I am using a Bukobot V2 with black PLA and Sclic3r 1.0. I have tried it at .1 and .2 layer height.
In the process of filling in the first layers, the print head will pass over the old layers, and audibly bump/scrape against the previous layers. I have tried most of the Bukobot presets, and I have tried variations of the settings posted here by James005 http://forum.bukobot.com/index.php?topic=3014.0
. I have also used print head temps of 190-210. I'm not sure what settings to change, I think it's Z Lift, but I tried it and faced a 9 hour build time. What can I try?
One other troubleshooting issue, that may be related, is some parts won't stick to the build plate. The larger the footprint the worse the adhesion. I am using fresh 3M painters tape for every build. Along with bed leveling with a piece of paper so that the print head provides a little resistance.
Other than the occasional bumping, the prints are pretty good. I'm attaching a vase and multi part build examples.