Screw Together Belt Tensioner

This is a belt tensioner with a screw on cover. I have been using belt tensioners like this:

http://www.thingiverse.com/thing:38970

for quite some time, but they always seem to break apart after a few months. The break was always on the back side along the groove. By adding on a screw on cover it should make this tensioner considerably stronger. I also made the walls thicker than the ones I was finding on here. The screw holes are places so that they do not get in the way of the belt trave