Construction methods
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Introduction
You have decided to build a model railroad layout, but you know that you are going to want to add to it in the future, to make changes as you acquire more equipment and learn more about the hobby. Will the support structure you construct for your model railroad be useable for future development, or will its future be consignment to the scrap pile? Happily, if you choose your construction method carefully, your structure can live on and provide the foundation for much railroad progress.
Model railroad support structure, commonly called benchwork, can be constructed in a wide array of configurations. This chapter will look at the best designs, starting with the most efficient, and will look at some innovative techniques modelers have developed to speed construction or to adapt their railroads to particular spaces and conditions. Have fun, and turn your imagination loose. Innovation is a key part of design. Think of how these techniques can help you achieve the model railroad you are dreaming about.
L-Girder Benchwork
You have decided to put a mountain range where the freight yard is located, a wide city scene where only a narrow gorge is modeled, and a new branch line where only scenery currently exists. Do you have to completely rebuild the benchwork? No, not if you built your original layout using L-girder construction. The late Linn Westcott, longtime editor of Model Railroader, developed this benchwork technique specifically for model railroads. He wanted to provide sufficient strength to support trains and scenery and to provide flexibility in constructing the physical features of the layout. He also wanted a benchwork system that was economical to construct, using as few resources as possible. That he achieved that goal is attested to by the reported thousands of layouts built using this technique.
L-girder benchwork gains its name from the backbone of the structure, a piece of 1X2 wood strip glued at right angles to a 1X4 wood strip, forming an L-shaped beam with a web and a flange. The L shape counteracts the tendency of the wood to warp towards its wide side. Linn Westcott originally intended that the pieces of wood would be held tightly together by screws while wood glue (aliphatic resin today) cured. The glued joint is far stronger than the screwed joint, and drill bits can be instantly dulled by encountering a hidden screw, so he suggested removing the screws after the joint cured. This screwed-together-until-joint-is-cured-then-screws-removed recommendation applies to all bonded joints used in L-girder construction. Many people prefer to leave the screws in, feeling that they add to joint integrity. From an engineering standpoint, the glued joint is far stronger and does not need the screws for support. However, if leaving the screws in place makes you feel all warm and fuzzy then, by all means, leave them in place. You can purchase wood milled in a L shape, but it is prohibitively expensive.
The L-girders are attached to, and transmit their load to, conventionally designed legs. The L-girders provide a platform to attach joists, which define the shape of the final terrain. The girders can easily span twenty feet. Loads applied at center span are transmitted to the legs by diagonal braces running from the middle of the L-girder to the legs. The width of the leg set can be varied to provide stability for whatever width of benchwork you are building.
Joists are mounted at right angles to the L-girders and are attached from the underside of the L-girder flange. Spacing is nominally at eighteen inches, but can be set closer to meet your particular design needs. The length of the joists can be varied to meet your particular design needs as well. Risers are attached to the joists where needed to provide support of roadbed, yard areas, town plats and scenery features. Risers are attached to the joists where needed to provide support of roadbed, yard areas, town plats and scenery features. Roadbed, the support for your trackwork, is attached to the risers. Many people use the "cookie cutter" approach, cutting the exact shape of the track contours out of plywood and attaching each piece to the risers. Others use a technique called spline roadbed, where thin strips of wood are bent to the track layout; spacers and other strips of wood are bonded to the original strip to complete the roadbed section. Homasote or other similar wallboard material is bonded onto the roadbed to form the base for track laying. (Be sure to read the section "A Much Quicker Way" to see an alternative to this method).
As you can see, all of the variables in L-girder benchwork can be manipulated to meet your particular requirements, and that is its great appeal. This construction method allows you to build to meet whatever space is available or to whatever shape you want your layout to have.
More detailed information on using this construction technique can be found in Kalmbach Book's recently re-released book Model Railroad Benchwork by Linn Westcott.
Open Grid Construction
Afraid of Uncle Harry careening into the side of your layout? Do you want extra strength at the edges to support control panels or other electronics? Then open grid construction may be just what you need.
Open grid is a close relative, the first ancestor really, of L-girder benchwork. Open grid, sometimes called butt-joint construction because of how the joists are attached to the frame, shares a common leg design with L-girder. The main difference is that a rigid perimeter frame defines the boundaries of the benchwork. Joists are attached between frame elements to provide strength and to provide a place to attach risers and to support scenery elements.
