Z-Axis motor skipping

K8200 3D Printer K8200 - Assembly and user manual
1

Hi,

I just finished my build, (nice build btw, I really enjoyed doing it)
and now I am testing with the manual control. I am having issues on all 4 motors.

I focus on the Z-Axis in this post.

My Z-Motor axis is skipping. I can see it goes up and down, as I want. But it makes alot of “skipping noises” which are pretty.

[color=#0000FF][update][/color] this morning the motor does not spin as it did yesterday, it just spins a bit and back, again and again,

The things I tried were:

-Check if the motor moves itself. I saw some movies on the internet, where the motor bracket kept flexing when the Z-cariage was being moved. I don’t seem to have that problem.
[color=#0000FF][update][/color] - I see it flexes about 1-2 mm.

  • Check threaded rod top end on the z-motor, and see if unsupported it moves around alot. This seems ok, but since the Z cariage is still supporting it, I did not manage to see it completely unsupported.
    [color=#0000FF][update][/color] - I disconnected all, except the axis from the motor, and see now that the deviation from the center of the axis on the top of the construction is about 0.5 cm. I heard people talk about 2 cm, so I assume, I am prettty ok there.

-Loosen the bolts on top, just to make sure they were not too tight. This seemed to have no effect.

-Loosen the hex bolts that hold the cariage, so there is room for movement. This seemed to have no effect.

-Lubricate the rods (the threaded, and the smooth one as well). There might be a tiny difference, but I’m unsure it made any real difference.

-Increase Z-motor voltage up to 0.54 v. There might be a tiny difference, but I’m unsure it made any real difference.

So, at the end the problem is still there. The carriage seems to move pretty smoothly, as if not for the loud ticks that sound like skipping.
[color=#0000FF][update][/color] Hmmmmmm, now completely unsupported, the motor does not rotate anymore, is it possible I blew the motor with too many tries? How can I know if it’s the motor or the controller, that is problematic?

  • Does anyone had the same issue?, and what more can be done to analyse this?
  • Which lubricants are ok to use on the rods, and which should at all cost be avoided. (I think I might have been a bit hasty and went for “any” lubricant, and am wondering, if I should consider another lubricant)

Thanks
C51

2

Hi chaos51,

it seems like you pretty much covered all the basics already. Apart from the ticking noise, you can directly ckech whether steps have been lost. When moving the axis 10 mm up or down, the rod should do exactly eight full turns. You can also enter a G1 command in the manual control tab to move the axis by 1.25 mm, corresponding to 360° rotation of the rod.

When the motor does not turn at all, unplug its connector from the controller board and measure the resistances between all the pins. Pins 1&2 and 3&4 should have a similar resistance in the range of 1-3 Ω, all other pin combinations should measure as open connections.

You can also switch two of the motor connectors to check whether it works on a different output of the controller board. Keep in mind that the X and Y axes use higher rpm then Z and E axes, i.e. adjust the speed accordingly when performing such a test.

As for the lubricant: the rod is probably fine with any standard oil. In case you also want to use it on the bearings, make sure that it’s a non-resinous oil or grease.

Cheers,
kuraasu