Re: An informal poll


Tom Madden
 

These are not "revenue neutral" choices - adding extra cast resin pieces to a kit increases the price. And forget about color variations. Having to carry an inventory of all the pigments and dyes is a costly nuisance by itself, and each color recipe requires re-validation every time you open a new container of resin. Test samples use up a lot of very expensive resin. The workhorse resins we all use have one clear component (the base) and one with a yellow hue (the hardener). They cure white with a yellow tint. The hardener darkens with age, so a casting made from month-old resin will be more strongly yellow than one made using new resin. The maximum allowable amount of colorant is 2.5%, so you can't just load up the mix with colorant and overwhelm the background yellow - you have to compensate for it by adjusting the color recipe. And test it. Black is a no-go because, like white, the castings are very difficult to inspect for defects. Any castings I do will be my standard neutral gray, which is a 1% mix.


The above is based on my 15 years of developing color recipes for my rapid prototyping employer. The count now stands at over 2300 color & resin combinations, and I generated about 3/4 of them.


My personal preference for freight car one piece bodies, both as a resin caster and as a modeler, is to have the roof be part of the body with the underframe separate. These are not injection molded parts made to very tight tolerances - they are cast resin parts with dimensional variations, and the longer the part, the greater the variation. Those variations make joints between the underframe and body much easier for the modeler to conceal than between the roof and body. As a modeler I'm more than happy to let the pattern maker deal with the sides/ends/roof joints. The heavyweight passenger car roofs I offer are more forgiving because they all overhang the sides and ends. I could be persuaded to make the roof separate on freight house cars if they were overhanging roofs. I did make a lot of cast resin replacement roofs for the P2K 50' double door auto car, but there at least one of the components (the body) was injection molded and dimensionally stable. When everything is resin, it complicates things.


Getting back to my first sentence, a cast body will cost the same whether the ends are complete or just blank panels to which separate ends are added by the modeler. Separate ends would want to be cast in closed molds or, at worst, standing up in an open mold. Casting them as flat parts in an open mold will add thickness (the flash), and the roof length (assuming the roof is a separate part) will have to be adjusted to compensate.


Nothing comes easy....


Tom Madden 

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