Yes, Paul. As you say, there was a whole raft of variations and modifications over quite a small batch of locos. You definitely need to pick a specific loco and date. I found the Wild Swan Profile books absolutely invaluable for mine.
These two locos are among the few for which I have any detailed, in-build photos. I came fairly late to digital photography, so all my earlier efforts were done before I could take reams of pictures. Indeed, the following shots of the BR Standard version were actually taken on 35 mm film by Barry Norman in connection with a proposed article for MRJ, which never came to fruition. I hope he won't mind me posting some of his work here. These files are re-sized scans of enprint sized prints he kindly sent me some years ago - hence the quality of the files.
Both locos follow my now standard arrangement of fully floating compensation, with twin beams on the centre and rear coupled axles and a single beam linking the front coupled axle and the centre of the bogie. The latter is arranged so that the frames can only slide and pivot under rubbing blacks and the weight is transferred direct to the external bogie compensating beams and wheel sets by means of a pin inside a hollow pivot tube; the pin bearing on a cross shaft connecting these outside beams. All a bit complicated, but it allows a realistic appearance and operation of the bogie whilst giving an almost exactly prototypical weight distribution and maximum stability of the loco on the suspension. My first efforts, with a fixed, driven rear axle, single beam on the front two and a bogie just along for the ride, tended to lift the inside rear wheel on curves - a bit like a kidies' tricycle toppling over when cornering too fast.
The arrangement of the bogie and front compensation is shown in this sketch and the photo shows the bogie assembly, less wheel sets. The hollow tube pivot is soldered into the bogie mounting frame spacer below the cylinders. Side control is by the hair-pin springs sticking out to the rear and there are light spring wires bearing on top of the axles to push the bogie frame up onto the side bearing blocks.
The bottom end of the pivot tube, with retaining wire can just be seen in this shot of the underside of the chassis. The wheel sets are held in by a keeper plate which carries the dummy springs, ash pan and hopper gear, sand pipes and support brackets, etc., and also the wire pick ups, which bear on the backs of the wheel rims, hidden behing the brake hangers and blocks.
Brakes clip onto mounting pins at the top and the rear assembly is fixed to the rear of the keeper.
One of the main purposes of the series of photos was to show how the outside drive gear was built up. The only parts of the DJH kit used were the cylinder castings, the centre axle drive gear boxes and the suspension links at the rear end of the main drive tubes. Everything else was scratch built from sheet, sections, tube and wire. I have to say that I'm rather proud of the universal joint representations. Till soldered up, they actually would rotate and drive the shafts! It was an interesting exercise to work out how to best split and build up the various parts of the gear. This is what I came up with.
Cylinder unit.
Main drive shafts and gear boxes. The bits of wire on top are parts of the exhaust steam to injector, steam heat and vacuum brake pipes located between the frames.
Reversing shafts and gear boxes (shown the opposite way round, for some reason).
The whole lot is held together with 14 BA screws to give the complete assembly.
Another highly visible and distinctive feature of these locos is the arrangement of the the lubricators and drive and the arrangement of pipes under the RHS of the cab. The lubricators are mounted on a massive cast bracket and part of the steam supply pipe to the exhaust steam injector passes through the bracket, just below the lubricators. I was very lucky to have access to the preserved fully size loco at Butterly for photos and measurements. Quite by chance, the engineering drawing for the lubrication system was clipped to a board near the loco, so I took a photo of the drawing and was later able to scale off for the bracket details. The injectors, bracket and piping, and the lubricator arrangements are permanently attached to the frames. Castings for the injectors and water feed valves are from Alan Gibson.
Also visible is the rather crude but effective adjustable length coupling bar to the tender and the intermediate rubbing blocks - there are matching blocks on the tender drag box. The coupling bar is adjusted so that the blocks almost touch to avoid visible play between loco and tender.
Here are the results. I also try to include as much piping as possible, to help create an impression of the real thing. Here we see two water hoses, vacuum pipe, steam heat pipe, tender steam brake pipe and coal space spray pipe.
Finally, a view of the fully assembled chassis, without the body. I've just noticed that, in this shot, the lubricator drive return crank has not been screwed into the correct position
Dave.