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Dave's Park!

Dave's Park!

Sector Plate

The sector plate is a unique solution to a sticky problem. From the earliest versions of the track plan I was trying to find a way to reverse a locomotive. Before settling on a hill and tunnel as a way to hide the trains I had tried to include an underground loop but either way there was never going to be room for a wye and I did not want to turn the museum spur into a reversing loop.

After a while I stumbled upon a few British web sites featuring micro layouts and that is where I first found the sector plate idea. Unlike those sector plates, which were very elementary in design, I wanted to build one that would look like it might if something like that actually existed in the real world. It was with that in mind that I started collecting all the photos of turntables that I could find. I essentially designed the table portion to look like half of a turntable.

Shortly after deciding to build the sector plate project a fellow modeller was able to find on Google Earth a proto-type of a sector plate in the US mid-west, at a small independent car repair facility. It just goes to prove that for just about everything we model there IS a prototype.

The first step, as always, was to draw a plan that I liked. When that was refined, I started working with wood. I used a hardwood paint stick as the material for the table top. The rest of the material was either pine or balsa.

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Instead of using a single rail as most turntables would I used a piece of regular flex track and two plastic wheelsets. The only reason I chose to do this was because these were the materials I had at hand. The blocks that hold the axle points were cut, sanded and small holes drilled for the points. The axles were aligned with lines drawn from the pivot point of the table to infinity. You can see this offset spacing in the fourth photo in the group below. This was done so that the wheelsets would track properly on the curved rails.

Hindsight is always 20/20 vision. There are a couple of things I would do differently if was to build this unit again. The way I have the wheelsets installed in the blocks does not allow for easy removal of the wheelsets should I ever decide to replace them. I had thought about using a truck but the axle alignment would not be right for that tight a radius. I would however try to make one of the blocks removable for the purpose of replacing the wheelsets.

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With the wheelsets installed I added the sides and dressed them up using balsa strips. I used a piece of brass tube for a pivot so the wires from the rails could pass through to the underside of the layout for connection using quick-disconnects so the table can be removed easily. The brass tube has an inside diameter big enough to allow the disconnects to pass through. A washer was glued on using epoxy to provide a wear surface. It was time to work on the sector plate pit.

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I took a measurement from the pivot to the leading edge of the table, spaced the back end of the table for clearance and drew the curve of the outside edge of the pit. Everything else lined up from there. I took the flex track and very carefully starting shaping it. It is much easier to work with a long piece and then cut it to the proper length after it is shaped.

The pit floor was drawn to the dimensions on the town plan and cut. Side walls were added accordingly. The height of the side wall was determined by setting the wheels on the track and measuring to the top of the table. I decided to make the walls 1/8 inch shorter than that measurement to allow for some height adjustment when installing the unit. This would be easy to do because it was to be installed in foam board which can be cut very easily. Side walls were made of a tongue and groove patterned styrene.

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To help hold the track in proper alignment I added a spacer strip to which I pushed the ties up against. The strip was cut out of picture matte, the same material used for the top ledge. A wear surface for the pivot was made from the same material and brushed with two coats of polyurethane to give it a bit more durability.

When adding the strip it is important to make sure that the curve of the track follows through at the ends. I squared mine off at the center line of the table, not thinking about the consequences, and had to make some adjustments after the fact. The track was glued down and the top ledge was added to the side walls.

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The rest of the project went very quickly. The track was laid and wired. A control shack was added to the side making sure it cleared the top ledge of the sidewall. It was made of the same styrene as used for the sidewalls. The safety rails were made of fine craft wire. The whole unit was painted, weathered and installed. To ballast the bottom of the pit I brushed on a coat of full strength white glue, covered it with ballast, tamped it down and vacuumed up the excess after it had a chance to thoroughly dry. The addition of an Imex storage shed and outhouse completes the deal. The only detail remaining to be added is a yard for a service truck or two. I am very pleased with the results and it works as great as it looks! A control cable could be added but I am satisfied to operate it manually.

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