Been some 'boring' days lately, boring out and turning the spindle and hub for the cab rotation bearing assembly. The spindle/hub are steel, the washer and nut are brass (just since I had some offcuts the right size, otherwise would have been steel too). The gear was bored out as well to fit the hub, there will be a gear motor inside the cab by the boom base driving a spur gear against the big gear. The big gear and hub stay stationary with respect to the track frame, and the spindle/cab spin around on that. All fits well, and the hub spins freely without play - no grease in the roller bearings yet, just since it will be handled so much for a while. Here are some pics of the top/bottom of the assembly.
Bottom view, the end with the nut will face downwards in the final assembly.
Top view - the inner spindle will bolt to the cab floor.
With these parts done, now I can lay out and start drilling the patterns of holes in the cab floor for the spindle as well as the boom base and its drive motor....