As promised, these are the plans and photos showing how I constructed and installed my hand-operated turntable. I want to stress that none of this comes from any idea of mine; as mentioned in a previous post, this setup is based on a 1951 Model Railroader article. Likewise, the wiring scheme comes from an installment of the"From Pillar To Post" series that ran in the same magazine in 1949.
Photos 1, 2
These plans are pretty self-explanatory. The only thing I'd point out is that my particular turntable design is based on prototypes where the pit rail wheels at each end of the turntable are all but concealed under the turntable bridge structure. I at first considered adding the wheels, but since they wouldn't really be visible, I left them off for simplicity's sake.
Photo 3
Underside of the control disk, which was cut from a piece of particleboard.
Photos 4, 5
Overall views of the turntable, approach track, and the three roundhouse tracks, each of which are independently powered.
Photo 6
Underside of the turntable pit.
Photo 7
The turntable bridge.
Photo 8
Closeup of the wiper, constructed from 1/4 inch-wide brass, and bent to provide a "spring" effect to ensure good contact with the pit rail.
Photo 9
Pit rail, including one of the gaps; the gaps will later be filled by small pieces of rail glued into place. The coating of glue will act as insulation.*
Photo 10
This is an "armstrong" turntable, plausibly still in use in 1947 since it serves only a small, three-stall roundhouse.
*Nov. 29 note: I wound up using small pieces of rail-sized stripwood to ensure the gaps remained insulated...safer than using rail, even with the glue.