Z banding but only at consistent intervals  

Z banding but only at consistent intervals

By chance if you turn your z-axis rod by hand does it have spots where it will fall back down a bit after raising it a quarter turn or so? If you are consistently having bad layer lines at specific heights the following might help

My prints had this symptom for ages and following steps fixed it:

Take the z-axis rod all the way out and roll it on a flat surface to see if it is bent. If so I guess its time to get a new one

Clean out the upper z-axis support threads. If you've had binding you may have some metal flakes in there

Loosen the two screws next to the z-axis support a quarter to half turn. Start screwing the rod in from the top half an inch or so then let go and see if gravity will continue screwing it the rest of the way down. If it doesn't fall naturally then your gantry may not be level, rod may be bent, or your threads still have crap in them.

This is where my issue was: Once its fallen/screwed down to where it is touching the motor see if it naturally tends to fall right into the coupler. If it doesn't then slightly loosen the two frame screws on top of the z-axis motor and with the newly found wiggle room your z-axis rod should fall right into the hole. Nudge the motor until the rod finds itself falling right into the coupler. Now you can tighten the motor mount screws and the coupler set screw and see if screwing the z-axis rod by hand feels smoother and stays after you let go. If so then its off to a test print

Hopefully this helps. I dealt with 9 months of layer lines telling myself "well this isn't a Prusa so it can't be perfect" before I found this fix.

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