Tuesday, November 13, 2012

The Shumala extension

I have long planned to make an extension to my town of Shumala, so that the overall arrangement of it would be kind of an L shape. This post describes the early steps in building this extension.
     There is a brown bookcase along the end wall of my layout room, with its top below the level of the layout. Accordingly, I screwed some segments of L-girder to the top of the bookcase (this would be easily reversible if ever necessary). Each riser was then raised in height with a second segment of L-girder, glued back to back with the first ones. The back-to-back arrangement maximizes access to the screw attachment points, if I ever needed to do that. To determine the final height, a correct-thickness board was placed atop the clamped pieces, and carefully leveled. Then these second pieces were glued and re-clamped, at the final height needed for these risers, while glue was still wet. Here is how it looked when done.


     I cut a piece of 3/4-inch plywood to fit this space, and checked its fit and height to make sure it was okay. I have occasionally been asked why I use 3/4-inch plywood, and I usually give Tony Koester’s response to the same question: “because I couldn’t get 1-inch plywood.” Structural stiffness is important in layout performance, and thicker plywood is an easy way to increase stiffness. Here is the new plywood piece in its place, at left.


You can see that there are a couple of irregular pieces of plywood at the right of the new board for the extension, where the main line curves away to the right. This entire area needs to receive a surface layer on which to lay track, for which I like to use Homasote or its equivalent. (“Homasote” is a trademarked name for a construction board made from recycled paper by the Homasote Company; you can learn more about them at their website, at http://www.homasote.com/products/ .)
     My next step, then, was to cut some Homasote pieces to provide the level ground surface. Some pieces were simple rectangles, but others, at the right in the photo above, had to be irregular. I made a template with a piece of newspaper, and cut and trimmed the paper until it matched the shape I wanted. I then used a utility knife to cut out the Homasote piece, following the pattern. Here is one pattern I used:


The piece cut from this pattern is shown below, in its approximate position on the track board, though not yet glued down. The mainline track is at right.


     This piece, and others, were arranged so they have joints in quite different places than the underlying plywood. (Compare the photo above to the one above the pattern, to see how this overlaps.) I glued these pieces down a couple at a time, using yellow carpenter’s glue. I generally clamp the materials when gluing Homasote to plywood, to ensure a good bond and a smooth surface. Here is some of the gluing in progress, with a generous number of clamps in use (note wood clamping pads to minimize indentation into the Homasote):


When gluing was complete, my new extension area looked like this (obviously some of the Homasote pieces were prepainted white on one side).


     Some gaps and cracks between Homasote pieces were present, and those areas were filled and roughly contoured with Sculptamold (a product of American Art Clay—you can see their entire line at: http://www.amaco.com/ ), including aligning the new diverging track ballast edge, as seen here. I just use a putty knife for these kinds of rough contours.


Once I have general contours with Sculptamold, I like to refine the surface with smaller tools and with a much finer-grain papier maché, widely available from taxidermist supply houses. My favorite is Brandt’s Compound, from Robert Ruozzi of Irwin, Pennsylvania.
     I will describe track arrangements, scenery, and industries for this layout extension in subsequent posts.
Tony Thompson

2 comments:

  1. Did you attach the plywood to the risers?

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  2. No. In benchwork like this, where the Homasote IS glued to all the plywood, it's not going anywhere, and without a connector like a nail or screw, sound transmission is greatly reduced. The benchwork will be sound-deadening. I used the same approach successfully in my Pittsburgh layout (only in places where it worked structurally, of course).
    Tony Thompson

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