The main disadvantage is that this technique is somewhat less flexible when it comes to creating irregular edges or to making major changes in benchwork configuration. The main advantage is greater strength at a potentially vulnerable point on the layout. Robert Felch used the inherent strength of open gird design to overcome a space problem he had with his layout. In an article appearing in the October 1995 issue of Model Railroader, Robert shows how he attached skids to his benchwork to allow it to be moved to enhance access. The strength afforded by the perimeter frame allows him to pull and push on the benchwork. This article also offers an excellent photo of a well-constructed open grid bench in the construction stages, so you can see the relationship between the frame and the joists.
Open Grid - Variations
Does the idea of a solid frame with stable legs appeal to you, but you think open grid construction is only for building room-sized layouts? Don't despair, this technique is amazingly flexible, and smaller applications are easy to design.
Starting in the September 1996 issue of Model Railroader, David Barrow showed how to build a bedroom-sized version of his Cat Mountain and Santa Fe railroad. David uses what he calls "dominoes", sized 18"X48", to construct a thirty-two square foot railroad that can be expanded to any length desired. He uses 3/4" birch plywood cut into 1X4 strips to build his benchwork, yielding superb fit, finish and dimensional stability. The basic design is a perimeter frame with solid legs. Because of the relatively small size of each domino, the bench is covered with plywood to support the railroad and scenery. Grid cross members can be added to support particular scenery effects desired.
Robert Smaus authored as series of articles that used a similar construction technique. Starting in December 1990, his Port of Los Angeles project railroad appeared in Model Railroader magazine. He demonstrated how small framed layout sections, similar to David arrow's dominoes, could be supported in different manners depending on how the layout was to be set up. He even demonstrated how such a layout section could be built on a tea cart-like structure that would allow it to be moved around your residence.
A Much Quicker Way
Many modelers spend years building even moderate-sized layouts because of the amount of carpentry work required. Fabricating L-girders, legs, and other structure consumes time that could be better spend operating trains. Lee Nicholas of Corinne, Utah, tore out half of his 30X33 basement layout 12 months ago; the two new peninsulas are back in place, track is laid, scenery is completed, and trains are running in regular operating sessions. How did he do all of that so quickly? First, he didn't just accept someone else's suggestion as to what is the best way to build. Second, he looked at methods and materials that other people were not using and sought ways to make them work. Innovation and unconventional thinking provides progress by leaps.
To support the weight of the two peninsulas he was rebuilding, Lee looked at prefabricated floor joists. The webbing is made from particle board, and there is a wide flange on both sides of the web. Voila, instant I-girder. The girders were supported with simple legs, no diagonal bracing was required, and the flanges provided a place to attach joists to locate the risers.
For roadbed, Lee used 1" wide strips of 1/4" thick masonite (standing on edge) attached with yellow resin-based hot glue. To "rough-in" the roadbed contour, Lee ran a central spline of one strip around the risers. Two drywall screws at each riser located the central spline and allowed adjustment in contour. The eight foot long strips of masonite were bonded with an eight-inch overlap at each joint; the bond cured in under ten seconds, allowing work to proceed at a rapid rate. Once the overall track contour was acceptable, Lee and a couple of helpers went back and laminated more strips of masonite to the central spline. Working in this manner, and with the quick-curing qualities of the resin-based yellow hot glue, each eight foot strip was laid down in approximately 30 seconds. The cured spline is seven layers thick and exceptionally strong. Turnouts and other track features are handled by laminating a diverging path from the central spline. Large yard or other flat areas are Celotex vapor board sheeting. Fewer layers of masonite could be used for N scale, and thinner masonite stock could be used to achieve tighter radii. Surface irregularities are eliminated with either a sander or a carpenter's plane. Lee bonds cork roadbed directly to the masonite spline for laying track; the exposed edges of the masonite hold spikes quite well, eliminating the need for adding a layer of Homasote to the roadbed.
Remember, Lee completely rebuilt one half of his large layout in less than a year using this method. That includes installing scenery using a method developed by his associate, Kelly Newton, but that the subject of someone else's chapter. As people discover the ease, speed, and accuracy of using these techniques, masonite-spline roadbed is going to become immensely popular.
