I am in the process of assembling and tuning a new printer. This one has a 14:1 geared stepper driving the z-axis.

I ran into a problem where my prints were looking squished, like so:

The white cube on the right is in the right range, dimensionally (20mm^3). The blue one on the left is 20mmx20mmx6mm.

Internet searches on this were not helpful at first. There's a lot of discussion about how to properly set your steps/mm for the z axis.

This wasn't my problem though. When I jogged the print head around and measured, movements were accurate. My steps/mm were correct.

Finally, I found a super-helpful post on the reprap forums. My thanks to konwiddak, jamesdanielv, and the other contributors on the thread.

If you are having a problem where your printer movements are correct, but actual printed parts turn out way too short, try the following (especially if you have a geared stepper driving Z):

• Tune down your z-motor current and make sure your controller board is properly ventilated.
• Set a low feedrate for the z-axis, 2 or 3 mm/s.
• Increase your z max acceleration.

Good luck!