Cool ! - what is this large gizmo with bearings ?  What has your experiences been with the Sabertooth ? fun hardware WOOHOO !   I've built my own custom H-Bridge motor controllers before, but after months of frustration and too much work for return, I finally decided to buy a Sabertooth - heard good things about them..  I know the guy who makes OSMC which is really an amazing controller - but mebbe a little overbuilt for what I need.