Answered Drv 8825

You need to change the Z axis steps, use M503 (first line of output) to see that the current steps are then use M92 Znnn to set them. Usually it is off by a factor of two, so try doubling them or halving them then see whioch one it is to put in firmware, recompile and reflash.

 

If you have an LCD you can see it there too. There is a menu choice to see what it is set at.

 

http://marlinfw.org/docs/features/lcd_menu.html

Motion menu under Steps/mm

 

Stock drivers are Allegro 4988 about the cheapest (after years of use) drivers you can get. Same as most RAMPS based printers. Robo has used these driver chips on every printer so far, including the new R2 / C2.

 

A little more detail here: http://community.robo3d.com/index.php?threads/stepper-driver-calibration-information.6466/

If you search the forums you will find some threads discussing the advantages of one over the other. Personally... no real difference noted in those two. There are more modern approaches that are an improvement, but not for 'free' (in the sense that they will take effort to employ, you can't just drop them in).