4mm ZCA ‘Seahorse'
Kit Corner describes the building of deceptively simplelooking ZCA ballast and spoil wagons in 4mm scale from the Cambrian Models kit.
It remains the view at Rail Express Modelling that kit building is one of the more important ways of introducing both diversity and a personalised feel to a layout fleet. Cambrian Models remains an important producer of plastic kits for modern air-braked wagons. Challenging to build and finish at times, the bulk of them remain valid today, including the ZCA ‘Seahorse’ kit.
MODELLERS keen to create realistic collections of modern wagons throughout the 1980s and early 1990s relied heavily on the ‘OO’ gauge kits by Cambrian Models, primarily for engineers wagons, although many revenue wagons were offered in the range too.
Affection for the range is high among modellers who experienced that era when hi-fidelity models of modern rollingstock we see today simply did not exist. Apart from building such classics as the fourwheel POA scrap wagons and the ballast hopper wagons, the kits were valued for the many additional parts found in each kit which were carefully stored away for wagon building and conversion projects once a wagon was completed.
This article looks at the relatively simple ZCA ‘Seahorse’ wagon kit (C16), which was a conversion from revenue air-braked OCA general merchandise open wagons. The kit may be assembled as it comes or is enhanced with detailing parts to make it stand out. It is, despite the simplicity of the full-size wagons, relatively awkward to work on, but builds up into a fair replica of the prototype wagons.
The Seahorse wagon
Conversions from OCA to ZCA
‘Seahorse’ took place in 1988/9 to produce a small fleet of low-sided ballast wagons with tall ends, which are documented as being intended to carry fresh ballast from quarries to yards to replenish part-filled ballast hopper wagons.
As conversions of various airbraked wagons for infrastructure duties continued into the 1990s under the umbrella TOPS code of ZCA, the small batch of 30 ‘Seahorse’ became mixed in with similar-looking ‘Sea Urchin’, which were used on the same ballast and spoil duties.
The wagons retained their original OCA numbers but acquired the DC prefix. First painted in engineers yellow and grey livery, by the 2000s they became more rust than paint, other than a handful repaired and repainted in EWS maroon.
The underframe retained all of the same features of the OCA, the conversion being a simple rebodying project. Air brakes, disc brake callipers, and Bruninghaus parabolic suspension springs on heavy-duty axleguards, together with round Oleo buffers, completes the picture. By 2020, all
of the ‘Seahorse’ wagons were long withdrawn from service.
Cambrian Models kit
The ‘Seahorse’ kit is a spin-off from the original OCA kit produced by Cambrian Models in the 1980s, and utilises the same plastic fold-up axleguards and underframe tooling for solebars, floor and detailing. The body consists of ends incorporating the headstocks and separate sides. The edges of the side pieces are bevelled to match those in the wagon ends. As it happens, the fit is not that good and some remedial work is required to finish the body to end corners.
Adding to the kit
Part of the fun in building Cambrian Models kits today is adding extra details which have become available over the years. The folding axleguards can be replaced by MJT Components ‘rocking’ compensation axleguards (trimmed slightly), or one of the sprung versions from Bill Bedford Models (through Wizard Models) or Stenson Models (www.stensonmodels.co.uk).
Better underframe detailing parts are produced as cast details by S
Kits (no website), including air tanks, distributors, axle boxes and suspension springs.
Whatever you decide to do, some items are not supplied with the kit.
The 12mm diameter disc wheels, brake disc inserts, couplings, paint and transfers are required. Nonetheless, with the steadily increasing price of many off-the-shelf wagons, the total cost of finishing a couple of ZCAs is not excessive in comparison, and will result in welcome variety in the wagon fleet, there being no ready-to-run equivalent.
Kit preparation
Plastic kits always need some degree of preparation before assembly, and parts in some Cambrian Models need particular care to get them to fit neatly together. The ZCA ‘Seahorse’ requires attention to remove moulding flash from some components as well as mould lines that run the length of the bonding edge of the solebars and the top edge of the body sections.
Each part is snipped from the sprue with sharp cutters, the plastic being quite brittle. Moulding flash is pared away with a sharp scalpel and the mould lines rubbed away by rubbing the pieces gently over grade 600 wet and dry paper. During part preparation, parts are test fitted as a dry run ready for assembly.
