I initially had a problem with the Z-axis dropping when using V-Carve Pro. I thought it was from losing stepper power, but it turned out that it was actually due to the rapid feed rates set by V-Carve Pro causing the Z-axis to lose steps. Since it never reached the intended height on rapid raise, it would plunge farther into the board when it came back down, making it seem like the Z-axis had lost power.
I added the following commands to the Marlin post-processor found in this forum (original thread for Marlin_mm-test5.zip).
In the header, I made declarations for global max Z acceleration and max Z travel speed. With the lower limits, I have had no more lost steps and no more Z drop.
Want my updated post-processor file for V-Carve Pro? Shared from DropBox.
Marlin_mm_Slow_Z.pp