Get the bed level so we can print raftless on the Up 3d printer

[amcewen]

If you try printing without a raft on the blue Up 3d printer, you get a variety of levels of adhesion to the bed, and your print will generally fail.

That's because the bed isn't quite level. http://www.thingiverse.com/thing:39430/#instructions seems an interesting approach where you level the bed while it's printing. We should try that to see if we can get to consistent, raftless printing.

[DefProc]

I've levelled the bed on Violet (the blue one), and it's printing much better that this morning.