Ender 3 nozzle gets closer and closer to the previous layer as the print progresses I'm trying to print a lithophane with my Ender 3, but the nozzle gets closer and closer to the previous layer,  layer after layer.

I thought that what was causing the problem was perhaps a gear lock due to the fact that the Z rod wasn't parallel to the vertical axis, but after fixing it the problem remains.

The bed is super planar and perfectly levelled and, in fact, the first layer comes out perfectly.
Extrusion is also okay. The printer seems fine in all aspects.

It seems like the seriousness of the problem is proportional to the number of layers, just like the printer is losing a fixed height by each layer.

I've ruled out the possibility of wrong calibration of Z steps because after measuring a cube of 12&nbsp;cm of height and telling the printer to raise 12&nbsp;cm the cube fits perfectly under the nozzle with the levelling gap (so perfect calibration).

What do you think may be the problem?
Finally I've found the damn problem: Adjustable rollers of all axes were flat on one point making layers to shift in all directions.

The effect was less visible on the X and Y axes but it was more notable in the Z axis as the flat part was right from the start of the print. I think that flat part was making difficult for the Z axis to move upward, and making my prints fail when printing at higher resolutions (I guess the finer the displacement the weaker the torque).

It seemed to me that the nozzle was getting closer to the previous layer but instead it was resting (or barely moving) on the flat part of the Z right adjustable roller first and then on the other adjustable roller of the same axis.

To diagnose the problem disable the steppers and moved the axes manually and feel if there are notches, so to speak, in various spots on every axis.

The solution is to replace the rollers with new ones and to not close them too tight otherwise they'll deform over time.