The Legacy Dome Motivator

The release of my design plans and assembly for the NextGen Frame generated some interest in having a version of the CS:R Dome motivator for Legacy Styrene Droids. Once I had some free time after the release of the NextGen frame I started working on a version of the Dome Motivator that could be used on either one of my Eggcrate Frames or with a Styrene Droid built with 
Dave Everett's plans. One design should work for either design since the rib spacing is driven by skin featuers that are the same for both designs. Here's the result of that design work. Before you start, I suggest you review the Dome Motivator instructions in the NextGen Frame.

Left: the parts panel is smaller and all of the parts are located inside of the large internal gear. Those are the spur gear, the motor mount & the mounting bracket. The curve on the mounting bracket is slightly smaller than the Frame OD. While the curve on the motor mount is slightly smaller than the top ring ID.

Above: the motor bolts into the motor mount. the spur gear is mounted onto a pololu hub.
Right: the motor mount is clamped to the mounting bracket.

while you can't see the clamp here, use one for the initial fit in case you need to trim either curved edge.

I'm cheating here, but there should be enough clearance that you can clamp the mounting bracket to the top ring from the inside in case you already have skins installed. It's designed to fit in the gap between the ribs on either side of  the rear of the droid.

I also measured the height of the top of the spur gear relative to the top of the motor mount so it could be preset.

Left: with everything clamped in place it's a good idea to test the assembly by running the motor. While it's a 12v motor, a 5v supply is fine for the test.
Above: while a move clip would be nicer, the dome ring is moving (slightly blurry) and the spur gear is moving faster (more blurry)

The motor bolt mounting pattern was designed for the Pololu 37D line of gearmotors but it should also work with the Jaycar YG2738 gearmotor. As far as I can tell, they have the same bolt pattern.

The first prototype of the Legacy Dome Motivator was tested by Kevin Roche (kmr926) and posted on his forum build page. Thanks Kevin! The bearing he had is the VXB lazy susan bearing. The Dome Motivator was designed for the Rockler Bearing. However, I was able to get mounting hole information from Vxb and I've modified the prototype based on Kevin Roche's feedback so that it can accommodate either the Rockler Bearing or the Vxb bearing mounting hole pattern. To do so I added 1/4 inch to the diameter of the internal gear since the Vxb bearing's mounting hole had a larger diameter than the Rockler.

You can download .pdf and autocad .dwg files: Click Here