z axis not working well

Troubleshoot issues with the Little Monster
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sandrine.bon
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z axis not working well

Post by sandrine.bon » Mon Oct 02, 2017 1:34 pm

Hello

I can't make my tevo LM work properly. I've correctly built it but when I manually move the arms, the z axis does not respond every time. I switched the stepper motor with another one but the problem remains the same.
I've tightened the belt and sliders as much as with the other axis so is it a problem from the motherboard ?

Thank you for your advices.

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Charles
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Re: z axis not working well

Post by Charles » Tue Oct 03, 2017 9:21 am

Possably a cable problem. Is it possable to swap the cable from the motor to MB with one of the other Axis to rule out a cable fault ?


Charles

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MikeKölbl
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Re: z axis not working well

Post by MikeKölbl » Sat Nov 04, 2017 2:24 pm

Hi,

I have the same problem with the Z axis working some time, some time not.
Built the printer yesterday, calibrated it - all according to the manual.
Yesterday and today I did some test prints. There was a pause of about two hours - during this time the printer motors were homed and holding the head, nozzle was at 210 degrees and heatbed was off. After the pause I inserted the SD card and tried to print a STL file.

Printer was heating the bed up to 80 degress and hotend stopped 1 degree before the should value of 210.
Board then crashed and rebooted. Since then, Z stepper is not running when pressing "Home" and since 10 minutes the printer is ignoring all commands. Even a hard reboot by disconnecting power, waiting 10 seconds and reconnecting power did not solve the problem.

Did anyone have had the some or a similar issue yet?
Going to let the printer cool down for a few hours now and will retry. If it does not work will try to replace the files on the SD card (Flash) with the backup I made of the card before turning on the printer for the first time. Maybe this helps.

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MikeKölbl
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Re: z axis not working well

Post by MikeKölbl » Sat Nov 04, 2017 4:42 pm

After waiting a few hours I turned the LM back on.
It is working again, heating and printing. So it seems to me there is either an overheating problem with the MKS, cold solderings on the board (hard to see cause the PCB is painted) or a firmware/configuration issue. I will check the current config against the initial one to see if there has something changed.

The Z axis problem is still existent. Powering on -> Home will move X, Y but Z stands still.
You have to move it up by hand. After moving it half the way up, the stepper begins to run.
Tested with printer off and printer on + motors off: Z can move freely, belt not too tight.

I expect it not to be an overheating issue because it happens only after turning on the printer and first time Homing (after powering on). Z stepper is working fine during print and is homing without issue after print. Seems to be firmware or configuration issue to me.

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royg
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Re: z axis not working well

Post by royg » Sun Nov 05, 2017 2:42 am

Can any LIttle Monster owner help with this one ?

RoyG
Tevo Tarantula - Large Bed - E3dV6 - BLTouch
OctoPi (on a Raspberry Pi 3B)
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MikeKölbl
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Re: z axis not working well

Post by MikeKölbl » Sun Nov 05, 2017 3:03 pm

Hi everyone,

answering my own question...
I have just switched the Z and X servos and sensors and then all servos worked again.
I did a new calibration and printed a test file without any problems.

Now my servos are:
X
Z Y
[Front]


This leads me to the following result:
In my case it would be malfunctioning servo cables.
Hope this helps any other Little Monster owner with same or similar problems.


Cheers,
Mike

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