This is a derivative of RichRap's 3DR Delta printer, but redesigned from scratch to be printable from a Printrbot Simple, and to use it's parts in order to build this printer.
My 3DR simple is about as tall as is practical. It has a max unclipped build cylinder with a height of 400mm and a diameter of 140mm. (It homes to Z=~450mm) Any taller and you end up having oscillation issues.
What maximum height of printer you are recommend for 20x20mm extrusion and 8mm rod? BTW, http://www.thingiverse.com/thing:646708 ! What you think about?