Dunrobin...More progress

Boiler backhead in place with modified fire hole door

I had help from Paul Jarman at Beamish museum who supplied some photos of Dunrobin which clarified most of the details of the cab interior. I'm still not sure about my positioning of the Dreadnought vacuum ejector, which you can see sitting on the right hand inner tank top, behind the reversing lever. The original ejector was removed in Canada when Westinghouse braking equipment was fitted; it languished on a shelf in a workshop there, where fortunately it remained until its repatriation along with the engine in 2011. Apart from the ejector, which is provisionally positioned at the moment, the inner tank tops are at this stage still bare of equipment, though I'm sure that evidence will emerge of detail which can be added to enliven this area. The cast brass backhead supplied in the kit has been modified so the firehole is now correct with horizontal sliding doors and operating lever at floor level.

Photos from Beamish and a GA drawing of the cab area from Sharp Stewart the builder, provided the details for the seating in the cab rear. There are duckboards for the passengers' feet and a padded seat, which are above the coal space, the coal door is central at floor level. On the rear wall of the cab, above the windows, can be seen a coat rail; between the windows there should be a set of framed autographs of distinguished passengers, details of which I have yet to clarify.

Cab rear with seating for four people with coal bunker below.

Dreadnought ejector sits on the tank top connected to the ejector pipe which can be seen through the window.

Some of the castings for the boiler backhead are taken from the 4mm scale version of the engine which were rather over scale. Other cab details including the reversing lever and brake standard were constructed by the author. On top of the backhead sits a handwheel, a detail which I hope to enlarge on as my understanding of the cab controls and gauges develops. The wooden floor is constructed from model ship planks and is in two parts, left and right, to allow for removal. The mechanism for operating the tablet catcher is fixed to the end of the left hand inner tank. Note the inner sliding cab windows which are single skinned and will eventually be glazed by simply affixing a sheet of glazing to the rear after painting; the handles for these windows will glue to the glazing.

Tank tops and ejector pipe are well seen in this view.

The original ejector pipe was removed in Canadian days so I have relied on photographs to restore it to its correct position. It kinks towards the boiler after leaving the smokebox and is supported from the boiler just after the bend.  After running along the boiler towards the cab, the evidence of a hole in the cab front plate suggests that the pipe crossed over the tank top towards the outside of the engine to enter the cab and connect with the Dreadnought vacuum ejector inside.
Narrow Planet provided the etched nameplates.
The tapered buffer housings, which have a square base, were modified from a set of Slaters' GWR buffers but are still a couple of scale inches longer than the prototype's miniscule 9 inches.

Brass castings for rear sandboxes and picnic hamper boxes are soldered to frames.

Roof in place emphasises the large space occupied by the cab.

Dunrobin...Progress.

Dunrobin superstructure, parts in nickle silver are replacements or additions by the author

The cab sides needed the top rail above the cab door thickening and the only way I could do this was to replace the whole side. I'm working on the new sides in the flat, adding the inner sliding windows which completely enclose the cab when closed. The separate assemblies of the engine, the boiler and smokebox, the tank and cab sides and the footplate and cab interior, will be assembled when the interior is as complete as I can make it. The stepped seating arrangement in the cab rear is based on photos taken at Beamish, after Dunrobin returned from Canada. I have a couple of pictures of part of the inner cab front plate and the top of the backhead, though I the suspect that some of the equipment in the pictures was added in Canada and is not relevant to a model of the engine in original condition.

Part of the frame will be removed behind the front bogie wheel to allow the bogie free movement

Cab interior showing inner sliding windows and right hand drive reverser.

The cab of Dunrobin is generously proportioned because of the seating at the back of the cab and I plan to fully detail the interior though I have not yet obtained all the information I need to complete the backhead and other details at the front of the cab. I have a useful side elevation drawing of the cab, which shows the reverser well and allowed me to model the lever and its ratchet frame. On the opposite side of the cab, the fireman's side, stands a handbrake stanchion for which I also have information enough to make one.

An important consideration in building Dunrobin was the manner in which the cab windows were to be glazed to look convincing not only from the outside but from inside too. My solution was to double-skin the cab sides to allow the glazing to slide between the outer and inner skins. The sliding inner windows are a single layer with glazing glued behind them with ZAP canopy glue, which dries clear. These windows slide in 1mm U section brass, soldered inside the cab sides.
I decided not to double-skin the cab front and rear plates due to the presence of those etched ventilation slots high up between the windows, these I could not reproduce on the cab inner with any accuracy, so single skin they remain and I think they are more convincing as they are.

The driver's door on the right hand side is modelled closed because the driver will be positioned there leaning on door and looking out of the cab. The left hand cab door will be in the open position to allow a good view of the cab interior detail, the inner sliding windows will also be open.

ABC Gears triple reduction gearbox with 1625 motor  

Power is supplied by an ABC Gears "PUG" gearbox, designed for small prototypes, the 1625 motor drives the fixed rear axle through a triple-reduction gearbox.  The mechanism sits upright in the firebox and fits inside the diminutive 3ft 9" diameter boiler very neatly. Wire pick-ups bear on the rear of the wheel rims on the left hand side and on the right are shorted by means of an 0.5 wire running in a spoke, which connects the brass central hub to the wheel rim.