Printer does not move to build plate when starting new part

Hi all,

So I just got my first 3D printer working, and it's printing fine right now for single parts.
However, when I want to print multiple individual parts, as soon as the printer starts the second part, it does not move to Z-home, but starts printing in mid air.
This results in a bunch of filament curling up randomly, wasting my filament and not giving me the desired part.

Anyone who had the same problem? I use a Prusa i3, running on Megatronics with Marlin, with Slic3r as the slicer, and Pronterface as the printing program.

Thanks!

Do you have a good reason to print parts consecutively? Usually I print multiple parts at the same time, layer by layer.

The reason for the mid air prints might be the start/end gcode of slic3r. I believe it switches to "relative coordinates" at the end, but doesn´t automatically switch back to "absolute coordinates".
Just add :
G90 ;absolute positioning
in the beginning of the startcode and try again with two simple parts.

-Olaf

Got it working by turning down the Z axis speeds. Apparently the speeds set in Marlin were too much for the steppers to handle. It moves to the build plate fine now. Thanks!