Large Radius Corner Build
Background
In 1906 the Darjeeling Himalayan Railway introduced its first generation of bogie carriages. Similar to some of the earlier 4 wheel carriages they had elegant large radius corners with curved framing.
The corners look complex to build but are not. With a bit of patience they are quite easy to form and need no special tools as the parts are already cut.
Note that this build guide is an abridged version of the written instructions focusing on key elements.
Step 1 Structure
The underlying stiff structure is a key part of the build. It is largely hidden when the model is complete and as can be see from the image it is of tabbed construction that easily slots together.
Once the glue has cured it is ready to form the curves.
Step 2 Preparation
In order to form the curves it needs to be wrapped around the structure. It can get a bit wet and the surface will need holding down on a solid board either with a stack of tins or with a tin and a clamp as shown in the next surface. Clothes pegs will also be required.
The first step is to draw a line down the centre of the surface adn structure which will be used to line them up when ready.
Step 3 Bending
In order to bend the surface it needs to be softened. It should be placed in a saucepan of water and brought up to near boiling for 5 to 10 minutes. Its best not to boil as it makes it float and then the top dries so it takes longer to soften. The kits contain scrapes of material so that they can be fished out and tested without risking the surface. Care being taken not to scold yourself.
Normally with steam bending speed is important as the wood must remain hot to work. But in this case the wood does not need to remain hot. Being so thin is cools very quickly and hence is easy to handle. Typically you have 30 mins to 60 mins work time if kept wet so it is best to let it cool then be slow and methodical.
Using lots of PVA on the surface of the structure and lining up the previously drawn lines carefully pull up the sides and peg in place with as many pegs as you can fit in. Clamp or hold down the middle so that it cannot bulge up. Leave until the glue has set.
Step 4 Framing Layer and Finishing
Once the surface has fully dries it will shrink slightly and tighten. The same procedure can then carried out again for the next framing layer. The final finishing requires a sharp craft knife down the edge of the structure layer to clear off any overhang. The other end can be completed in the same way and then the middle section of the carriage completed.
Challenge
The guards luggage composite offers the greatest challenge as cut outs slightly complicate the structure and alignments.
Note full printed instructions are included in every kit. Example instructions can be found on the How to / Resources page.