Compensation axleguards
Compensation axleguards by MJT Components were used in this project and assembled before the kit was started. Designed to convert a solid kit underframe to threepoint compensation, they are easy to assemble, with solder used to strengthen the folds and secure
2mm diameter flanged rolling stock bearing in place. One was fitted to the axleguard base using the slot and tab rocking pivot, while the other was prepared to sit solidly on a piece of black styrene card.
During kit preparation, the moulded ridges used to seat the folding plastic axleguards supplied with the kit were shaved off and the surface smoothed down with wet and dry paper, ready to accept the etched axleguard units. The centre lines were carefully drawn in with fine black marker pen. None of the locating pips for the sole bars were removed.
Kit assembly
Having spent some time on preparation, the kit should go together smoothly using liquid solvent cement. Application of the cement is done sparingly to avoid melting or warping any of any parts.
Assembly is undertaken on a piece of glass, aided with an engineers square to ensure the model goes together without any twisting of the body or underframe parts.
The body was put together first, with the join at the bevelled ends of the body sides and ends carefully checked and aligned. Left for a few hours to completely harden, the body and floor assembly becomes a solid base for solebars and underframe fittings. New brass Oleo buffers are fitted too because their height from rail is an important measurement to work to.
The compensated axleguards are next after some dry runs to check the height of the wagon from the rail and the degree of packing needed to achieve the correct ride height. Unfortunately, the solebars supplied are a tad shallow and this may show when the axleguards are installed. There is little one can do to increase the depth of them.
Everything is checked to see that the model is running true and square on all four wheels, and the rocking axleguard only moves by a millimetre or so on either side. Any more and the wheel set may choose to ride over rails rather than along them when entering turnouts and curves.
Detailing
Having completed the running gear and tested it, the model arrives at the detailing stage. Some parts from the supplied sprues are used, including some of the airbrake equipment and brake levers. A new brake cylinder and distributor are fitted alongside some detailing with styrene rod and strip to represent the brake push rods and pivots.
Cast metal axle box and spring detail is added to the exterior faces of the brass axleguards, being fitted to them with a small gap between the springs on the rocking unit and the solebar to allow for the desired movement. Some of the moulded suspension link detail integral with the main hangers is removed to accommodate the castings.
An alternative is to separate the axle box from the spring, the latter being fitted to the solebar and the gap between axle box and spring allowing for the rocking movement. This is very much dependent on personal preferences, as is the choice of spring detail. Cambrian Models themselves offer a plastic sprue of various types of suspension details, including the correct springs for the ZCA (C40).
Final detailing includes a representation of the disc brake calliper brackets shaped from styrene section by Evergreen or Plastruct. They are tricky to research, being tucked away in the dark under the wagon, behind the spring hangers adjacent to the axleguards. The callipers themselves are not modelled so as not to interfere with the rocking axleguard unit. A final task is to add some ballast to the underframe and lead-free shot is useful, secured with PVA glue prior to painting.
Paint and finishing
Time took its toll on the ZCA wagons, like any other used in ballast and spoil duties, with the livery of engineers yellow and grey becoming faded, covered in stone dust and battered with constant loading and unloading, usually with mechanical grabs.
The yellow and grey colours meet on a line down the middle of the wagon sides, with black applied to the underframe, headstocks and buffers. Inside, the body will be rusted and stained from ballast loads, probably a light dusty stone colour over a dark brown rust base coat.
Markings are available in parts on a generic sheet produced by Modelmaster and were applied to patches of gloss varnish, which are soon eradicated when the model is given its final coat of varnish – usually one that provides an eggshell finish, the ideal base for weathering.
When using sprung axleguard assemblies, avoid painting them unless you have a very steady hand because they become easily clogged by overpainting. Briefly dip the etched parts in metal blackening solution suitable for brass to colour them before finishing assembly to the model.
They should be masked during the painting process to protect them from paint overspray or anything that might seal up the movement of the sprung axle box in its journal.
Looking back
Is it worth going to the trouble to build plastic kits today? Modellers evidently think so, judging by the continued popularly of Cambrian Models kits.
One will never achieve the same level of finishing of some of the recently released £30-£40 ready-torun wagons, but that is not the point. Not only are they an economical way of equipping a layout with rollingstock, especially stock not available commercially, it makes things a little more personal – not to mention having the satisfaction of having completed something for oneself.
Naturally, how far you go is down to budget and it is not absolutely necessary to fit all of the additional parts used in this project.
However, the compensation axleguards are particularly helpful. Making up the folding plastic axleguards supplied in the kit is not easy and should you have a slight twist in the wagon body, the compensation should take it up and keep all four wheels on the rails.