[Closed] Z-axis failure
Have to get advice on a failed print. It appears that the z-axis motors just stopped moving during the print. Before cancelling the print, I observed the z-axis motors slipping with no movement on the axis. This is the third print on this printer, but the first time this has occurred. After stopping the print the z-axis seemed to move smoothly up and down using the controls. I then lowered the z-axis to the build plate and the controller reported z-axis at +3.8, this seem consistent with z-axis slip
Maybe related, during x/y/z calibration the machine will not do the upward Z move on 4 out of 5 attempts. It does seem to work if I move the Z-axis near the top before starting the calibration. The z-motor threaded shafts seem to move freely by hand when deenergized.
If you XYZ calibration fails I would start there by disassembly and retracing those steps. It worked for me.
I am currently on a quest to locate the gremlin. I tried printing, re-slicing and printing the same piece and it failed at exactly the same Z-height. I then made a test tower which did not jam up, but did print a very wide layer at the same Z position. I checked the gcode at those heights and it seems to be fine, but there is a ~1 mil high, very wide layer at the same z-height the previous two prints failed, but the printer got past it. It looks like it had a problem getting past that position and printed a few layers worth of filament without advancing along the z-axis, but it would have to have done that over multiple z-height increments to get the effect. Unfortunately I stopped the print early, or else I could have verified the theory by comparing the printed height with the designed height.
You can see in the image, the wide band on the tower at exact same height. I inspected the lead screws for damage and didn't find any. I put pieces of tape on the dust caps, which are currently about 5 mls above their respective motors. The dust caps loose synchronization concurrently with the fail. I have not been able to see it happen yet, so I can't yet say which shaft is hanging up, but that is where I am looking.
The lead screw dust cover nuts (aka jam nuts) can wedge and jam the motors. The T-nuts can also jam, but less likely.
The most common problem is something is snagging a wire or interfering with the X-carriage as it raises up. A wire tie hitting the power supply or Einsy case, a spool holder that is installed wrong, or even a screw tip that goes through the vertical frame to hold an accessory.
'aka' jam nuts, got that straight.
All your points of contact are definitely a possibility, but I been over every possible point of contact many times now (2 days worth of effort), so I'm sure it's not a point of contact other than maybe the duct covers. Once the JAM NUTS were moved up, I loosened the z-axis tops and cycled the z-axis at least a dozen times and tightened up the top caps. So for it seems to be printing and calibrating correctly. 3 tall prints accomplished so far with no errors.
Good luck to me.
Thanks for your inputs
If the issue continues, post up photos of the frame, rear of the extruder, the cable tail, and spool holder you're using. All angles. Whatever it is/was is mechanical; maybe not obvious to you, maybe obvious to others.
Will do... Thanks