Prism Z belt springy idler

This is a an idler for the Z axis belt of your Prism Reprap (design by by Buback)

Its two primary purposes are : to be able to use a longer closed belt, like found for instance in original Mendel belts set, and to dampen the wobbling given by printed Z pulleys (sometimes a little oval).

The side effect bonuses are : better belt path with more teeth engaged on the driving and driven pulleys, easy belt tension adjustment.