SP piggyback, Part 4: progress on the 3D models

In this series of posts about Southern Pacific’s early piggyback operation, I provided historical photo coverage, including the flat car conversions that SP made for the original service. That particular post is here: https://modelingthesp.blogspot.com/2024/10/sp-piggyback-part-3-piggyback-service.html .) Now I want to turn to modeling of these flat cars and their trailers.

Last fall, I posted about some superb HO scale models 3D-printed and given to me by Andrew J. Chier, models of Pacific Motor Trucking (PMT) piggyback trailers, and two of the Southern Pacific’s original piggyback flat cars. (PMT was an SP subsidiary.) I included in that post a photo of AJ’s own completed models. Since then, I’ve been slowly progressing with completing these models, and that’s the subject of the present post. (You can see that previous post at: https://modelingthesp.blogspot.com/2023/11/more-amazing-3-d-printing.html .).

My first step was to free the trailer bodies from their as-printed supports, clean them up with care (because small details are fragile), and then give them a coat of primer. I used Tamiya “Fine Surface Primer (White)” for this. Below are two of the trailers, as primed. The excellent and complete detailing of these models is even more evident with the light color of the primer.

I did the same white primer on the flat cars, and then painted them with the Tamiya “Fine Surface Primer (Oxide Red).” It’s a bit too red for SP freight car color, but when weathered, the difference won’t be very evident. As with the trailers, the remarkable thing about this 3D-printed model is the completeness, with all the trailer support and tie-down equipment in place.

The question can certainly  be raised about the photo above, whether any of the trailer equipment was a different color than the car body. I believe, after reviewing a great many photos, that the answer is “no.” 

The prototype image below will show what I mean. It shows the relatively new piggyback terminal at the site of Los Angeles Shops, with trailer unloading in progress. It’s part of an SP company photo, dated 1955, and the complete photo is in my Volume 3 of the series, Southern Pacific Freight Cars, on pages 284–285. I can see no indication that anything differs from body color.

Next I needed to add weight to the flat car. The design of AJ’s model cleverly allows for this, with a pocket in the underframe. I showed this in the previous post (link in uppermost paragraph of the present post). I cut some 3/8-inch lead sheet from McMaster-Carr to fit, and attached it with canopy glue. Since it will be invisible, I haven’t painted the lead. The remainder of the underframe, not shown here, is a part that fits right on top of this.

In addition to this sheet of lead, there is a 3D-printed frame part that goes over it, and that part has effectively “pockets” that permit adding additional, smaller pieces of lead sheet. Again, I fixed these in place with canopy glue. In this way, the weight can be raised to the vicinity of the NMRA standard for this car length.

From here, the flat car project is ready for the details to be added (grab irons, sill steps, brake staff and wheel) and also lettering. The trailers are primed and are ready for their red and orange paint. I’ll turn to all that in a future post.

Tony Thompson