the biggest issue with the dual Z motors is getting the X carriage level, took a little tweaking and measuring from the top frame rail down to get it just right, but so far so good.
On this version (may be the same on other Prusas?), the X assembly rides on a single nut on each side with the weight of the assembly keeping things in place. simply lift the assembly, adjust the nuts, and set the assembly back down over the nuts.
We had more issues with the extruder wanting to jam than anything else (not thrilled with the design of this thing at all - looking into alternatives - will be the first upgrade). Have had it apart several times in the first full day of trying to print anything with it. Turns out the set screw on the drive gear was causing us issues - it was catching on the filament and jamming. Flipping the drive gear so the set screw is closer to the motor made a big difference.
Have been tweaking the vref for the motors - X was getting a bit hot, now have it dialed in to where it is running pretty cool. Y is a huge motor compared to the rest, and has been running nice and cool from the start, but will be tweaking it to run at optimum voltage. Z motors could stand just a little tweaking yet, they dont get hot, but do get lukewarm to the touch...
It is weird, but nothing shows up in the EEPROM screen in RH, so all steps/mm changes have to be done manually with g-code - had to go look up the codes to make adjustments, LOL. then had to dig into the firmware to see what the default steps/mm were set at - needed to tweak the extruder steps a little - it was under-extruding by about 12mm.
Also have some minor backlash issues that need to be sorted out (perimeters and fill not quite meeting on the first layer) - not really sure how to go about that with the way the belts are attached (no adjustment screws, uses the a tension spring?) may need to look into different mounts for the belts, too...
ah the joys of tweaking a new printer. LOL
SD4 #1 & #2 - Lawsy carriages, E3D v6, Rumba controller board, mirror bed plate, X motor fan, upgraded PSU & Mica bed heater
SD4 #3 - in the works ~ Folgertech FT-5, rev 1
Printit Industries Beta Tester - Horizon H1