Saturday, 27 September 2014
Rolls Royce Armoured Cars - Part 3
Mudguards, Running Boards and Disc Wheels
Construction now turns to the mudguards. The following description is for the 1914 Pattern vehicles as the 1920 Pattern had a different style of mudguard. These will be described in a later post. Strips of 12 mm x .30 thou plastic sheet was cut and wrapped around a suitable former which was just smaller in diameter than the required curve of the mudguard. This was then plunged into boiling hot water for about five minutes and then placed into iced water. This allows the plastic to more easily retain a curved shape. I should mention that the aforementioned strips were partly curved before securing to the former by drawing them between thumb and the shaft of a screwdriver.
The strips were then set aside to dry. A start was made on the wire supports for the mudguards. As I intended to use 1.0 mm brass rod, holes of the required diameter were drilled in the chassis frames at the points indicated on the plan. Lengths of 1.0 mm brass rod were then cut and the last 15 mm was flattened using a hammer and the anvil on a bench vise. (This allows a greater gluing surface to the mudguard than just leaving the brass in its round state.)
The rod was then bent into shape using various types of pliers to get a uniform result.
They were then inserted into the holes previously drilled and the front rods were secured with super glue after checking for square, height etc. The rear rods were left unglued at this stage. This allowed a final adjustment so that the flat on the rod came into good contact with the mudguard when they were attached.
The mudguards, after being cut to length and curved around a small diameter rod to achieve the final curvature, were attached with super glue to the wires. (Noting the rear rods were not glued until the adjustment had been made)
Front mudguards installed.
The running boards or more accurately, the running board supports, were tackled next.
On the prototype vehicles, the supports for the running boards are attached to the outer sides of the chassis frames. As the models will no doubt be picked up and moved around the war games table by the running boards, these need to be as strong as possible.
To achieve as much strength as possible, I used strips of K & S Engineering's 6 mm x .04 mm brass. These were cut into 3mm wide strips as I couldn't find any thinner than 6 mm at my FLHS!
The brass strips were formed in to "L" shapes and glued with super glue to the inside of the frames as shown in the picture above. The cap of a circle cutter was found to be the correct height for the supports when attaching them.
To reinforce the strips, pieces of .40 x .40 thou shaped like the real supports were glued to both the frame and the supports. The running boards themselves will be cut to fit once the bodywork is completed.
The disc wheels on the 1920 Pattern were constructed next.
When I purchased the Cartrix wire spoked hubs I thought I was also purchasing the correct size tyre for them. This was not the case! Correct outside diameter, wrong inside diameter. Fortunately they are very suitable to use for the disc wheels. The internal dimension is 16 mm, so taking some aluminium tubing of that diameter and some plastic sheet I made up a front and back hub masters. The disc wheels are dished and domed on either side. To achieve this result I used the dished end of a pinvise and the domed end of a screwdriver handle to heat form some plastic sheet into the convex/concave shape.
They were trimmed down to the correct internal diameter, packed out and glued into the aluminium tubing. A simple box mold was constructed from plastic sheet and the casting process began. This has been covered in previous posts such as the WW1 General Service Wagons
The two halves were glued together and axle holes were drilled and the discs detailed with lug nuts etc. The rear wheel hubs were glued to a 7 mm aluminium spacer to achieve the correct width for the dual tyres. It should also be noted that the front wheels have the convex side facing out whilst the rear one have the concave side facing out.
The 1920 Pattern Chassis just waiting to have the running board supports fitted.
In the next post I hope to make a start on the hull.