Brass etch kits, or etching sets, provide a useful way to produce good quality models of non-mainstream or obscure prototypes which are not of interest to the larger commercial model manufacturers who need large production runs to cover the costs of specialised tools and dies. They fill a gap between commercial models and scratch built models which many modellers may not want to attempt. Some people regard brass etchings as ‘hard’ as they usually involve soldering which is anathema. Soldering is not really all that hard to do once you get started and gain some practice. Basically it is just like using a liquid glue (Super Glue) which runs between the pieces to be joined. The solder has to be melted to run by capillary action between the pieces and it sets when it cools off. As for any glue, the pieces have to be clean and in the case of soldering the final cleaning of the metal surfaces is done by the flux. The metal is first cleaned of dirt, oxides etc. using emery paper or filing. You could say the filing does ‘mechanical’ cleaning and the flux does ‘chemical’ cleaning. Oxides build up quickly on the hot soldering iron tip and need to be cleaned off regularly with a wire brush. A potential source of complications occurs when soldering together long pieces. Thermal expansion can cause warping or buckling. It is best to ‘tack’ the pieces together in a few places; make sure they have not become buckled; and make corrections as required before going any further. You may have to unsolder, let the part cool, clean off excess solder and try again.
There are various ‘suppliers’ of etching sets. They generally supply few detail parts such as those mentioned below. Most modellers prefer to supply their own. My own experience so far has mostly been with the Worsley Works coach etch sets and I can best comment on these. These come as sets of etched frets and are really intended for use by scratch builders, providing hard-to-make parts such as panelled coach sides, fine grillwork etc. Bogies, wheels, buffers, coach roofs etc. have to be arranged by the builder. Coach etching sets are generally provided with the walls, ends and floor but, typically no roof. The floor may have fold down under-trusses and battery boxes etc. It is intended that the coach floor be made removable, held by screws, so that interior details and glazing can be put in after it is painted. There are no instructions supplied with the sets and it is best to first study the various parts to visualise and decide on the procedures to follow and in what order. The various sections should not be cut free from the etch frets until they are required for building up. Care is needed when cutting them free to avoid unnecessarily bending and stretching. The edges of the sections should be tidied up with a fine file so that they can fit up properly and cleaned where they are going to be soldered.
The best way to build a coach ‘kit’ is to start with assembling the basic coach body ‘box’. The coach sides should first be curved if appropriate. The ends can be used as templates for this. The method of actually bending the sides is up to the discretion of the modeller. It can be done by bending around a suitable piece of pipe or such likes. Care is needed to avoid stretching or wrinkling the thin etchings as it is difficult to straighten them again. The edges of the coach sides will normally overlap the ends at the corners. To ensure that the corners can be put together square and also to make sure they are strong and rigid enough to withstand normal handling, it is a good idea to put stiffeners inside the corners. The stiffeners can be made from left over strip from the etch frets, bent into right angles. They are soldered inside the coach ends, flush with the edges. The coach sides can then be lined up against the stiffeners and first just soldered to these. After any adjustments to get a proper fit, the rest of the join can be soldered up. The soldering is done from inside the coach to prevent ‘runs’ from spoiling the outside. The coach body should be checked to be square before going further.
The coach body will typically be lacking in rigidity because of the soft flexible etchings and it will be necessary to add some reinforcing. It is a good idea to solder in stiffener strips along the top edges of the sides. These could be pieces of brass rod, or can provide a use for salvaged otherwise unwanted brass rail. However, the coach sides may still be found flexible and it may be necessary to provide extra transverse stiffeners between the sides. A compartment coach will have interior partitions and these will help to reinforce a coach body. Obviously it is necessary to avoid buckling when soldering on long stiffeners.
Making the roof for a coach is another story. Normally no material is supplied by Worsley Works for making the coach roof. It is very difficult to properly form a piece of sheet brass to the correct shape, particularly the more sharply curved edges without a special (i.e. expensive) bending jig. One could adapt a plastic roof from another coach, by (say) splitting it along the centre and widening it out or otherwise adapting to suit the etched coach body It is possible to buy commercial wood lengths milled to various profiles and one these may be suitable or could be adapted to suit the particular coach. Another way would be to make one’s own roof, either from solid plastic or built up from plastic sheet and strips or from balsa. The roof when attached to the coach helps to make the assembly more rigid.