October 8, 2010

Falmouth Turntable - Part 5

Another view of the Manassas turntable from Alexander's book credited
to the Southern Railway Colection. Abdil also has this photo in his book.
The Falmouth turntable is nearly done.

 I noticed in Alexander's book, Civil War Railroads and Models, a photo of the Manassas turntable from a slightly different angle than the photo in the on-line National Archives. I initially thought the photos were the same, but in studying them I realized they were two different shots. Compare it to the shot in this first post  Falmouth Turntable in progress. It would have been nice to have a good side view too, but none exists that I am aware of. Many of the details of the two shots are the same so I surmise they were taken in rapid succession.

From this photo it is clear that the upright posts on the end are inclined and not vertical. I also concluded that the upright posts are tapered. So I cut some fresh uprights on the laser  from 3/16th inch basswood. While I had the laser fired up I cut  the iron end caps (rub plates) too. 

I added the truss rods using 0.032 inch piano wire as it was the only rod I had on hand that was long enough. 

The wheels are also laser cut. They are more cosmetic than functional in the model as the weight of the locos is too great for the plastic wheels. I also did not get them all perfectly aligned, but they do add an intricate look to the model.  I added 3/16th inch thick (tall) rub strips under end of the turntable. These bear the weight and keep it level, while also adding a bit of friction that keeps the turntable in place once it is situated. I laser cut the pit rail from 1/8th inch plywood, with 0.015 inch laser cut strap iron on the top. I painted the pit rail a tan color as I assumed it is either stone or wood. The strap iron is painted rust.


 These two photos demonstrate the turntable in action.  The engine was able to load and unload without problem. The turn table spins easily, but with enough friction to avoid accidental overshooting.


I still need to add some details to the turntable, finish the pit and add the wiring including the auto reverse unit for polarity control.

Now that it is mostly complete, I can conclude that.... it sure is an unusual design.

8 comments:

  1. Boy does that look sweet!

    It really captures the look and feel in the Manassas photo (minus the post battle damage, of course!)and I bet it will turn (sorry) out to be a signature scene on your road. Congrats!

    I don't know how close your turntable is to the layout edge, but MR in the early 50's had an article on hand driving a manual turntable by attaching a plywwood disc to the bottom of the turntable shaft that was sufficiently larger in diameter than the turntable itself that part of the edge of the disc extended through a slot in the facia and was rotated by hand as the turntable drive. I always thought that this was a nice idea for a manual turntable like yours: plenty of leverage to overcome any friction form the rub strips (which would also be pretty reliable pickups if you use a split rail electical set up), fairly precise control from the large diameter, and no giant hand in the scene to snag or create wear on models. Its in my "to build someday" file.

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  2. I plan to operate the turnable by manually pushing it with the my hand. This is in keeping with my manual switch stands and link and pin couplers. I am purposely avoiding electronic or other "fancy" solutions to problems to try and keep the period feel to the layout.

    I did note that the truss rods are prone to popping loose. I glued them on with ACC and if you try to turn the table using them, they can pop off. I am going back and epoxying them on. But otherwise the TT is quite robust and can take the handling.

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  3. Hi Bernie:

    To my eyes the finished installation really nails the time and place. It is just a great piece of work. When I look at the photos of the loco riding on the turntable I can hear the "creak" of the rods and bolts taking the weight.

    On the rods, I think you mentioned that they sit on plates on top of the posts, like the real thing no doubt did. What about either grooving those plates or attaching small strips either side of the rod to create a channel to capture the rod? Some early freight car truss rod installations have a formed rub/locating pad formed like this where the rod passes over what would otherwise be the queenpost cross beam (I am sure there is a real name for this frame piece, I just don't know it) and I wouldn't be surprised if on the prototype turntable the pads were similarly forged or cast.

    What a terrific model.

    Matt

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  4. The rub plates on the tops do have grooves cut in them using my laser. I tried to capture the prototype ones as best I could. I used the laser to engrave the curved surface too. So they have the right profile. In the end I think they came out well. The trick was to taper the posts so that the rub plates were about the right size.

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  5. The rub plates and the whole thing came out really well. I would be happy to do anything close.

    Question on a different topic: is that a curved stub switch in the background and if it is, are there any problems with kinks on the approach rails or where the the approach rails line up with the switch rails?

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  6. Yes that is a curved turnout. And it's on the tightest radius of the whole layout! I made sure this worked before moving on to the rest of the layout. The radius here is 28 inches, which is very tight, but the trains can take it. Elsewhere on the layout I stayed above 30 inch radius.

    I don't have problems with kinks in this turnout. I pre-curved the point rails before installing them, so they flow with curve. See this earlier posting with a video of this section, though it doesn't show that turnout up close. Curve Radius Test Video http://usmrr.blogspot.com/2009/07/track-test-video.html

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  7. Bernie,
    Looking good as your work usually does.

    Bob Harris

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