Chasing an Axis Differential Error (CNCSNW?)

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martyscncgarage
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Chasing an Axis Differential Error (CNCSNW?)

Post by martyscncgarage »

For the benefit of everyone, hoping Marc Leonard with CNCSNW will chime in and describe how he would chase down a "412 Z axis(3) encoder differential error" on an axis.

An old client of mine has a large router (48"x48" which is used to cut ICE Sculptures. I upgraded the control to an All in One DC a little over two years ago.
Pictures of the machine can be seen here: https://photos.app.goo.gl/TvGPjTTTQT8ezUag9

Recently, he started getting a "412 Z axis(3) encoder differential error" intermittently. He would reset the control and continue on with the job. Starting to get a bit more frequent. He reached out to Centroid and they sold him a new replacement NEMA 34 DC Brush Servo. (Centroid/Glentek) to replace the old NEMA 34 DC Brush Servo (I believe it is a Redcom) So we are starting with replacing it today.
(Pictures and report attached)

The machine is obviously in a Freezer (no fun to work on) and the control is outside the freezer. So the cables from the machine to the control are fairly long.

I'd like to know (as do we all) the logical approach to chasing down the 412 Axis encoder differential error"
I was thinking its the encoder on the motor, but it could possibly be the cable, so I am taking one to swap in temporarily if needed.

Thanks in advance
Marty
Attachments
Old Centroid Motor.jpg
Armitage Ice report_0626192246_2021-10-27_19-29-45.zip
(252.42 KiB) Downloaded 5 times
Centroid-Glentek Servo.jpg
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cncsnw
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Re: Chasing an Axis Differential Error (CNCSNW?)

Post by cncsnw »

If the issue is not the motor (or rather, the encoder in the motor) then it is almost certainly the cable. Swapping out the cable is going to be the simplest test.

If you ultimately find there are cracks in the encoder cable, it would be worth researching some alternatives. Compare the temperature range and continuous-flex ratings for Belden, Helukabel, and any other higher-quality shielded twisted-pair cables you can find.

What is the temperature in the freezer?
martyscncgarage
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Re: Chasing an Axis Differential Error (CNCSNW?)

Post by martyscncgarage »

cncsnw wrote: Tue Nov 09, 2021 12:12 pm If the issue is not the motor (or rather, the encoder in the motor) then it is almost certainly the cable. Swapping out the cable is going to be the simplest test.

If you ultimately find there are cracks in the encoder cable, it would be worth researching some alternatives. Compare the temperature range and continuous-flex ratings for Belden, Helukabel, and any other higher-quality shielded twisted-pair cables you can find.

What is the temperature in the freezer?
Marc, I asked the client to inspect the cable. I will have several encoder extension cables removed from my Atrump, that I can connect together and test if it is not the encoder. Good point on the insulation temperature rating of the cable. I don't remember exactly what the temperature is. Some how I want to say its about 10 degrees. But will know soon!
Marty
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eng199
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Re: Chasing an Axis Differential Error (CNCSNW?)

Post by eng199 »

Marty,
Another encoder cable option is Alpha 86604CY. Its temperature rating is: -10 to 105°C(static), +5 to 105°C (dynamic) . Centroid could sell you some (PN 8723) if you can't find a reasonable length available online.
martyscncgarage
Posts: 9116
Joined: Tue Mar 28, 2017 12:01 pm
Acorn CNC Controller: Yes
Allin1DC CNC Controller: Yes
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MPU11 & GPIO4D -w/ 3rd Party Drives: No
DC3IOB: No
CNC12: Yes
CNC11: Yes
CPU10 or CPU7: Yes
CNC Control System Serial Number: none
Location: Mesa, AZ

Re: Chasing an Axis Differential Error (CNCSNW?)

Post by martyscncgarage »

Thanks Marc and Matt,
Turns out it seems the encoder was going bad in the old motor. New motor/encoder seems to be working.

Thanks for the PN on that cable Matt!
Marty
Reminder, for support please follow this post: viewtopic.php?f=20&t=383
We can't "SEE" what you see...
Mesa, AZ
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