Thursday, January 8, 2015

Modeling SP Class A-50-17: the modeling

I have previously posted some prototype background for this project, at: ; now I want to turn to the modeling project itself. An overview of the modeling is presented in my article in the new Southern Pacific Historical & Technical Society publication Trainline, but I have space here to give details which wouldn’t fit in the magazine.
     As I explained in the previous post, the major modeling challenge was to reproduce the SP’s pattern of side sheets on this class of automobile cars, which had four sheets to the left of the doors, six sheets to the right (written as “4-6”), while the closest HO scale model, the Branchline (now Atlas) automobile car, had a 5-8 pattern. Moreover, the SP cars had double rivet rows, the Branchline car single rows. The key is the availability of a recent decal set from Archer Transfers, set AR88108 (a photo of that set was shown in the “background” post). You can buy them direct from Archer Transfers at this URL: .
     My starting point was this kit, though the particular railroad shown was of no importance (I would of course repaint the completed model). If you could find an undecorated kit, that might be simpler.

     Here is the car body from the kit, and you can readily see (with the lighting used in this photo) the 5-8 pattern of side sheets. The strips of single rivets defining the sheet edges will need to be removed. Note also the gussets at the lower corners of the door opening. These were not on the SP cars, so these need to be removed also. You can click on the image to enlarge it.

     For shaving off rivet strips and comparable jobs, I always use a brand new blade in my X-acto knife, in this case a chisel blade. Here the single rivet rows are very evident.

I used the same tool and method to remove the door-corner gussets, doing my best to retain the adjoining rivet rows, and also to remove the portion of the gusset below the door track.

Once these shavings are complete, I sanded all areas that had been shaved with 600-grit abrasive paper to smooth out the surface. Usually I mess up in a few model areas and have to fill any gouges or other scars with modeling putty (I use Squadron Green). Here is the sanded and filled body. Here the 5-8 side sheet pattern of the original model is obvious.

     Once all the work to this point is satisfactory, I like to airbrush on a “witness coat” of light gray. This helps make obvious any remaining flaws, and a little more putty is usually needed to refine all areas and ensure a smooth car side at this point. And for this particular project, the light gray coat will be a big help when placing the Archer rivets, which are black. The gray also serves, of course, as primer.

As is visible, I did need to re-putty a couple of areas of the body. Note that I also sprayed the car ends, and end detail sprues, gray. In this kit, those parts were black for the DT&I prototype, but I want them to have the same color basis as the rest of the model.
     Now the car body is ready to proceed with rivet application, which I will take up in the next post.
Tony Thompson

1 comment:

  1. "Witness coat" - thank you for that. I knew there was a descriptive name for that technique of priming/painting to determine what still needed to be done.