Printrbot anti-wobble.

The basic plastic printerbot frequently produces bands on the sides of the prints which match the z-threaded rod pitch. This is most obvious on prints using .2mm or thinner slices.
In order to find the source of the problem I made custom parts to lock the bearings and rods in place. I also made an external bracing.
The source of the banding appears to be a rocking in the z-motors.
This causes uneven z-lift which in turn causes some layers to be squashed and buldge on the sides.
This is easie