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Cleat Screws
Cross member
9a
Riser
Riser
Cleats
9b
Road bed
9a shows how one inch square softwood “cleats” can be used to enable all the screws fixing the sub road bed to be fitted from below. This allows the complete riser and cleat assembly to be moved if necessary without needing access to the top of the layout.
When fitting a length of track base like this, the whole length can be clamped to the cross members and adjusted for level (or gradient). Only when this is correct are the risers screwed to the cross members.
Fixed layouts, “L-Girder” benchwork
Although the frame layout design works well, it does have one or two drawbacks. As mentioned earlier, the cross members have to be cut very precisely. Also, they are always at right-angle to the side members. This can be a bit awkward when arranging the risers for an embankment that curves around a corner for example. In addition, any fascia will also be straight unless you make special provisions.
L-girder benchwork overcomes these limitations. The key elements are two longitudinal “L-girders”. Their construction is shown in 10b. Two
pieces of softwood (or plywood) have glue applied and are clamped together to form an “L” shape. This is one of those situations when you can’t have too many clamps. The girders are then nailed or screwed together. Most people use screws but Model Railroader project layouts have used nails from a nail gun. This ensures that the heads are below the top surface of the L and won’t interfere with any joists (see below) . With screws you need to ensure they are properly countersunk. Whatever method is used the real strength comes from the glue and the resulting girder is very strong and non-springy.
The material used to make the girders is typically 18mm or 25mm thick. The top of the L is 44mm to 70mm wide. The size of the vertical piece depends on the gap to be spanned. Using 50mm deep material for the vertical member, the girder can span around 8ft; with 100mm it is claimed that a 20 ft span is possible.
For long spans it is probably better to use softwood rather than a similar thickness of ply. This is because you want the best resistance to bending. Softwood should be better for this as all its grain runs longitudinally.
Choose your wood carefully; good timber merchants won’t mind you looking through all their stock and only choosing the best. It should be straight and as free from knots as possible. If there are knots, avoid having any on the vertical member’s lower edge.
The overall arrangement is shown in 10a. The L-girders are shown in red. They are fixed a suitable distance apart depending on the final width of the layout. Transverse elements, called joists, are mounted on top of these and are fixed by screws that pass through the horizontal part of the L-girder from below The joists are shown in blue. In the USA, the joists are typically 4” x 1” but 2” x 1” works fine for 2ft wide layouts.
Although not shown in the diagram, the sub roadbed would be supported on risers in a similar way to diagram 9b.
This arrangement is much more flexible than the traditional frame approach. First, the joists can be arranged at any angle and at any spacing, This makes supporting a curving road bed much more convenient. Also, the L-girders do not have to be parallel, so it is easy to make tapered baseboards.
Secondly the joists can be of any length, so they can overhang the outer edges of the joists (or not) as you require. By having overhanging joists of various lengths you can arrange a curved fascia along the front of the layout if this is appropriate. Finally, the joists don’t have to be cut so precisely as the cross members on a frame layout.
10a also shows two possible ways of arranging the spacing of the girders and fixing the legs. The nearer legs are fixed to a cross member that is like those on frame boards described earlier. The pair at the far end use one of the joists to space the girders and fix the legs. The legs would need some sort of diagonal bracing as explained later. This has been omitted from 10a for clarity.
roadbed cleat
fascia riser
optional shelf
11
joist
11 shows how the L girders, joist and risers are fixed. Note that all the screws are accessible from underneath. This means that the joists, cleats and risers can all be moved if plans change. For example, if a riser prevents the installation of a switch machine, the appropriate screws can be removed from under the layout and the complete joist/riser/cleat assembly moved aside and re-fixed.
It is possible to use an L-girder arrangement like this for flat layouts too. Just fix a sheet of plywood to the tops of the joists.
Finally, as shown in 11, you can easily fit fascias and shelves. Fixed layouts - supports
Narrow layouts, up to about 18” wide, can be mounted on commercial wall brackets as shown on the left of 12a. Home-made brackets can also be constructed as shown in 12a and larger ones can be made for wide baseboards as shown in 12b.
The plywood gussets make it unnecessary to cut the softwood parts super-accurately or to make joints.
Something to be aware of is the weight of the layout. What seems light can become pretty heavy once the track, wiring, scenery etc has been added. The increase can be surprising if a lot of plaster rock castings and
10b
L- girder is made from two pieces of soft- wood or ply glued and screwed together
10a