Author Topic: Strange problem with Z-axis and spindle [SOLVED]  (Read 8919 times)

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Offline Moonclaw

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Strange problem with Z-axis and spindle [SOLVED]
« on: August 16, 2014, 01:29:36 PM »
Hi All

I'm trying to retrofit a Morbidelli Author 502 CNC with a dspMC/IP controller but have run into a strange problem. The XYZ axis are controlled by Vickers AZE-CC4Q analog servo drivers and the spindle by a Frenic 5000G9S, also in analog mode. I've got the axis calibrated and they all move smoothly and the spindle starts up and it's speed can be controlled from Mach3.

So far all good but when running G-code and you command a downwards move on the Z axis while the spindle is active (M3) it will cause the Z axis to go all the way down to the end stop. The speed of the movement seems fixed, i.e. not related to the commended feed speed and it doesn't matter if the G-code command is G0 or G1. Upwards movements are fine, also any movement with the spindle off is fine.

Anyone having any ideas about what is going on here? I'm completely stomped! I've checked all wires and there doesn't seem to be any shorts. There isn't any wires connecting the two servo drivers together other than the analog and digital signals that are hooked up to the dspMC breakout boards. The digital direction and activate signals all go through relays and aren't connected directly the drives anyway.

Any help at this point would be appreciated!

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« Last Edit: August 27, 2014, 07:01:47 PM by Vital System Support »

Offline Vital System Support

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Re: Strange problem with Z-axis and spindle [SOLVED]
« Reply #1 on: August 18, 2014, 04:42:38 PM »
Hello,

I just downloaded your XML profile and tested with G0 and G1 commands on the Z axis (up and down) and it works fine with or without the spindle off. Is there something specific that needs to be done to trigger the error?

Is there any more info that you have on the problem? Do you have the latest firrmware and plugin updates available from our website?


-Marc Lim
Vital System Inc.
« Last Edit: August 27, 2014, 07:01:18 PM by Vital System Support »

Offline Moonclaw

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Re: Strange problem with Z-axis and spindle
« Reply #2 on: August 18, 2014, 07:05:31 PM »
No, I played around with it a bit more today, turns out that I can trigger it by manually activate the output for the spindle and it z would start to move. The movement stops if the output deactivates so when running G-code I can just stop the programme and prevent it from hitting the limit switch. If I do that then occasionally the phenomenon goes away,  I. E.  I can start the spindle and move both up and down. A restart of mach3 or activating the estop brings it back though.

The dspMC is fairly new so I haven't thought about upgrading it but I'll try that tomorrow.

Offline Moonclaw

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Re: Strange problem with Z-axis and spindle
« Reply #3 on: August 18, 2014, 07:34:12 PM »
Is there any way to view the voltage on the analogue outputs on the dspMC?

Offline Vital System Support

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Re: Strange problem with Z-axis and spindle
« Reply #4 on: August 19, 2014, 07:02:32 PM »
Hello,

You can check the analog output data with a multimeter. It should be between +/-10V. When the DSPMC is not outputting any thing, you could get values in millivolts which is fine.

By the way, when you move the Z axis, are you doing any kind of move aside from G00 or G01?


-Marc Lim
Vital System Inc.

Offline Moonclaw

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Re: Strange problem with Z-axis and spindle
« Reply #5 on: August 19, 2014, 07:30:11 PM »
Hi,

No, I'm just moving the z.

Well I've been checking the voltage with a multimeter but I was wondering if it was "ordered" from within the dspMC or originating from somewhere else (by a short or something).

It did occur to me earlier tonight that it might actually be an issue with the pulse feedback. If the spindle somehow introduces pulses in the z feedback the PID would think the z was moving and would try to correct that by applying a corresponding voltage. if the z wasn't moving this would cause it to move, right?

Thanks for your help!

Offline Vital System Support

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Re: Strange problem with Z-axis and spindle
« Reply #6 on: August 19, 2014, 07:53:38 PM »
Hello,

You can try a quick test. Disable the z axis by setting the control output source of the Z axis to undefined in the plugin config. Open the DSPMC Status window which can be accessed from the top menu of the Mach3 main window ("Plugin Control" -> "DSPMC Status"). Then do the motion process that seems to be causing the error and see if the encoder channel for Z moves at all. This should be able to tell us if there is a problem with the encoder wiring (e.g catching noise form the spindle).

-Marc Lim
Vital System Inc.

Offline Moonclaw

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Re: Strange problem with Z-axis and spindle
« Reply #7 on: August 27, 2014, 06:46:18 PM »
Hi Marc

Just wanted to update you on my project. It did turn out to be an disturbance introduced from the spindle generating extra pulses.

Well, that got me to take another look at the whole encoder setup and I ended up in another set of mysterious phenomenons. To make a long frustrating story short, I've got new TTL encoders in the mail 8)

Many thanks for the help!