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Deck
7
Frame
Fixed layouts - “slab benchwork”
“Slab benchwork” is my term for benchwork that is built on a ready-made platform such as a flush door or a sheet of Styrofoam.
Flush doors are called “hollow core doors” in the American press. They are about 35 mm thick and come in various sizes. They are constructed from two sheets of very thin plywood, or sometimes hardboard. These are separated by a softwood frame that runs all the way round the edge. The softwood is typically 25 mm wide, or less, so anything screwed to the door needs to be really close to the edge as the thin plywood surface won’t hold screws. The interior of the door consists of a honeycomb of thin cardboard strips or a sheet of foam or fibreboard. The result is a strong, light and cheap unit. Best of all, from a model railroaders’ viewpoint, they are already built. In fact it is feasible to build a whole N-scale layout on a door.
A bit of work will still be needed though. First you must provide some sort of support. An easy way for a small layout might be to use cheap folding tables. Alternatively, for a shelf layout, the door could be mounted on shelf brackets. For a larger door-based layout, some sort of frame with appropriate-height legs would be needed. This will be addressed later.
As mentioned, the thin ply faces won’t hold screws. The surfaces are also so hard they don’t really take track pins. A way round this is to glue the track in place, which is a good approach anyway. An alternative is to bond some sort of sub-roadbed to the upper surface. A traditional material is Sundeala board but a popular recent approach is to use two-inch thick Styrofoam sheet glued to the door surface. This is the pink or blue variety used for insulation, not the white crumbly stuff used in packaging. An attraction of using the thick foam is that it can be cut away to model areas that are below track level. You will still need to glue the track as the foam won’t hold pins. You should use solvent-free glue so as not to attack the foam.
A final consideration is that the door construction and thickness make it difficult to mount switch machines to the underside. One option is to mount them on the upper surface and hide them in buildings etc. Another option would be to use manual turnout operation.
As an alternative to a door, some people have successfully used slabs of two-inch thick Styrofoam for shelf layouts, well-supported on wall brack- ets. Some have done away with wooden supports altogether but most have used some thin ply to protect the exposed edge of the foam and to carry electrical controls.
Although people have had success with this technique, some have re- ported their foam has become bowed after several years.
Fixed layouts - frame benchwork
Frame construction is the traditional way to make benchwork. 7 shows the basic idea. A rectangular framework carries a flat deck. The deck is referred to as “sub roadbed” in the USA and this term refers to any board carrying the track. The frame is traditionally made of 18 mm (3/4”) or thicker softwood. Its depth depends on the length of the board. For short units, say up to 4 ft long, a depth of 2” (50 mm) is strong enough. Deeper frames will be needed for longer ones. It may be better to use deeper frame members anyway, as they will provide protection for switch machines. For example Tortoise machines would need a depth of 4 inches. For building this type of benchwork, a “chop saw”, mentioned earlier is a really useful tool as it enables you to cut all the cross-members to exactly the same length and with square ends. If you don’t have one, somebody in your local NMRA group may be able to help, or perhaps you could get a local timber merchant to do this cutting for you. The cross members can be fixed using screws through the frame sides. These screws will go into the end-grain of the cross members. This will horrify woodworking purists but seems to work fine, particularly when a gap- filling adhesive of the “No Nails” variety is used for the joint.
Softwood is the traditional frame material. Most people use it because it is easily obtainable and works, but plywood is more stable. You may be able to arrange for a timber merchant to cut the ply into suitable strips. For a home layout, 18mm (3/4”) thick plywood is suitable.
Plywood is a good material for the deck too, although some people use MDF. Chipboard has been found to be prone to sagging but people have discovered that sealing the surfaces with PVA glue is a long-term solution to this. Nine millimetre plywood has been found to work well in the UK if the frame members are about 12 inches apart. People in the USA use much thicker deck material. Author Tony Koester says that the reason he uses 3/4” (18mm) plywood is that it is hard to find one-inch ply locally!
Although 9mm plywood takes screws well, it is hard to push fine pins or spikes into it. If you plan to use lots of pins, or to spike your own hand-laid track, you will need to add a layer of a softer material such as half-inch Sundeala board.
Gradients
One way to make gradients on a frame layout is to use the “cookie cutter” approach shown in 8. You will need an electric jig saw for this.
This approach is useful for the situation where a gradient starts from a flat area. The rising gradient is supported by gradually rising supports (called ”risers”) fixed to the cross-members. This technique provides smooth transitions from the flat board to the gradient. Whatever type of gradient construction you use, it is critical to avoid sudden changes in gradient. Unwanted uncoupling will be the result if you don’t. If required, areas of the deck can be lowered or removed for lakes, rivers etc..
8
“Risers” fixed to cross members support the raised road bed
Frame baseboards are ideal for flat areas such as yards but can also be used for more scenic areas. An example is where a track is carried on an embankment (called “a fill” in the USA). The plywood sub roadbed is cut to shape using a jig saw and supported on “risers” as shown in 9b. Raising the track like this allows for scenery to be below the track level, so it is good for embankments, bridges etc. In this case it is important that the plywood track base is well supported to avoid sagging. Every 12 inches is ideal. Because of its narrow width, the plywood sub roadbed should be at least 12 mm thick. This is one area where Tony Koester’s eighteen-millimetre plywood would pay off.