A 3D-printed freight car, Part 2

 The potential for 3D-printing of entire freight car bodies has been recognized for some time. But the latest one I have seen is remarkable in the amount of detail parts that can be printed on the car body or underframe. I showed those parts as they come from the printer, produced by Eric Boone, in the previous post (see it at: https://modelingthesp.blogspot.com/2022/04/one-piece-3d-printed-freight-cars.html ). 

When the car body is freed from its supports and base, the underfloor is revealed, containing four hexagonal cavities which accept 2-56 nuts, that will in turn accept the truck screws and coupler box screws.

And with both pieces removed, the underlying “forest” of supports from the printing process are revealed. These are fairly brittle, so care is necessary in cutting the parts free. But I found that this goes very quickly, mostly using a sprue cutter on the outer supports, then a utility knife on the remainder.

Eric recommended that as soon as the underframe part is freed from its base, that it be glued to the car body, in case it should have a tendency to warp. I did that, using canopy glue. As soon as that was set, I looked toward the parts I would be adding, brake staff and wheel, and sill steps. For these, I wanted to compare to the prototype, 2000 cars built in 1930, numbered PM 90350–92349.

My first stop was to look up these cars in the superb book by Arthur B. Million and John C. Paton, Pere Marquette Revenue Freight Cars (Hundman Publishing, 2001), which I reviewed in an earlier post (you can see that review at: https://modelingthesp.blogspot.com/2018/01/auto-industry-traffic-part-6.html ). 

Here I learned that the first 1500 cars of this 2000-car group were built by Pullman, with the last 500 coming from Pressed Steel Car Co. and having end doors. Of the Pullman cars, having side doors only, all but the first 300 cars were equipped with auto loading racks, AAR Class XAR. Obviously our model, not having end doors, models one of the Pullman-built cars. Below is a photo of one such Pullman car (C&O Historical Society).

Note on this car that the sill steps correspond to A-Line Style B. Eric Boone’s kit directions suggest Style C, which would indeed be correct for the Pressed Steel Car products but not for the Pullman cars. 

Starting in 1948, Chesapeake & Ohio (having taken over Pere Marquette) began to renumber the cars we are discussing, renumbering most into six-digit numbers groups within the 254000–256000 series. By 1953, when I model, the Official Railway Equipment Register shows that about 500 of the Pullman-built cars in the series we are modeling remained with PM reporting marks. Accordingly, I will so letter my model. For those wanting to letter for C&O, there is a photo of one of these cars in C&O lettering on page 146 in the Million & Paton book. 

One last prototype detail: by 1953 all but a handful of the surviving PM cars of this kind no longer had auto racks, were then Class XM, and were assigned to auto parts service. Therefore, they did not have the white door stripes indicating auto racks, and would have actually looked much like the builder photo above (except the word “furniture” had been dropped).

Last task before painting was to install a brake wheel and staff. I used 0.019-inch brass wire and a wheel from the parts stash (maker not known), and attached them with canopy glue. I will move on to painting and lettering in a future post.

Tony Thompson