenario.

Further into the manual it states the following however:



In my wiring, Acorn would be waiting for a Spindle OK state from the VFD before ever sending analog signal to start spindle RPM. Alternatively, it would suggest that Yaskawa's instruction is to leave the VFD powered at all times... which seems less than ideal.

For my understanding, is it OK to use the contactor to power on the VFD drive via Acorn's control so long as the motor is not immediately being jolted into movement?

I guess further to the point, it seems my wiring selection and choice to control VFD power via contactor is one that is used fairly regularly, but am I shortening my equipment life by doing so?

Normal CNC and industrial control design is to maintain power to the VFD at all times, or at all times when not in a Fault or E-Stop condition.

During normal operation, you start and stop the motor with the "run" or "run forward" logical sequence input, without interrupting power to the VFD.

I have a contactor controlling power to my Yaskawa VFD (original to SB) that turns it off and on when I turn main control box power on and the Acorn powers up, and it's been fine. I believe that's how SB had it wired as well. If I had a commercial shop I might leave it powered on, but not in my garage when I finish for the night.

cncsnw wrote: ↑Sat Oct 31, 2020 9:10 pm Normal CNC and industrial control design is to maintain power to the VFD at all times, or at all times when not in a Fault or E-Stop condition.

During normal operation, you start and stop the motor with the "run" or "run forward" logical sequence input, without interrupting power to the VFD.

That's quite helpful for me. Not having gone through my bench test or fooled with the CNC12 software yet, is the output 'NoFaultOut' enabled basically instantaniously upon Acorn boot up so long as there are no faults detected?

Or does it only enable as soon as a program or macro is run?

I.e. If I controlled my contactor (powering the VFD) with the normally-open 'NoFaultOut' from Acorn that closes upon detecting no fault, it would in theory keep the VFD powered the entire duration that my machine was on, with the exception of hitting a fault or an e-stop trigger, right?

tkbot47 wrote: ↑Sat Oct 31, 2020 11:52 pm I have a contactor controlling power to my Yaskawa VFD (original to SB) that turns it off and on when I turn main control box power on and the Acorn powers up, and it's been fine. I believe that's how SB had it wired as well. If I had a commercial shop I might leave it powered on, but not in my garage when I finish for the night.

Tom, so you have a 24v DC PSU circuit that closes the VFD contactor upon power-up, that is also tied into your e-stop circuit in the event that you need to stop in an emergency situation? If your machine hits a fault, it then just drops the SpinFWD output to stop your spindle? Allowing the VFD to manage bringing the spindle to a stop on its own, rather can cutting power to it?

Yes, you should use the NoFaultOut output, either directly or indirectly, to control your VFD power contactor.

NoFaultOut will not turn on until the Acorn has booted up; the CNC12 software has started; and the PLC program has been downloaded or verified. Current PLC logic may also have it come up in a "Reset" condition, so that NoFaultOut will not turn on until you press/click the Reset button on the VCP.

PaulWall, you really should get your software upgraded to 4.50