Want To use Wood, But Still Save Weight?
Most model railroads are severely over built. I use the analogy that if a Boeing 747 were built to most benchwork standards, it could not even taxi across the tarmac let alone fly. Wood has greater strength in compression loading, that is the weight applied and the direction it is applied in, than an equal weight of steel. Most builders use over-sized pieces of material, wood, to gain strength. We could save on both material and weight by designing structure to the inherent strengths of our chosen material.
Railmodel Journal magazine has run several articles on lightweight construction techniques. The most interesting appeared in the March 1995 issue. Think of how a hollow-core door is constructed; two thin sheets of plywood given depth by the perimeter frame to which they are bonded. Barry Norman, the author of this article, builds on that concept. He uses 2 sheets of 1/8" plywood bonded to 1X2 ribs on 16" centers; these are then ripped into 1X3 hollow boards and used for constructing frame members. Strips of 1/8" plywood are bonded in place to provide torsional rigidity. He points out that care must be taken to ensure that screws are always driven into sidegrain at the ribs for maximum strength. The "load" is always vertical to the grain of the ribs and vertical to the pieces of plywood. Strength superior to conventional 1X2s or 1X4s is achieved with far fewer materials and far lower weight.
How Else Can We Build a Layout?
So far, all of the construction techniques have been fairly conventional. Want to use fewer materials? Want to use newer composite construction technologies? Well, a number of model railroaders have heard the experimenters siren call and have tried innovative ways of building their benchwork.
Is this really foam? Bill Darnaby is building a freelanced model railroad based on the ever-intriguing Nickel Plate Road. He has forsaken the heavy benchwork described in the preceding sections and has elected to use extruded foam board as the basis for his layout. Bill specifies that only pink or blue extruded foam be used; the white expanded foam is not at all suitable for construction.
Foam-board construction is the essence of simplicity. A 1X2 strip is secured to the wall on 16" centers. An L-girder constructed of 2 1X2s is secured at right angles to the wall strip; the web of this L-girder provides the support for the foam board. Foam board, cut to the appropriate width, is secured to the web of the L-girder with Latex Liquid Nails. Foam board is extremely easy to shape; it allows stacking to build terrain features.
The advantages of this technique are rapid construction, low use of materials, and flexible design. The disadvantages are that it is best suited to shelf layouts of widths no greater than 18", and the foam transmits some train noise. Widths could be extended through the use of angle brackets on the cantilevered supports, but the increase is limited.
If you are interested in learning more about this fascinating technique, Bill Darnaby has authored several articles. The March 1995 issue of Model Railroader contains an article on the latest in foam-board construction. The June 1994 and September 1996 issues of MR include articles on applying specific techniques in foam board construction. Model Railroad Planning-1995 includes an article on Bill's Maumee Route.
What, more foam? The basic idea of foam-board construction can be applied to open grid layouts. Because of the micro-bubble structure of the foam, its affords excellent rigidity over open spans. A simplified open grid framework with minimal joists could support large sheets of foam board. The construction techniques described in Bill Darnaby's articles could be used to complete the layout on the foam surface.
Jim Kelly's ABCs of Benchwork article describes attaching a simple frame to the walls of a room and bonding foam board to it for a simpler, if less sturdy, version of Bill Darnaby's benchwork.
Modular bookshelf components. Have you ever looked at those bolt-on bookshelf brackets and shelves and thought "there must be a way I could use those to build a layout". The components are relatively inexpensive, and relatively easy to install. Model Railroader magazine ran a fascinating two-part article in January and February of 1977 that described how you could use these components.
The author, Robert Lutz, used a custom-fabricated C-bracket attached the modular bookshelf hangars to form his layout. The spans between the brackets were created with conventional wood and masonite materials. This created a shadow-box effect, with a layout depth of 12"; wider modules could be created for specific scenes.
The appeal of this method is layout modules that can be removed for work or moving, plus the module "boxes" still provide book storage space above the layout. Use of modern composite techniques, such as foam boards, could update these bookshelf units. An N-scaler, Gil Braugh, is planning just such a layout; he is using an E-bracket (to give him two operating levels) patterned after Lutz's C-bracket permanently attached to his walls; instead of wood materials, he is using foam boards supported by the brackets for his benchwork. I am looking forward to seeing how his technique works outs as this is the only application of this intriguing design technique I have encountered.
