Here is the rotary base. I machined a disk 8" in diameter and 1" thick from nylatron. I then cut out the internal shape and atached a Gates notched belt to the internal surface with Gorilla glue.
The second 8"x8" nylatron blank was machined to hold the disk. The pinnion placement was measured and drilled for a perfect alignment to the internal ring gear.
The disk sits on the base and turns very smoothly. The pinion has 12 teeth and the belt 116 teeth. This gives me a ~ 9.66 to 1 reduction.
A window regulator motor is connect to the pinnion by a coupling.
2
Step 2
The elbow joint is complete. A stainless steel cable will control the position and remove weight from the outer end.
The inside use of toothed belt is nice idea. One has to be careful with belt load rating - typical number of teeth engaged is way higher (5...6), so there is need to downgrade maximum allowable load accordingly.
The inside use of toothed belt is nice idea. One has to be careful with belt load rating - typical number of teeth engaged is way higher (5...6), so there is need to downgrade maximum allowable load accordingly.