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Cincinatt Arrow 750 - potential spindle drive death

Burf86

Plastic
Joined
May 10, 2021
Hey guys, recently acquired an Arrow 750 and thanks to the grand help from folk on this forum I managed to get it up and running and made few bits with her, but I've now run into spindle problems, it intermittently won't run.
The problem just came out of nowhere, or it might be attributed to a crash... So I did have a crash, nothing too heavy I don't think. The Z was rapid down and the tool length was incorrect, so the tool holder hit the piece in the vice. The spindle wasn't turning for this one. Everything seemed to be ok and I carried on. Had a second semi-crash where the tool wasn't long enough for the pocket it was helixing into, and again the tool holder hit the piece in the vice. The spindle was on for this one but I managed to hit the emergency stop before things got too wild, surely no more load than a heavy cut?

Then one day I switched her on and during alignment, the spindle turned a small amount and then nothing else. Turned off and on again but no luck. The next day she fired up just fine but wouldn't give the spindle high RPM's. The next day she worked fine and I made a few bits and she died mid-program. The next day wouldn't even move the spindle for alignment. The next day worked all good all day. The next day she moved a small amount during alignment and now here I am...

The warning that comes up is;

Alarm 39-97
Spindle drive not ready
Cause 1: The spindle enable signal is not on, but the spindle drive ready signal is on. It should not be on at this time
Cause2: The spindle enable signal has been set on, but the spindle drive ready signal has not been received.

I have spoken to my machine engineers and they have said I can take the spindle drive out and send it up to them for testing to see if it's actually the spindle drive causing the fault, but figured I put some feelers out here as well. The fact it has been intermittent has me questioning whether it's a drive fault, or a loose connection caused by the crash, or some dirt has been shaken loose by the vibrations?
 
I know nothing about your machine, but if the drive relies on a speed sensor signal from the motor there's a good chance it's not starting because it doesn't see the signal.

If it starts to spin, but then stops with an alarm this is a possibility. If it doesn't start at all with an overload alarm that would be more indicative of failed IGBT's, bad motor or bad cabling.
 
Following Garwood comments: when it doesn't start, have you tried powering it off, rotate the spindle and try again? My thought is that, if there is an encoder disk to sense the angular position and speed of the spindle, there might be a "bad spot".

Paolo
 
I think you guys are onto something.
There are three sensors on the spindle, two have red lights and the third does not light up...
 
Following Garwood comments: when it doesn't start, have you tried powering it off, rotate the spindle and try again? My thought is that, if there is an encoder disk to sense the angular position and speed of the spindle, there might be a "bad spot".

Paolo

The ones I have experience with use a metallic trigger wheel with teeth and magnetic sensor to generate a sinusoidal waveform signal. Usually two overlapping waveforms 90 degrees apart. 90, not 180 degrees so the motor direction can be determined by the signal.

The drive amplifies these analog signals and converts them to a square waveform used by the drive electronics to determine motion, speed and direction of rotation.

Typically the drive manufacturer will have a procedure to troubleshoot this signal with an o-scope.
 
Hey everyone, thanks for the input so far. Much appreciated.
Things move at a glacial pace around here, so sorry for the extended radio silence in this thread.

I am still having trouble with the machine, after much poking and prodding I sent the spindle drive and power supply away to be repaired. Apparently, both had gone down. Luckily the power supply was repaired under warranty, but the spindle drive was mega spendy. I've placed them back in the machine today and, unfortunately, I am still getting the same problem. Alarm 39-6 Axis drives not enabled.

It was mentioned that the door switch could be causing the trouble. I tested with a new switch and there was no change so I returned it. I then purchased a new cable and replaced that, wired up with the original switch, no change.

When I make the second press of the green button to "give the machine power" and run around the back to have a look. The contactor has closed but the power supply does not come on. No lights are on before or during the second press. The spindle drive and axis drives all have the lights on before and during the second press. I'm assuming the power supply isn't at fault because it's just back from repair (emphasis on assuming), so what is the machine checking for before it turns on the power supply?

I have spoken to the firm who repaired the parts and they have said I need an engineer to come visit, I just cannot afford to be paying £50 an hour for them to drive here.
 
The PSR is getting voltage when the contactor makes a connection after pressing the green button for the second time, about 135V across the three input connectors at the bottom of the device. There is also voltage in the cables that connect the PSR to each axis drive.

Surely this would mean the problem is within the PSR?

The error code is saying that the axis drive ready signal, or the servo ready signal is not being received.

Edit: Measuring phase to phase I get 230V, measuring phase to ground I get 130V
 
I found this article
Common CNC Machine Failures and Troubleshooting Tips
read the "How Do I Fix a Problem with the Power Supply?" section and took the DC wires from the PSR to find it was actually producing a voltage.

Turns out I'd crossed the DC cables between the Z and Y-axis.
Feel a complete fool, but so happy to have found the problem.
 








 
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