Printed figure Z-size too small

Hey guys,

i´ve a rigidbot with the latest Marlin RC6 firmware- and upgraded to a sainsmart-2-in-1 mainboard.
I connected both Z-axis motors to the one slot on the mainboard for the z-axis-stepper.

I´ve tested the printer with pronterface- sending a command to move 10mm on z, and measured it- and it was 10mm...
Really strange- don´t know why only the print fails, but the printer was moving correctly on the z-axis...

I´ve set the Z-axis stedriver to 1/16 steps (Z-Trimpot to 0.84V) and these are the firmware configs:

echoteps per unit:
echo: M92 X200.00 Y200.00 Z1600.00 E73.00
echo:Maximum feedrates (mm/s):
echo: M203 X500.00 Y500.00 Z5.00 E25.00
echo:Maximum Acceleration (mm/s2):
echo: M201 X800 Y800 Z100 E10000
echo:Accelerations: P=printing, R=retract and T=travel
echo: M204 P600.00 R1000.00 T3000.00
echo:Advanced variables: S=Min feedrate (mm/s), T=Min travel feedrate (mm/s), B=minimum segment time (ms), X=maximum XY jerk (mm/s), Z=maximum Z jerk (mm/s), E=maximum E jerk (mm/s)
echo: M205 S0.00 T0.00 B20000 X8.00 Z0.40 E5.00

Can anybody help me?

There you can see the print result:
[goo.gl]

If in pronterface your printer moves the right amount, you need to check the scale settings in the slicer, they might not been set proportional.