The superstructure and main feed tank

The superstructure of the prototype was made in wood and usually to a customer specification. For the model version, 5mm plywood should be used. The base plate (801) is fabricated from four parts glued together: the main plate with the large cutout; the two lateral stripes, and the front middle piece as reinforcement. The base plate is fastened to the girders (101) with six M3 countersunk screws. The two lever brackets (137) are attached to the base plate using M2.5 countersunk screws and nuts. Two elongated holes or slots are necessary for the brake handles. 

Footboards (802) and (803) are attached to the base plate (801) on each side with two hinges (804). These footboards must be movable to get access to the suction hose resting in the hose brackets (105). Very small screws must be used to fix the hinges in position. Pre-drilling and a drop of glue in the fastener hole are recommended to secure a permanent fix. 

The seat box (805) including the coachman’s seat is best made from plywood. The panels may be pinned and glued together. For extra strength, dowels may be fitted to the joints. The seat box cover (806), also made from plywood, is held in position together with the handrail fittings (807). The handrail consist of various components, the handrail fittings (807), the cup nuts (808) both are made from brass and fitted together with the centre handrail (809), which is made from a Ø 4mm brass rod and threaded M3 on both ends.

A footboard (811) is attached to the front panel of the coachman’s seat. The two footboard brackets (810) may be cut from a 5 mm brass sheet with a fretsaw and clamped together for finishing the shape shown. A small file is recommended for rounding the edges. They are attached to the back plates by M3 studs, and sweated together with soft solder. The footboard itself can be made either from very thin plywood or from sheet metal sweated together. My personal choice would be wood because it is more authentic. 

The seat rail (812) is formed from 4 mm brass pipe bent to shape and flattened at the ends. The back supports (813) can be bent from flat metal strip, but if ‘half-round’ or ‘fish back’ strip can be obtained, it will look much better. The handrail is fastened with small brass rivets, which are stuck with a drop of glue into suitable holes on the coachman’s seat.

Underneath the superstructure the main feed tank is installed across the underside of chassis. The tank can be made easily from brass sheet, as indicated in the drawing, with one piece folded to form the four sides (816) and having a single lap joint (not shown) at one corner. Three or four rivets will hold them together prior to soldering. The four sides are bent outwards at the bottom edge and attached in the same way to the bottom plate (815). Two nipples (819) to fit standard M6 unions are fitted with nuts (820) to the bottom plate. One of them needs to be extended upwards to form a socket for the overflow pipe. A lid (817) can be bent from brass sheet as well and soldered in place to close the tank.

The toolbox and rear side tanks (821) are the same general shape. They can be made from a single sheet of brass. It is recommended you make a metal or hardwood former to fit the internal shape. A slight radius at the corners all around is, in fact, preferable. Very small rivets with 1 mm diameter are specified for the lap joints. In addition, soft soldering will make the joints watertight. At the upper edge small angles (823) are riveted in place where the tank lid will be fastened with M2 countersunk screws. 

The Tank lid (822) is made from 1 mm brass sheet. A brass pipe with 3 mm of external diameter and 1.5 mm inside diameter is silver soldered to the edge of the lid parts. Now they can be notched to fit each other with close joints and fitted with a permanent hinge pin. The complete lid may now be trimmed all round the edge, and secured to the top of the toolbox or the tank by M2 countersunk screws. As an option a commercially available hand feed pump can be installed inside the tank and operated using a removable handle when the lid is open. The toolbox or tank is simply attached with two tank support struts (814) to the chassis girders (101) and with some M3 screws to the grating (825).

The grating (825) is fabricated from brass sections silver soldered together. The 15 bars (826) should preferably turned down at each end to receive plugs, which should be a little longer than the frame section thickness. Excess at the ends can be rounded off to give the appearance of a rivet head. The middle bar has an extension at one end threaded M2 where the centre strut (827) is connected, and which is attached to the main steam pump.

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part eight part nine part ten

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