3D-Printing issues: Straight Parts printed bent and not perpendicular

1 minute read


After putting my Ender 3 into my improvised cardboard box to print ABS Filament, I noticed that parts that were straight in CAD bent along the Z-Axis. Strangely, it was only on one axis (no motor/driver overheating) and there were no obvious changes. After closer inspection though, I could find out what the problem in the enclosure was…

Bent Part

Printers affected by this issue:

This problem could occur on most enclosed printers, but it is way more likely on belt-driven motion systems and printers that have printed parts on the motion system. On cartesian motion systems, it will be visible on single axis too!

How to detect?

Printed parts turn out to be bent and belt tension doesn’t stay constant. Print bed needs a lot of tramming (leveling) and the nozzle might crash into the bed

Dangers imposed by this problem:

To a certain degree, these inaccuracies can be tolerated. However, at least when you can see them with your eye, the part gets unusable and increases plastic waste and machine time. Furthermore, the printer could loose its mechanical stability and collapse or damage the print surface.


At first, I thought the belt tensioner came loose. However, it was in fact the X-Axis carriage that became soft and introduced play into the system! Due to it being printed in PLA (chosen for its stiffness), it creeps after being exposed to heat radiation from the heatbed and the enclosure.

I am reprinting the important parts in ABS filament to increase thermal stability. Do not print mechanical parts in PLA and safe yourself the troubles of heat radiation!