CTC DIY Printer Z-axis wobble repairs

First, an example of the wobble: https://drive.google.com/open?id=1sz34dHOgt0r1nmJpUiQsRUgLw2h_Svmb

Now a solution suggested on Thingiverse, found from a youtube video:
https://www.thingiverse.com/thing:2135784   I printed this, and it was necessary to file out the groove on it due to the effect of the Z-axis wobble. The side of the piece shows the effect of the wobble ( see picture)

This is the mechanism that has to be modified: [Picture 2]

and this shows where the piece fits, [picture 3]

with the metal piece screwed into the white piece and the rest of the mechanism resting on it.

How to do it.
1.  Undo threaded bar from coupling and remove it.
2.  Remove slider rod.
3.  Undo metal threaded part.
4.  find appropriate screws and mount  this threaded part on to white piece.
5.  Replace slider rod, and clip white piece in to it.
6  Replace threaded rod, through mechanism and through added piece.
7.  Align x-axis mechanism  for correct vertical positioning.
8  Test
9.  If successful, repeat  1-8 on other side.

This works, much less wobble. Here is the final picture. As the rod wobbles so does the white piece, but the frame doesn't. I had to do both sides. One of the main difficulties was finding small screws that would go through the metal, screw into the plastic, but not protrudre into the dome of the white plastic where it would affect the sliding motion.  It was necessary to reset the nozzle height afterwards.

All of this thanks to jpnurro the designer who put it on thingiverse.


I am quite pleased with the results, but will still work on how I can stop the threaded rod from wobbling, which is the cause of the problem.

11 May 2020
The problem seems to have got worse again, I don't know why, except that the Z-axis spindle does seem to wobble around a lot.  I have tried putting shims into the coupler where I think I can centre the spindle, but that doesn't seem to help.

This morning I put the X-axis machinery up on trestles and have removed the Zaxis threaded spindle.  The Coupler wobbles. THIS IS BAD NEWS.

In effect, back to square one. Does this mean that the axle of the stepper is bent? I have  seen that mentioned in a YouTube video.  Or is it that the stepper motor is mis-aligned? One of the screws bolting it on to the frame was looser than the others.  No. The way that the axle turns indicates that this last is not the problem.

12 May 20202 Have replaced coupler with plastic tubing and wobble is so much reduced. No signs of wobble in the stepper motor  axle.