Model Spot – Detailing a Bachmann Class 24
Taking the Bachmann headcode box-fitted Class 24, Dave Roome describes a few simple upgrades and alterations for the OO gauge model to create an example at the end of its career. Simon Bendall provides the additional prototype notes.
Simon Bendall explains how to add detail to a Bachman Class 24.
Released just over a year ago, Bachmann’s version of the headcode box-fitted Class 24 marked the introduction of a new tooling suite for the BR/Sulzer Type 2 family that should ultimately bring the release of most variants in 4mm scale. The model’s appearance also served as an upgrade on the original disc headcode version, an older model that was somewhat lacking in both specification and fidelity in some areas.
Although correctly marketed and frequently referred to as a Class 24/1, this designation does not just cover the headcode box-equipped examples. As with the Class 25s, the physical appearance of the locos has no bearing on the subclass but is related instead to internal matters. In fact, all Class 24s from D5050 to D5150 (24050-150) were Class 24/1s. It just so happens that from D5114 onwards the cab design was changed to replace the disc headcode arrangement with a headcode box instead.
The main difference between the two sub-classes was an almost six-ton reduction in weight, something that was desirable as the initial locos had been delivered over their specified tonnage, thereby affecting their route availability. This diet was partly achieved by fitting a smaller fuel tank to D5050-D5120, while further weight shedding was achieved on D5121-D5150 by utilising both the reduced sized fuel tank and a smaller boiler water tank. As both of these tanks were mounted externally around the battery boxes, the class displayed three distinct appearances when built.
Of the headcode box Class 24s, D5114 to D5132 were built for use in Scotland and included tablet catcher equipment and the associated cabside recesses. The remainder of the batch were initially based on the London Midland Region, apart from D5147-50 which were new to Gateshead in the winter of 1960/61. The Scottish locos would also become notable for receiving twin headlights from the late 1960s due to the large number of ungated level crossings to be found on the Highland routes.
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English head north
Notably, the four Gateshead-allocated locos headed north of the border in October 1971, D5147/48 going to Polmadie and D5149/50 to Eastfield. Firedamaged D5149 would be withdrawn 12 months later, leaving the other three to become 24147/48/50 in April 1974. With Bachmann’s model covering the English batch of D5133-D5150, this provides an easy and prototypical route to using it on Scottish-based layouts in the 1970s blue era without needing to add the headlights or tablet catcher recesses.
As my layout is based in Scotland, I took this precise route in order to create the last of the class (24150) in its final year, 1976. With the BR blue donor model of 24137 dis-assembled, the first job was to remove the cab front gangway doors as these had been plated up on 24150 by the mid-1970s; all of Bachmann’s initial releases still have them in place. I masked off the bodysides to protect the paintwork, along with the glazing, before cutting away most of the raised gangway door detail with a scalpel.
Next, two-part filler was used to fill the gaps around the doors and left to set thoroughly overnight. Using fine wet and dry paper, the filler was sanded flat until a smooth finished was attained and it was then given a light coat of grey primer. This will show up any imperfections so the filling and sanding should be repeated if necessary. It is worth noting that on the real thing some examples still showed their door seams after welding up, so the finish does not have to be perfect! Once I was happy with the look, a light coat of white primer was applied to the whole of both ends.
Adding the burble
I have DCC sound fitted in all of my locos and this Class 24 was to be no different, a LokSound v5 decoder with a sound file from Legomanbiffo doing the job. The loco comes with a speaker pre-fitted, but I opted to employ a Rail Exclusive 26x20x8mm speaker instead, which is fitted in the water tank. The factory speaker has to be removed first. It is sitting on top of the circuit board in a sound box that can be un-screwed and lifted out.
With the water tank carefully pried away from the underframe, I had to make modifications to accommodate the speaker. Essentially, both sides of the tank had to be cut away from the central section at the base of the angled sections, but retaining the recessed gauges. The picture shows where the cut should be made on one side and then repeated on the other.
