Unresolved Skipping layers.

http://community.robo3d.com/index.php?threads/how-to-cura-setup.4169/

That should be a good start. You can either copy in the g-code to your software of choice, or just install cura.

 

Ok. Thanks very much!

 

I know this is a little old, but I ran into the same issue, I have my two cents, since this says "unresolved".

I am assuming it is one of a few issues, and I am still trying to address it myself. Interestingly enough, one possibility not discussed here (which would also explain inconsistent heights) is that the PLA reel itself is too tightly coiled, getting stuck, and when this happens the stepper motor will advance the knurled bolt and actually start climbing up the z axis, free of the supports. I have seen this happen, and it happened with particularly stiff and troublesome reels of PLA where the coils are wedged so tight they almost seem sticky. The coil in question for me was actually the test Blue that shipped with the R1+, but a quick way to fix this is to just take the whole reel and firmly give it a few whacks on the side, and jiggle up the individual lines on the spool with your fingers loosening them up. PLA has problems if it absorbs too much moisture, so make sure to seal up the individual reels when you are not using them with anti-dessicant. If the PLA gains moisture and then dries out, it becomes much more brittle and even weaker for tensile strength.

I have also watched the printer visibly skip layers at random heights when I forgot to plug the fan back in, so this really emphasizes how important proper cooling is on the board and through the unit. If I suspect the cooling, I may adjust my fan solution in the future, though I am not sure how.