z-axis drifting

While printing a large filament spool, I noticed that the z-axis seems to be drifting from right to left (see picture). What should I look for to solve this problem? I guess it’s hardware. Printer is an ao-101.

Does the first layer evenly print across the entire bed? If so, then it’s more likely that the print is lifting off the bed on that axis. What material are you printing with? Any more details you can share? The Z axis on the AO-101 rarely if ever gets out of square.

I didn’t run a z-calibration print before this particular print, so I’m not totally sure it was perfectly level. However, when the print was done, the adhesion to the bed was very good everywhere on the part. I used abs juice on PET tape. I’m printing with natural abs, 0.27mm layer height, 90% infill. It’s basically the “fast profile” provided on lulzbot.com

I’ve never tightened any belts since I started using the printer 2 months ago, should I look in this direction?

Check if your X belt or pulley is loose.

Can you post a pic showing the top-down view?

Is that what you mean? (see picture)

I might have an answer. I had to reload filament during the print, and I might have touched the glass bed by accident, which would explain what we see.

Tension of x belt seems ok by the way.

The AO-101 uses a captive brass nut for the drive system on the Z axis. It’s free to move along the X axis, to help minimize any Z banding. That nut can potentially get loose if one of the X ends are loose. Examining that would be the last thing you’d want to check though, as it can lead to further work…

Thanks Orias, always helpful comments. I will take a look at that for sure.

I confirm that it’s probably my fault because I printed the other half of my filament spool, and it came out perfect.