Upograding an old Lcnc system.

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10 Apr 2024 14:55 #297933 by bevins
Hi guys, haven't been around in a while. Hope all is good with everyone.4

I have a customer that has an old system I did about 7 years ago and the machine has been moved. Getting a weird issue. With every turn of the ballscrew it jumps. With the halscope I can see the f-error and then it corrects itself and it jumps abpout 1/16 of an inch.

I am having a hard time trying to figure out what is causing this.IT is only doing it on the X and Y axis. The Z is perfectly fine.
If I disconnect the velocity command from the mesa 7i77 card and put a battery on the wires going to the drive it works smooth. This I am baffled with.

I would like to upgrade Lcnc to latest version that can update if required. IS the version 2.9 iso version the best way to go? Also the configs I dont really want to start over so how would I get the old config to work on 2.9 version. I think the old opne is 2.6 or 2.7.

Thanks for any ideas,

Bob

 
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10 Apr 2024 15:08 #297935 by PCW
Replied by PCW on topic Upograding an old Lcnc system.
Once per turn issues may be mechanical (loose coupling)
or encoder problems (dirt on the code wheel)

If you look at the plot, it appears that the feedback data (from the encoder)
just stops at some point.

Do the axis lose position? That is, can you jog back and forth through the 'thump"
and end up in the same mechanical position?

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10 Apr 2024 20:53 - 10 Apr 2024 20:54 #297961 by bevins
Doesnt really loose position. I dont know to what accuracy but If It doesnt seem to do it when I put a battery on the drive velocity input. IT works fine until I get f-error. I jacked up the ferror in the ini so I can see it move through the transition.
Last edit: 10 Apr 2024 20:54 by bevins.

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10 Apr 2024 21:01 - 10 Apr 2024 21:03 #297963 by bevins
Idont know if I mentioned the exact thing is happening on X andY but not Z and they have the same Servo's, encoders and drives. Plus the encoders are sealed in a casing inside the servo motor cap.
 
Last edit: 10 Apr 2024 21:03 by bevins.

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10 Apr 2024 22:51 - 10 Apr 2024 22:57 #297970 by PCW
Replied by PCW on topic Upograding an old Lcnc system.
You would not expect an error/thump running the motors open-loop
as the error seems to be encoder related (and the encoders are not
involved in open loop motion)

It might be wiring related ( intermittent open or short in the encoder
wiring that's ball screw position related

Are you sure you only get the error once per turn?

Another possible cause of the following error would be loss of the analog output
briefly but having this happen once per turn also suggests some kind of wiring
intermittent
Last edit: 10 Apr 2024 22:57 by PCW.

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11 Apr 2024 04:25 #297985 by rodw
Replied by rodw on topic Upograding an old Lcnc system.
Moving a machine really shakes them up. I would reseat every plugin terminal on the mesa boards and check each screw terminal for tightness before doing any additional troubleshooting. I moved a shop once about a mile and 4 out of 5 PC's failed to start until I did this.

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14 Apr 2024 19:55 #298253 by bevins
Well it was the encoders.

 
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14 Apr 2024 20:50 #298256 by rodw
Replied by rodw on topic Upograding an old Lcnc system.
Thats really shaken up!

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