Twenty years ago my layout was built on three boards each constructed with a four by three foot sheet of chipboard on two by one softwood frames. They were noisy, even with cork under the track, were incredibly heavy and warped out of true so much that I could never get reliable running over the baseboard joints.

Returning to modelling twenty years on, I’m older and wiser, and realise that joinery is not one of my skills. So I began to look into the use of alternative baseboard materials. Although Cruikglen is not intended to be exhibited, I wanted the layout to be transportable so that it could be relocated without destroying it. It’s development will be a long term project, I’m planning that it takes me well into retirement (I thought that was about 10 years away, but our government seems to have other plans for me.) So I needed something robust, yet as light as possible.

Visiting a number of exhibitions I talked with modellers who were using various plastic foam board products. Some were using a traditional frame and securing the type of foam board with a plastic coating on each side, others had used loft insulation board with a four millimetre ply outer (a foam sandwich) whilst others insisted that plywood was the only worthwhile material to build baseboards with. Faced with conflicting enthusiasm for number of different construction methods an techniques the only thing to do was experiment.

My good friend Alan Powell is a cabinet maker by training and has joinery skills I can only dream of. He suggested another alternative, Wediboard. This is used in the construction of bathrooms, is very strong, very light and impervious to moisture. He quickly knocked a prototype board together, using Gripfill. The prototype board used the Wediboard as the surface and as uprights beneath the board. We jumped on it, walked on it and tried twisting it by each holding one end, but could not make it warp or twist. However it suffers from one problem, it does not take and hold screws easily. Much of track bed of Cruikglen is elevated from the baseboard but the main and branch stations are on the level (to stop rolling stock from rolling away!) and so we decided that Wediboard, robust as it is, was not something we could use as securing point motors would be a huge problem.

In the meantime I’d been playing with 10mm thick foam board. Again it was used to make a prototype, again was pretty strong (although it would warp when manually twisted by gripping each end) and very light. Again it suffered with the same problem as the Wediboard, the inability to take and hold screws. Onto plan C.

When I last did any loft insulation rolls of fibreglass were de rigeur but these day sheets of insulating foam sheet are used. There are dozens of brands and thicknesses available, but I experimented with Celtex TA400 - 25mm foam sheet. Removing the silver paper coating left a board which was strong and impervious to water, but which could be carved and sanded to shape. Given the 3D nature of Cruikglen the idea of being able to carve beneath datum was appealing. The foam sheet is not robust enough to be used without an outer coating, so I looked at a 4mm ply skin to cover it. This skin also provided an anchor for screws – it looked very promising. And so a test track was built, a simple oval with a small station with passing loop and a three track fiddle yard.

It is important that point motors fastened beneath the point they are to operate do not have any lateral movement. If there is even a little slack then the throwing of the point becomes a hit and miss affair leading to unreliable operation. To avoid this problem the point motors were screwed to 6mm ply and then the foam was routed out underneath to a depth of ten millimetres and the ply inserted into the routed hole, being secured with the afore-mentioned Gripfill. This worked extremely well, the electrical feeds for the point motors being terminated on PCB board glued to the ply. This looked promising.

Before the winter chills of 2010-2011 set in this test layout was set up in the garage. It withstood the range of temperatures encountered in the garage (I’ve yet to install heating) and held up very well. But, (there had to be a but!) It proved to be incredibly noisy. Even with cork over the foam surface each rotation of the motors in locomotives was magnified. Even smooth running wagons and coaches made a loud rumble as they ran around the test track. It turns out that the air cavities in the foam which help provide the high degree of insulation, act as miniature sound boxes amplifying every vibration of the surface.

Alan had been conducting his own researching, exhibitors attending the Hampshire/Surrey/Berkshire area at the end of last year must have wondered at the guy who spent his time with an ear on the baseboard, and crawled around under baseboards to check out their construction. He dully pronounced ply built baseboards as the answer, with cork or foam underlay providing the track bed and sound deadening. Having experimented with many new fangled approaches we’d arrived back at the tried and trusted method of baseboard construction.

Cruikglen will need 12 baseboards, many of them open plan to allow below the line scenery. However we decided to build a flat top baseboard to begin with, as the board I wanted to tackle first contains the MPD and has a large flat area with all the other track higher than the MPD. I’ll publish a track plan for that board next time. In the meantime I’ve included the plan which was drawn using Google Sketchup and a picture of how the real thing turned out. Without boring you with a blow by blow account of the construction,it is worth mentioning that 6mm and 9mm birch ply were purchased from a local timber merchant, who cut two sheets up to minimise the wastage and provide all of the separate lengths as determined by the drawings. For £96 I have enough pieces to build three baseboards from high quality birch ply, which at £32 per board compares favourably with commercial offerings.

Sketchup drawings of closed top baseboard construction.

The underside. This board has many points and so this rectangular strengthening lattice is dictated. On boards without such an issue I’ll use diagonal straighteners as they provide better resistance to warping.

Underside of the first board (actually board #4). Note that the holes are round rather than slotted (much easier to drill) and missing quarter dowel in some corners (I need to buy more). The white paint is actually a water proof sealant, the board was sealed all over before any scenic work began. The hole in the baseboard surface is to provide access to a point motor which is attached to track which rises above the baseboard.