ok so the intermediary etch-a-sketch concept "works", but i'm definitely going to go for the design you came up with, benson: pulley'd ultimaker-2. actually.... reviewing the forum messages the mistake that i made was in *not* following what you originally suggested!

http://forums.reprap.org/read.php?177,767087,780154#msg-780154

putting the 2 belts back-to-back round the idler and GT2, it's now obvious that the inner and outer belts travel different lengths round the arcs... so you get "pulling". whoops.

anyway out with that - i'll begin on the pulley-augmented ultimaker style.

l.