I have Anet A8 where I have changed the controller from the original to RAMPS 1.4 running Marlin 1.1.1 and ran into some strange issues with my Z axis.

Doing calibration (10 mm cube, 10x10x20 mm, 10x10x30 mm) I am dead on the mm on the Z axis. (10 mm, 20 mm, 30 mm) But when I print a part that is supposed to be 24 mm high, it comes out 27 mm high.

Went back to print calibration 10x10x30, and Z axis is dead on 30 mm again.

Also printed a bracket that was supposed to be 240 mm high, ended up close to 270 mm.

I am doing the same layer heights for all the prints (calibration cubes and otherwise). Starting with a 0.2 mm first layer and then 0.1 mm on all other layers. Using RepetierHost v. 1.6.2 with Slic3r v. 1.2.9

Anyone experienced something like this?

  • $\begingroup$ Are you using the same layer heights for all prints, or do you have a different height for the calibration cubes and for the other prints? Perhaps your Z axis is having trouble stepping accurately with a different layer height. $\endgroup$
    – mbmcavoy
    Jun 13, 2017 at 18:24

1 Answer 1


This was a comment from the OP, which effectively answers their own question:


  • Installing new Marlin 1.1.3;
  • Changing the Maximum Acceleration on Z down to 20, and;
  • Changing Acceleration and Retract Acceleration down to 1000.

I have now a printout that measures 24.65 mm (0.65 mm higher than it should) and good enough for me to say, this is OK.


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