Page 6 - March April 2000

HO Module Benchwork Peter Everitt (Photos by the author)
I have been interested in model railways for as long as I can remember, starting with Hornby ‘O’ gauge at age 4.
I went through the other usual stages for the 50’s and 60’s period; ‘OO’ gauge general, GWR branch line, obscure South Wales branch line, even flirted with EM and EEM (later P4). Anyway I managed to pass successfully through all these and got into real (i.e. North American) model railroading around 1970. By this time I had experience of layouts on the carpet, on a board on the carpet and in a garage; so I knew quite a lot about the less ideal places to build a layout and the problems they cause. I had started to put some of these lessons into practice when I got diverted by other ‘interests’, cars, houses, wives (sorry wife, one is enough), children, live steam, model boats etc. in approximately that order.
I didn’t get back seriously into small scale model railroading until 1990, just before my second job and house move. It was this move which brought me into contact with the Cyder Belt and with the Modular Railroading meetings which they operated. This appealed to me because it allowed members to run prototypical length trains without needing 10 years dedicated effort, a mansion and a small fortune to build the layout. As an aside I have an ambition for an exhibition layout which can reliably run scale half mile long trains, but that is another story. Anyway going back to the original plot I set about designing and building some modules; easily said but not so easy to do, particularly since the existing modules were built to several different methods and some of them were showing signs of sagging track with the consequence that long cars came uncoupled over the joins between boards.
Since there appeared no obvious ideal example to copy I went back to first principles, i.e. What are the basic requirements?
1. Rigidity
It should not distort under the weight of scenery or stock.
(A four unit all powered lash-up can weigh over 6 pounds)
2. Stability
It should hold its shape under all the conditions it will experience, in storage as well as operation.
(No sagging, especially of the track bed).
3. Ease of handling
• nothing should protrude outside the basic box
• edges need to be robust because they take most knocks and scrapes
• strong enough to survive the impact forces generated by its own weight
• as light as possible to minimise these impact forces
• easy to hold on to without causing damage
• legs attached to the boards to minimise the ‘loose parts’
So, what are the ‘golden rules’ to achieve the optimum result. The basic ‘golden rule’ is that there are no golden rules because there are always several ways to skin the cat; and this is well illustrated by the various recent articles on this subject in Roundhouse. However at the risk of provoking a response from all the real experts out there this is what I have done.
I believe the key to achieving most of these requirements is always trying to put the correct material where it can make the maximum contribution to the structure; and this will automatically result in a lightweight design. This means that the board will become a little more complex than we are used to but there is a lot to be gained by some small changes. The most important point in designing something for lightness is to remember that a light baseboard is the sum of a large number of light components, each saving is small itself but they all add up.
Some basic data to start with. First some weights and costs...
Table 1
Material
Hardboard (3mm)
4 mm ply
9 mm ply
12 mm chipboard
Sundeala
4 x 1 (96mm x 20mm) timber (or 2 x 2)
1 x 1 (18mm x 18mm) timber
Weight / sq. foot
0.7 lb.
0.5 lb.
1.0 lb.
1.6 lb.
1.0 lb.
0.65 lb. / ft
0.12 lb. / ft
Cost / sq. foot
£0.18
£1.00
£1.80
£0.40
£0.80
£0.75 / ft
£0.20 / ft
Taken overall I believe that a combination of plywood (for strength, stability and lightness) and small timber sections up to 18mm x 32mm (to keep the ply flat and for robust edges) gives the best compromise. The cost benefits of chipboard or hardboard are small compared with the total cost (see Table 3) and the use of these as structural materials can seriously damage the long term health of your module. Modules I have built have used reinforced 3mm or 4mm ply as the base for the third track and 6mm ply topped with Sundeala for the main lines; the aim was to reduce the noise of fast, heavy trains on the main.
In practice there appears no significant difference so I have reverted to 4mm ply reinforced by timber ribs (‘glazing bead’ 20mm x 8 mm). If anyone wishes to use Sundeala on top of the ply base they will need to lower the top of all the cross members by the appropriate amount. Also their boards will be heavier.
So back to the ‘golden rules’, what are they?
These costs are based on the typical DIY store prices for enough material for one pair of 4 ft. x 2 ft. modules. Prices reduce significantly for larger quantities, particularly if you purchase sheet material in 8ft.X4ft. sizes where the saving can be over 50%.
Now what is good and bad about each material...
Table 2
Material
Hardboard
Chipboard
Plywood
Timber
Sundeala
Advantages
cheap
strong, cheap
strong, good stability, light
strong, fairly stable, robust
holds track pins, absorbs sound
Disadvantages
tends to sag, heavy, ‘disintegrates’ when wet
tends to sag, very heavy, ‘disintegrates’ when wet
expensive, tends to splinter.
relatively heavy,
can be ‘knotty and warped’
very weak, heavy, sags
6 ROUNDHOUSE