After having backlash problems on my RepRap Mendel X-axis and getting sick of the awkward round-4-corners belt path, I decided to give it a re-design, in the hope of shortening the belt to take up some slack while simplifying the construction.

These brackets make the belt-path compatible with carriages intended for Prusa Mendel. I have included an adapter bracket that allows it to still be used with the original Mendel X-Carriage when necessary, however the idler bearing and pulley need to be spaced quite far out from the plastic parts in order to keep the belt parallel to the X-axis, with a full nut and a washer or two in the case of the bearing.
I hope someone will design something like the OpenX Carriage (http://www.thingiverse.com/thing:6278) but compatible with this, so that a 624-bearing-based carriage can be used with the Prusa-style belt-path, that is if I don't design one first.

I have also included an optional second idler bearing bracket to go directly next to the motor bracket, so that the belt turns slightly less of a sharp angle as it goes round the pulley, hopefully reducing belt wear, though I really don't think it's necessary.
The big circular holes in the motor & idler2 brackets are there to allow ventilation around the X-motor, so that PLA parts don't heat up too much. (I wanted test parts to be biodegradeable in case I messed up)

N.B. I have updated the files for the main brackets at either end as I found a couple of weaknesses in my first prototypes where I cut away excess corner material too liberally and found that the slots for m3 captive nuts shrank more than I thought they would, making it difficult to fit them. They should also be easier to print now.