SquareBOT addon (Counterweight system)

This addon for my SquareBOT project allows to use a conventional NEMA17 motor (without a gearbox) for a vertical axis (Z) to reduce a cost of construction.
The counterweight system compensates for the weight of the X-axis. My load (plumbum ingot) is 975 grams. I printed two slides for this load with trimmer nylon. Also I've been using this nylon filament as a hawser.
I had to print the new belt fixers.
The SquareBOT project: http://www.thingiverse.com/thing:480008