Look, up in the air; it's...a train?. Quick, tell me about the space you have available for building your model railroad. How did you describe it? I'll bet you told me how wide and how long the space is. But how deep is the space? That's right, >how tall are the ceilings. In the December 1996 issue of Model Railroader, Lance Mindheim describes how he built his model of the Monon Route in a 10X12 room, and still was able to use the full amount of floor space to provide a guest room. How? He built his benchwork at a height of 70", allowing the room to be retained for its "normal" uses while it contained an operating model railroad. Cantilevered shelves eliminate the need for table legs. Right now, look at the upper reaches of the walls of the room you are in; unused space that could be used for a layout!
Oh, you're Waiting For Information On Building A 4X8
Virtually all books and articles aimed at "beginning" model railroaders suggest starting off with a small layout built on a 4X8 sheet of plywood. I have attempted to show that there are very many better options for building any layout, beginning or advanced, than using the conventional 4X8 sheet. Using a superior construction technique allows you to "grow" the railroad as your experience grows. Still, a table-top layout has appeal if storage or moving is a problem.
Model Railroader magazine has done an admirable job in the last few years in promoting interesting and flexible alternatives to the 4X8 sheet of plywood. Every December, the magazine runs a project railroad designed to acquaint new modelers with layout building. Kalmbach's book, HO Railroad From Start to Finish, shows how to use foam-core art board to create a very lightweight table-top layout. The Alkali Central, project railroad from December 1995, shows how to build a table-top railroad that folds to save space when not in use. The November 1991 issue shows a table-top layout that folds into a custom-constructed cabinet when not in use. If a 4X8 plywood sheet still seems the best answer for starting your layout, be sure to add a 1X2 frame for support and rigidity. The main disadvantage to a 4X8 sheet? You have to start benchwork all over when you want your railroad to grow and become something more.
4X8 Is Too Large, Or You Want Something Easier To Construct
Small Railroads You Can Build shows how to build an N scale layout on a hollow-core door. The size is 36"X80". The door forms the base for an extruded-foam-and-plywood sandwich which is bonded to the door. Folding legs attached to the door provide easy storage. Using foam construction techniques detailed elsewhere in the book, you could eliminate the top plywood layer, building directly on the foam sheet which is bonded to the door. This should result in extremely light weight and extremely rapid construction. The 1996 project railroad from Model Railroader is an N scale layout built on a hollow-core door using foam, and will take you step-by-step through the entire process.
Other Materials No One Has Seemed To Try Yet
There are numerous other materials just waiting for an enterprising layout builder to employ. Structural corrugated cardboard is exceptionally strong in compression and extremely light. Fiberglass layups, especially with foam cores, are light in weight, impervious to virtually all deterioration, and very strong. Graphite fiber composite? You need an autoclave to cure it, and complex shapes are difficult to fabricate, but weight is unbelievably low. Joel Bragdon had a series of articles in Railroad Model Craftsman entitled Geodesic Foam Scenery; could his bubble-pack and polyurethane foam scenery sheets be used to construct a monocoque (i.e. self-supporting) layout bench? All of these materials, and many others, offer intriguing advantages for benchwork construction. The roadblocks to their use are waiting to be overcome. Maybe you have some favorite material or technique that no one else has thought of using. Share your ideas!
Conclusion - So Now What Do You Do
This chapter has provided a brief look at several proven, and some only slightly proven, benchwork techniques. The benchwork you construct for your model railroad can be useable for future development. Its future need not be consignment to the scrap pile. Your model railroad benchwork can live on and provide the foundation for much personal enjoyment. It is better to spend your time building your railroad rather than your benchwork. Be creative, be imaginative, be innovative. Engage in unconventional thinking! Most of all, share your experiments with others so that we all can learn new ways of solving problems.
If you have specific questions about different techniques, you can reach me at my email below. I will be happy to provide you whatever assistance I can.
About this content:
Original author: Bruce A. Conklin. Last revised in 1996.
This LDSIG article is ©1996 by Bruce A. Conklin