Mastering Making Metal ModelsCast metal was a standard model material until the age of plastic. In today's resin age many accessories and cottage industry models are still cast metal. Metal is in some regards superior to resin and easier to work with. Come along and see!
My parts bins are full of cast metal parts and figures and detail bits. Many are brass; some pewter and "pot metal"; some are composites; some are evil lead. Metal parts are ubiquitous even today, especially for large scale ship model supplies like H&R. Model railroaders are just beginning to accept the resin revolution although many of us prefer metal. This feature demonstrates how to build a cast metal model. The subject is the Wiseman Model Services O Scale Ford Style Farm Tractor kit, which has been thoroughly reviewed on RailRoad Modeling.
CharacteristicsMany metal models are short-run or cottage industry creations. This means that the molds and tooling might have been created by fellow hobbyists, many of whom, in day jobs, are professionals in related industries.
Casting can range from crude to top notch. The first step to building a metal model is understanding the characteristics of the metal. It's important to understand that depending on the age of the kit, it might contain lead. Years ago many model manufacturers removed lead from their mix due to EPA and other health concerns around the globe. Wiseman Model Services and I&R Miniatures both told the author that they do not use lead in their metal.
Cast model metal can run the gamut from soft to brittle. It usually has some "play" so if you knock it against something it will bend, not break. If you do bend it, it is malleable enough to reshape. However like resin, it might snap if overstressed; unlike resin it will probably be bent, which can be tricky to reshape and meld back together.
Another characteristic of many cast components is the surface. The physics of casting common model metal can result in a rough surface. Not necessarily sandpaper rough but usually more textured than injection molded plastic and poured resin; not always rough, many parts are smooth. Priming the parts with good primer paint can alleviate all but the worst texture anyway. Otherwise I find working with metal to be little different than styrene and resin and in some ways easier.
Easier?Yes. Why? If you get sloppy with tube or liquid glue you can melt your styrene. It can damage resin if you try to pick off sloppy CA. Metal is more durable and impervious to most any cement.
Metal can also be filed and sanded. Gravity works and metal shavings fall away nicely -- no worry about resin or styrene dust floating into your respiratory system! While sanding / polishing metal will clog your abrasive sheet, it is easy to remove waste from a file.
Another benefit of metal is drilling. While you should always let the tool do the work, you can really bear down on metal parts. Too much pressure on resin and plastic and it will crack or warp.
Finally, connecting the parts. Much cast model metal is soft and does not accept soldering well. In the old days the only practical way to join metal parts was with contact cement, like Walther's Goo, or with an epoxy. Today we have a cornucopia of high quality Cyanoacrylates (CA, or "super glue"). These work equally well on metal as with plastics and resins. I use BSI (Bob Smith Industries) products; they have a dozen CAs formulated for various tasks and they have always served me well.
There is a downside to metal parts. Oxidation. Today older modelers (and younger modelers with older kits) are finding some metal is oxidizing. Not all metal models but some. Not rusting but in some cases the metal is breaking down into a brittle powdery state. Careful cleaning and sealing can preserve the metal for the future, although I am not sure if deteriorating model metal can be saved.