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Monday, April 11, 2022

One-piece 3D-printed freight cars

 Ever since modelers recognized the potential of 3D printing, whether in resin or other materials, the idea has circulated of making entire car bodies. And a number of commercial projects have ensued, including at least two that I have written about in this blog. One was Southern Pacific Class W-50-3 ballast cars, produced by Robert Bowdidge (described in this post: https://modelingthesp.blogspot.com/2015/10/the-new-dry-creek-sp-work-cars.html ), and the 46-foot GS gondolas, a D&RGW design, offered by Corey Bonsall (described as part of an account of a Collinsville meeting: https://modelingthesp.blogspot.com/2017/07/interesting-products-at-collinsville.html ). Both are open-top cars.

Recently my friend Joe Binish in Minnesota let me know about a one-piece Pere Marquette box car that Eric Boone has produced. I was immediately interested, and Joe sent me sample parts. Eric gave me permission to show the car parts and to mention that he may decide to offer these as kits. 

When I received the parts that Joe sent, I was immediately impressed, not to say amazed. I show below the underframe part, with all the “runners” needed to produce the desired piece, complete with brake gear and rigging. This is printed from the flat plate at bottom, upwards to the final product on top.

Even more impressive is the car body, with radial roof, Dreadnaught ends, correct 6-foot doors, free-standing ladders and rungs, even open grab irons. Again, this is printed upwards from the flat plate at bottom.

I was perhaps most impressed by the  running board, not only standing free of the roof but also prototypically thin, and with corner grab irons.

It perhaps goes without saying, that there is considerable process refinement needed to arrive at a design which can create all these free-standing parts. You can sense that in the photo above, with the “runners” to the ladders. This view of the car’s B end, with brake platform included, along with running board end supports and the side and end ladders, illustrates the point.

I will proceed with the model in a future post. But once the parts are removed from the runners, all that needs to be added to these two pieces are the brake wheel and staff, stirrup steps, and of course trucks and couplers. Eric has even made decals for the car, and I’ll show the prototype car in the next post.

Tony Thompson

7 comments:

  1. I have to admit first off that I have virtually no knowledge of the 3D printing process. While the car body and floor look pretty good, I'm overwhelmed by all those "runners" used in the process. Is this model a "concept" effort, or would those runners be necessary on all models? Seems like the effort required to trim all of that off would be greater than simply assembling a traditional car. And the risk of damage around the finer details would, I think, be high. Am I missing something?

    -Jack

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    1. Jack, as I will show in the following post, the supports are very easy to remove with a sprue cutter or side-cutter pliers. It goes very quickly.
      Tony Thompson

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  2. The runners (in 3D printing, these are called "supports") are absolutely necessary, and proper placement of supports is one of the required skills for successful 3D printing. They should be very easy to remove - we'll see what Tony says about that. As for whether or not it's easier to "assemble a traditional car", I'd say that misses the point. 3D printing, like making a resin kit, is best suited to obscure prototypes, custom cars, etc. A big difference in 3D printing vs making a traditional resin master, is that the former requires computer and engineering skills, but relatively little manual dexterity. The latter requires superior manual dexterity, but no computer knowledge.

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  3. Thanks, Jeff. I just fell back on my knowledge of the terminology of metal casting. The supports are in fact easy to remove.
    I agree with you, that this is a ideal way to produce obscure prototypes, not mainstream models.
    Tony Thompson

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  4. I'll add two more comments: a well-supported model has the majority of the supports touching areas that are not visible after assembly. For example, the underframe has the supports touching the part that will be on the inside of the car. These supports may be removed (almost) carelessly.
    The other, more trivial, point is that these are printed upside-down. The "base" is suspended from the build plate and the model hangs down from there. So the supports are actually in tension, not in compression when the model is printed.

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  5. Just saw this. Interesting and exciting! While the other van Sweringen cars had radial roofs, I believe the PM cars had Hutchins Dry Lading. Nonetheless, an interesting approach and outcome. I look forward to seeing the completed model!

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    1. You are right, Ted, certainly the 1500 cars from Pullman had the Hutchins (peaked) roof, and so does the model. I was misled by the car diagram in the Million and Paton book, which is drawn with a radial roof, which may have been applied to the end-door cars.
      Tony Thompson

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