Taz5 Z-axis binding (photo)

Taz5 here, workhorse machine. But has developed a Z-axis stuckage. You can see that it can complete many layers, but it will either get stuck on a layer or it will get stuck then continue and so on.

The Benchy in the back and isn’t bad for this printer, but on the box you can see that it got stuck on a layer and never went up. I have also observed it getting stuck at other heights and continuing.

I leveled the X axis to trying to get left and right Z correct. I watched these prints and didn’t hear or observe anything obviously wrong.

Most likely the gantry is not level. Check that:

  • Frame is square and screws are tight
  • Check gantry with a bubble/digital level, adjust by rotating one of the lead screws
  • Check that the bed is level.
  • Optional: use digital gauges to further check that the gantry is parallel to bed. I like a digital gauge positioned near the two corners of the bed. Check the front corners, then move the bed forward to check the back corners.

The process is a little backwards, but if your bed is really out of level then leveling the gantry to the bed will just cause it to be skewed… and thus bind.

Hope this helps, the next step would be to check the Z steps.

Thanks for the push in that direction, I’ll keep trying.

I noticed that all the bearings on this machine are really worn, can out of spec bearings on that z-axis allow it to shift and bind?

I experienced severe binding some time back. was severe enough to stall a z-stepper. I was sure I had a bad motor till I started poking around. Unfortunately the Z-axis has 2 stepper motors. When 1 of them binds, it’s not pretty. Causes:

  1. X-axis rails (steel bars) are steel but frame is aluminum. Different coefficients of thermal expansion. That combined with the lunar phase when assembled :wink: can cause binding.
  2. Lack of flexibility in the framing, no take-up. Item 1 is unavoidable to some degree. Some strain-relief should have been designed into the chassis.
    My fix:
    a. The 4 screws in flanged nut that runs vertically on Z-axis leadscrew, I loosened them on 1-side by removing and reinstalled with threadlocking compound (Loctite) to just lightly snug. This allows thing to slip in the horizontal direction. This relieves center-distance error between the LH and RH lead screws.
    b. The block that the above 4 screws thread into, it also has another set of 4 horizontal screws that support the X-axis gantry rails. I loosened 3 of them per the above Loctite method but kept 1 screw tight. This joint supports weight in shear so 1 screw should remain tight. This correction relieves any twist or angular misalignment.
    I wonder how many spare stepper motors Lulzbot has sold to fix this problem? Removal of parts to replace a perfectly good stepper motor can relieve strain and misalignment to the degree that the symptoms disappear without correction of the root problem.
    Hope this helps. Print on baby!
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Thanks, I played with the X-gantry height enough that it must be something else. I’ll play with things related to the framing and connections to the leadscrews.