07-23-2009, 11:01 AM
Josh, I think I would still mount the Modesto Yard on an elevator and forget the helix. You could build the yard bench work with thin plywood and foam for light weight, and then use a frame work made of aluminum angle to strengthen the entire assembly while holding the weight down. Install 2x2 stringers vertically on your wall studs, and mount the heaviest duty, ball bearing drawer slides vertically to locate and guide the yard up and down. Install a 3/4 inch threaded rod going through a nut secured to the yard benchwork. Put a pulley on the bottom of the threaded rod and a pulley on the end of a 110 volt ac motor mounted to the wall below the bench work. When the motor turns one way the threaded rod carries the yard up to the second level, when it is reversed the threaded rod carries the yard down to the lower level. Put a spring loaded switch below the bench work at the bottom and another one above the bench work at the top that is wired to the motor switch through the normally closed contacts at each end of the travel. You would power the motor through a double pole, double throw rocker type switch. When the yard is coming down and actuates the switch at the bottom, the switch would open shutting off the motor and shifting the power to the other side of the rocker switch. That would stop the yard from moving down further, but allow the rocker switch to start the motor in the opposite direction. The switch at the top of the travel would work just the opposite stopping upward travel but allowing downward travel. Make the two limit switches adjustable to allow you to align the yard with the layout. If you don't want to be switching high voltage, you could wire the motor through a contactor with the contactor activated by relays energised by the rocker switch.