Casting of components can be a way of reproducing hand made parts so that each is identical. Commercial operations can involve very large outlays and this explains why the manufacturer must be confident of sales large enough to allow reasonable pricing and to cover the costs of pattern making and die sinking in particular.
In the home workshop our time is our own and the processes used are not as expensive as in the commercial world. The process is more labour intensive and in some ways is an in-between process; not quite mass production and not quite scratch building each time! Casting at home is not always cheaper than individually producing the parts but it is usually quicker and it does ensure uniformity of appearance for items that appear often. A good article by Adrian Gunzburg appears in the Australian Model Railway Magazine for August 1987, Issue 145. Some of the information regarding materials, especially to do with resin casting, are now out of date but the processes are very clearly described.
Low melting point alloys such as printer’s type metal can be used in silicon rubber moulds to produce components such as axle box assemblies for four and six wheel rolling stock, bogie side frames and other detail parts. I have used the technique to produce architectural details such as finials as well as a host of detail parts for locomotives and rolling stock. Examples include air compressors, lamps, generators, buffer housings and brake cylinders. Over the past few years access to competent and obliging commercial investment casting operations has increased and some modelers who used to produce their own white metal components are now having them produced in brass, bronze or nickel silver by this process. It still involves the modeler in pattern making so the personal input to one’s model is maintained. The parts are more robust and can be soldered without risk of melting the component.
The cost of having investment castings produced is greater than making your own castings at home. Obtaining the metal is, however, not always straight forward these days.
All this being said, I will outline the process for white metal casting in the home workshop. It is straightforward and easy once you are set up with the materials. The major hurdle that most of my acquaintances seem to have had is taking the initial step!
Information about casting in metal is available here.Information on resin casting is available here.