September 27, 2010

Falmouth Turntable in progress

I nearly finished all the wiring in the main room this weekend, but I need 3 Frog Juicers to wrap it up. I ordered two more Hex Frog Juicers (enough for 12 turnouts) so I can finish the wiring here and be ready for the yard at Aquia Landing.  Even with incomplete wiring, I ran the Engine Haupt with a short train to test track. Now that the double crossover in Falmouth is operating with auto reverse units on the frogs, I discovered that some fine tuning of the turnouts was needed.

      This turntable at Manassas served as inspiration for my
Falmouth turntable. Note the lightness of the rail, and the
crude level of  construction. It is hard to tell if there are stringer beams
under the ties and rails.  I assumed there were.

So with wiring on hold, I started construction of the Falmouth turntable.  The turntable is needed at Falmouth to turn locomotives so they can make the return trip nose first.
The turntable is loosely based on the prototype at  Manassass seen in the famous photo after Jackson's Raid in 1862.  Edwin Alexander made a set of plans based on the photo, but something about his plan didn't look right to me, so I modified the design to reflect how I think it may have been.

I used laser cut 3/16th inch basswood for the main structure and sugar pine ties from Mt Albert.  I added many Tichy NBWs to simulate the bolts holding the beans together. However, I did not simulate the laminations of the beams. I still need to add the truss rods, wheels and other details.

The pedestal separated from the shaft.
The pedestal will be glued to the pit floor. 
The shaft is a set of 1/2 inch and 7/16 inch Evergreen styrene tubes that telescope tightly together. I epoxied the tube to the center hole in the turntable bridge.

To make the conducting bands, I soldered 26 gauge wire leads to strips of 0.005 inch shim brass.  Then I drilled holes in the shaft, ran the leads into the holes. Next I wrapped the brass bands tightly around the 7/16ht inch shaft and quickly soldered them without melting the plastic.

Close up of the turntable shaft
With this design, the turntable shaft can slide into the pedestal. The pedestal will be glued to the pit floor.  If all goes to plan,  I'll be able to drop the turntable through the hole. Then add electrical wipers to the bands. I'll use a digital autoreverse unit to control the power to the rails.

This is a manual turntable, so I will not be using an indexing system. It's "armstrong" all the way.

It just occurred to me that this is the first turntable I have ever built either from scratch or kit. I had a Walthers N Scale turntable, but never installed it.

I am keeping my fingers crossed!
Overall view of the 12 inch turntable in its approximate location before I drill the shaft hole
and hog out the styrofoam.

2 comments:

  1. Did I read that right? You only need a 12" turntable in O scale?

    Bob Harris

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  2. Yes, it is 12 inches long. I am reconsidering the design as I think about it some more, but the revised design will remain 12 inches long.

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