I've noticed a decline in the print quality of my Ord Hadron, and I can't pin down the cause. Flat walls used to be perfectly smooth, but now I'm getting ridges. Not very pronounced, the light needs to hit just right but often it's pretty obvious-
The temp graph is completely flat, and I've tried a few different filaments from different suppliers. I've also tried both Bowden and direct setups with Bulldogs and E3D, and used Slic3r and S3D for slicing test cubes.
Z movement is not consistent. It ranges over about .03-.04mm, and can be over or below the commanded distance. I replaced my helical couplers with solid printed couplers with several set screws so I can tweak the angle of the threaded rod (2mm pitch trapezoidal). The rods are unconstrained at the top and have only slight wobble. I am using isolators at the gantry -
Ord Anti-Wobble but don't get better results than having the lead screw nut attached directly to the gantry. The upright extrusions move forward and back about .02mm, but it isn't enough to change the nozzle height (I have two dial indicators for checking that). There is no detectable sideways movement of the gantry.
I'm confident in ruling out wobble as a cause of inconsistent Z movement. I don't think it is a driver or vref issue because sometimes the movement overshoots the target distance rather than just missing steps all the time. I've checked it with both digital and analog dial gauges,so it isn't just variations within the digital gauge's range of accuracy. The lines could be caused by inconsistency in X or Y movement, but in that case I would expect X faces to look different from Y faces. Is it normal or accepted to have Z moves vary by up to .02mm above or .02mm below the target distance? Steps/mm are correct, the coupler spins exactly the correct amount every time. Is there something about the lead screw nut that could be causing this variation? There is about .05mm of backlash, but the gantry only moves up during a print.