I posted more info on my website at http://brainright.com/Projects/FourthAxis/, including a Part 1 video of the build and details of the components I used. Part 2 will be coming soon.
Although I am using it with the new Modular CNC Controller that I built, the design should work just as well with the original Shark controller box because the stepper motor is similar to the Shark steppers. This unit should have much higher angular precision and rigidity compared to belt-driven 4th axis units, which is perhaps not all that important for routing wood but I also plan to use this for machining aluminum parts on the Shark, and on my milling machine where the high accuracy and rigidity will be important for applications like gear cutting.
