The Baseboard of a model railway is arguably the most important part of the whole setup. This is because if you don't have a proper base for a layout the running and look of the layout can be seriously affected.
Size is of utmost priority on a portable layout but it is also important for static layouts too. For example, access to a restricted space such as a loft trapdoor or even through an average doorway will restrict the overall dimensions of an individual baseboard. The average size of each individual baseboard will depend upon the layout size and track plan. It is bad design to place outside frames or support battens directly under points if you are planning to install sub-surface point motors as the frames will be in the way. A similar design feature applies for turntables. Remember that on portable layouts, each baseboard must fit in your car/van, so it is useful to keep overall dimensions low as your method of transport may change more frequently than your layout!
The width of a baseboard must be such that it is comfortable to reach the furthest track to rectify derailments.
Consideration should also be given to the weight of each baseboard and this will depend upon the type of baseboard surface and battening used.
The height of a layout is important for both viewing and operational comfort. If the height is too high then many people will struggle to see the layout, while backache will result from operating a layout that is too low. Viewing by children can be assisted by a stout box/platform in front of the layout. Most exhibition layout are around 90cm high but this is only a guide figure. If you are seated while operating then the height of the seat will have a major bearing on the height of the layout. Viewing should be at least several inches above track level, but the height of scenery must also be taken into account.
A solid top baseboard is the preferred option for many modellers because of its simplicity. Quite simply a piece of flat board supported with some battening. The choice of material has varied over the years. Many years ago chipboard was recommended but this is very subject to damp unless suitably treated and is also difficult to hammer track pins into. Then Sundeala or high density fibreboard was recommended but this again softens with moisture and doesn't hold track pins firmly. The current choices appear to be medium density fibreboard (MDF) or exterior grade or marine plywood sheet. A minimum depth of 9mm seems to be ideal.
Regardless of what surface is chosen, it is recommended that the top and bottom are pained or varnished to protect the surface from damp.
Although the term is "Solid Top", only small layouts should be solid on top as access to the furthest part of the layout will be required for cleaning and fixing derailments. Larger layouts usually have a hole (operating well) in the centre for one or more operators.
The board may be fixed in position with countersunk head screws (and countersunk holes in the top) or with panel pins driven in at a slightly different angles to improve grip.
Open frame is similar in concept to the solid top construction except that only the trackbed is placed on the support battens. This allows gradients to be more easily constructed using vertical supports screwed to the horizontal battens. It also allows for variable height scenery to be constructed around the trackbed. Open frame is widely used for USA and Continental style layouts where mountainous scenery is required.
Softwood battening is used to prevent warping of the top surface of a baseboard. In general supports are required at a minimum of around 30cm (1 foot) to 45cm (18"). However, pre-planning is required to avoid planing battens under locations for point motors or turntables. Battening of around 5cm x 2.5cm (2" x 1") planed wood is adequate for most tops but reject any lengths with bowing or twisting when you are buying.
During construction, battens and vertical supports may be placed temporarily in position with clamps before final fixing with screws.
Battening is also used for the outside frame of the baseboard and should be build squarely to facilitate joining of baseboards.
Baseboards may be joined using appropriate coachbolts through pre-drilled holes with or without using metal(pattern-makers)dowels to aid location. Also holes may be pre-drilled to facilitate runs of wiring.
This type of construction is similar in principle to the aforementioned softwood battening. The main part of the structure is comprised of plywood beams constructed by sandwiching small wooden blocks between 6mm thick plywood strips. This should be an absolute minimum of 7cm in depth, but 10cm seems to be a good compromise. These length-wise beams are joined at ~60cm(2ft) intervals with single-thickness plywood stretchers which can either be recessed into the main beam or set inside with the joint reinforced with small 10mm*10mm blocks.
Plywood Box Section
This takes inspiration from the aircraft industry to create a deeper baseboard that is very light but still strong. Basically the base structure is a set of plywood boxes instead of a solid top and support battens. An outer frame is made from 9mm ply with a minimum of 7cm (3") deep, with various strengtheners made of similar sized plywood or softwood. Trackbed is then pinned/glued to the top of the frame as in open construction. Holes may be drilled in the supporting frame to facilitate cable runs.
This is a variation of open top construction. Pairs of battens are joined together at right angles to form an L shape cross section. These are laid horizontally to form the spine of the layout, then legs are screwed/bolted to them, and cross-members are added at right-angles to this at regular intervals (normally anywhere between 30cm-40cm).
The plywood trackbed can either be glued & screwed directly to the cross-members or can be supported above it using vertical support battens to support the plywood trackbed
Legs are made from more substantial wooden section or metal. Cross bracing of legs is usually necessary to prevent their collapse. When building a fixed layout, the opportunity can be taken to fill in the gaps between the legs with shelves or stock-drawers. For portable layouts it is important to try and weigh up the best compromise between weight, rigidity and easy of erecting.
Integral fold-in legs
Having integral fold-in legs on a portable layout as you can carry the baseboard in, release the legs and everything is set up immediately. It has the added advantage of there are no separate components to leave behind as everything is permanently attached.
Fixed removable legs
The advantage of these is that if the amount that the two 'legs' are spread out is varied the height of the layout can be adjusted easily. They also mean that you can set up the legs then 'plonk' the layout on top without having to try and multi-task and hold up the layout whilst fitting/folding out other leg types.
Kitchen Worktop Type Legs
These are more if you have a permanent home layout but tend to be very strong and look nicer than the other types of legs mentioned above.
Protecting your Board-work
Now that you have built your baseboards it is recommended that you seal the board and framework with paint or varnish to help prevent warping or twisting of the timber.
Now that you have built your baseboards you can begin to lay your track.