Z axis misalignment after a time

My Z axis pretty much always misaligns about 30-45 minutes into a print. Hard to say for certain if it is just time based, but I can print a thin 40 mm tall rod in ~15 minutes usually with no problem, but a larger object only 20-30 mm tall might start misaligning partway through.

In Cura, I can raise the Z axis via the control panel all the way to the top and back down over and over with no problem. This only happens when it is actually printing something.

What printer are you using here? This sounds like it could be an issue caused by either over-tight screws on your your z-axis lead screws, or by an overheating issue on the z-stepper driver.

Taz 6. I would assume over-tight screws would be noticeable during non-printing raising and lowering of the z-axis, though.

In that case, it sounds like your z-stepper driver on your Rambo may be overheating. Does the case fan come on during your prints? The z-stepper driver is the only driver that needs to move two motors on the printer, so it does need adequate cooling. Another possibility is that there is not enough power getting to your printer, causing the issue to only show up in prints, when there are multiple motors moving and the heaters are going. If that is the case, then you may want to try making sure that your printer is plugged directly into a wall, without using any surge protectors or power strips.

Alright, I think it’s a cooling issue, for anyone who happens by here looking for solutions to the same problem.

Haven’t been printing any large pieces lately, so haven’t been able to test it too much until the past few days. Tried plugging it in to different outlets (have experienced problems on other printers where it would just stop printing if I turned on my microwave, so who knows), seemed to have no effect. Took off the side panel and have a large-ish 12v computer fan pointed directly at the circuitry. Definitely seems to help, still not 100%. The fan itself is not super powerful, Z axis still misaligned toward the end of a 2 hour print. Turned up the juice to the fan (separate power supply, not connected to printer) and I was able to get past that piece without issue. All the regular fans appear to be working, though. Not sure why the regular fans are no longer sufficient.