Member's Projects

Roger M. has been working on a LSWR 1888 gunpowder van. He shares his progress with us.

Building a 4mm scale LSWR 1888 gunpowder van


Planning

Having built a few models from Plastikard I wanted to use some 0.8mm birch ply to assess the differences, especially the paint finish. The gunpowder van was chosen because of intrigue and the near certainty that there will never be a commercial RTR model. 


Prototype [ref: LSWR Carriages Vol. 4, G R Weddell, and HMRS drawings as below.]

At first the London and South Western Railway ruled that no explosives were to be carried, but they eventually built special vans. With at least one maker on their patch, along with Plymouth and Portsmouth naval dockyards they had little real choice! The first batch were built in 1888 but how many is uncertain. A second batch of similar vans were built in 1900 and there is a full General Arrangement(GA) drawing but again we don’t know how many vans were built. Drawings are available from the Historical Model Railway Society(HMRS), in collaboration with the National Rail Museum, as their drawing number 0990(1888) and 0973(1900). No photos are known to exist and the 1888 drawing shows the body only.


The lack of a chassis drawing for the 1888 batch means some assumptions are needed to build a model and these can be made from drawings and photos of more common vehicles built around the same time. Differences from the 1900 van include:-
- a single long brake lever and cast iron block instead of a double block and V hanger,
- conventional instead of self contained buffers,
- simpler ironwork on the body and solebars.

The small size of both vans is also notable with the 1888 van side door being only 4’6” high!


Construction

It is quite difficult to build a box accurately, especially with thin ply as it is rarely flat, even using a glass surface plate and engineer’s squares, so don’t look too closely at the photos! 

The sides and ends were drawn so that their base was the same and the planks lined up so all could be scribed with a marking gauge in one go. The sides and 1.6mm thick ply floor were designed to fit between the ends as the PVA glued joints would be covered by the side framing. Two partitions were inserted to avoid the roof and sides sagging and to contain a ballast weight, a small piece of lead flashing; see photo below.


 

Solvent welding plastic to ply can be done but uses a lot of solvent so the ply was sanded with old 360 wet & dry paper and given a thin coat of water-based matt varnish. The  headstocks were marked out on 4 x 1.5mm strip, drilled for the buffers and coupling hook and cut to length. They were welded to the body using the glass and square as a guide. The corner posts could then be cut from 1.5 x 1mm strip, tried and welded in position as they go down the ends of the headstocks. They were left slightly long for welding and filed to the roof slope and flush with the headstock bottom surface when the joints hardened.


The next photo shows the top rails cut from 1mm square strip, fitted and welded between the top corners of the posts. It also shows the doors cut to size, more on those later, and the solebars with axleguard castings glued on.

 


The solebars were tried in 1.6mm plywood but were difficult to straighten so 1.5 x 4mm polystyrene strip was used. Axleguard castings are old ones from Fourmost drilled to accept waisted brass pinpoint bearings, fixed to the solebars with epoxy using a jig made of card to keep everything level and a Masokits etched wheelbase jig to ensure correct spacing. 


This short wheelbase van will not be sprung or compensated, however, wheel and axle alignment is critical to reliable running and is difficult with kits. Typical instructions say, “Glue second solebar in place with wheels and bearings in place and check squareness, free running and alignment”: easy. So with your three pairs of hands you do that and when the glue is set you discover chronic misalignment from the direction you couldn’t see! To avoid this problem the solebars were cut slightly long and solvent welded each to a 10mm wide piece of Plastikard with a reinforcing strip between the castings. This allows the solebars to be set up with bearings and wheels and checked on a spare bit of ply; see photo below. It also allows the depth of bearing holes to be checked as the solebars have to fit between the bottom frames of the body; these castings needed relief for the bearing flange, about 3.2mm(1/8”) diameter, as well as deeper holes for the bearing body, about 1.8mm diameter.



Yes, those “craftsman’s clamps” are clothes pegs. The wooden ones are ideal for carving to shape for specific holding duties, including when soldering. A dial gauge caliper was used to measure the width over solebars. The photo also shows guide lines under the floor for aligning axles and reinforcing strips for the headstocks welded each side of the coupling hook slots.


The body side frames were all 3” thick outside the planks, which were 1.5” thick, but the door frames were only 1.5” proud of their planks. To avoid weakening the sides by cutting holes for them, the doors were cut from 1mm ply but sanded down to about 0.7mm thick; this was easy to gauge as it was just one outer ply. The doors were then checked and glued in position hard up under the top rails and dead central between the corner posts. 

The bottom rails were a bit fiddly. They should be 1.5 x 1mm but with a fillet on top to shed water away from the planks. Plastic strip 2.5 x 1mm was used and filed to about 450 for the fillet with a recess under the door. This left about 0.8mm below the floor level and on the full size van this was bolted through a crib rail(other wagon builders called it a curb rail) to the solebar. This is what determines the  solebar spacing and hence the bearing hole depth. 


The rest of the body framing was cut from strip plastic and fitted, hopefully so you can’t see the joints! For the diagonals this was helped by drawing the panel to size on the cutting board to get the angles about right. 

The photo below shows how the door framing was fitted to leave a small gap all round; any variations are due to the door sagging! It looks a different colour to the body frames because it is only 0.25mm thick. End posts from 1.5mm square strip have also been fitted and their tops tapered. 


About 1888 most LSWR goods vehicles had timber solebars flitched with an iron plate about 3/16” thick. This took the strain of carriage bolts and tie rods without using separate washer plates. To represent the nuts and washers here a new technique (culled from RMweb) has been used. Rather than stick on tiny cubes of plastic as in the past, 0.55mm holes have been drilled and 2mm lengths of 0.5mm plastic rod welded in place. More on nuts below . . .



A problem with models of outside framed vans and wagons is that a lot of iron work was used to strengthen the corners, diagonals and hinges. All the ironwork was fixed with coach-bolts inserted from inside with nuts and washers outside.  I have tried representing this with aluminium foil impressed with a scriber, etched brass strip and plastic strip with the nuts made of tiny cubes of plastic, about 0.25mm square, all solvent welded on separately, but they drive you – nuts ! For the last wagon, of which I hope to make a few more, a master was made to vacuum form the strips so I could cut them out with nuts already formed, so this sanity saver will be used again, although a new master is required because the ironwork is different; ‘t was ever thus. 


To be continued . . .

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