The central section can be discarded, and the two now separate tank sides glued to each side of the speaker, checking everything is in the right position and clear of the bogie. This new assembly can then
be put in place on the underframe using good quality double-sided automotive tape, while at the same time feeding the speaker wires up to the circuit board. The reason for using tape is that it makes it easier to replace the speaker if necessary, and I also covered the underside of the speaker with a strip of insulation tape to protect it.
With the decoder programmed with the last three digits of the loco number, it can then be tested on a rolling road to make sure everything is as it should be. The volume levels of the sound chip can also be adjusted to suit.
Wheels and paint
As my layout is built to the finer P4 gauge that is, 18.83mm rather than the 16.5mm of OO the loco had to be re-wheeled with scale wheelsets, which came from Sutton’s Locomotive Workshops. Bachmann has slightly changed how the bogie frames fit and has now added four screws to the bottom of the frames to keep them in place. Once they and the frames are removed, the wheelsets can be lifted out and stripped down using a wheel puller and gear puller. This gives a set of bearings and gears to fit onto the new P4 wheelsets, but before they can be added the same stripping process has to done to the replacements as they come complete with gears and bearings to suit the SLW model of the disc headcode Class 24s. With the wheelsets assembled, I gave them a little bit of grime and, when dry, a coat of matt varnish on the sides to dull things down.
Returning to the body, it was time to reapply the warning yellow to the cab fronts.
I gave these a couple of light coats with an airbrush and left them to dry overnight before adding the warning flashes. Photos should be referred to for this as, in this case, they were in a different position at each end. I also reinstated the blue star multiple working symbols and then applied a light coat of matt varnish. With this done, the bodyside masking tape was removed and the etched works plates were put in place, although not all locos still retained these by the mid-1970s.
Weathering
Before reuniting the body and chassis, the cabside and cab door windows were masked off in preparation for weathering, as were the wheels, as well as possible as these had already been dirtied up. For the weathering, I mainly used enamel paints but also some oil paints, and always working from photos of the selected loco from the right period.
The grilles first received an oil wash of black and were then left to dry, after which the whole model was given a light coat of dark grey. The latter was then mostly washed off straight away, using a brush soaked in white spirit and remembering to always work in a downwards direction. This should create an appealing look, particularly on the cab fronts, where the dirt has been washed off but has collected along the bottom edges.
Next, the roof was airbrushed with shades of weathered black, building it up around raised areas. A one-inch paintbrush was then used to go over the roof from side to side to give the appearance of rain washing the grime away, which can be a very effective look. Using some BR blue with a very small amount of white mixed in, areas of the roof that would be prone to fading from the sun were dry brushed. This technique can be applied to the sides as well and to fade the warning panel yellow. Lastly, black was airbrushed over the exhaust port on the roof, along with the steam boiler outlet.
When I was happy with the look of the body, I could begin on the chassis with my own mix of paint. I applied a light coat over the chassis and lower bodysides and blended it in using the big brush, again working in downwards strokes to give the effect of rainwater. Another layer was then airbrushed on to ensure the whole area was not too uniform in appearance before I turned to highlighting certain details. Using oil paint, I added black washes around the axleboxes and the fuel tank filler and then a very light dry brushing of dark rust to the brake blocks.
It is important at every stage of the weathering process to step back and assess the overall look of the model as it is easy to go too far. When I was happy with the finish the whole loco was given a coat of matt varnish, for which I used an acyclic-based type. I then left it to dry for 24 hours. The last job was to remove the masking from all the windows, which were then given a very light wash of thinned grime. As this wash starts to dry, any excess can be removed with a cotton bud. While this loco is by no means a massive project, the effects give the model a realistic appearance that blends it into the overall look of the layout.
"Although correctly marketed and frequently referred to as a Class 24/1, this designation does not just cover
the headcode box-equipped examples."