Monday, July 14, 2014

Sneak Preview: 3d Printed Flat Car

Here's a preview for a future article: a 3d-printed Southern Pacific CS-35 flat car, circa 1903. I printed this on the Form One resin printer. The deck of flat car is individual pieces of stripwood, stained with india ink.

My obvious mistakes:
  • wrong number of stake pockets (should be 8 per side, not 9).
  • set of 12 rivets over trucks should be 6.
  • Deck is too narrow - the wood should stick out a few inches beyond the frame.
  • The CS-35 was made of fabricated steel components, and should have a hard edge on the bottom edges of the side. The curves are appropriate for the CS-35A, which used pressed steel components.
  • The car never really existed, it seems.

That last point was the killer. Tony Thompson's Freight Cars book shows two sets of plans for the CS-35 and CS-35A; only after I built it did I notice that niggling detail that there was no other mention of the CS-35 in the book. The 36' CS-35 was never built; instead, the SP went with the similar 40' CS-35A. Making a design for the CS-35A involved selecting each end of the car in SketchUp, and dragging it out to the proper length.

It's also been a pain to figure out how to print these reliably - to fit on the build platform, each is printed while leaning 20 degrees to the side. But I've now got castings for both the 36 and 40 foot cars. Once I've added a bit more detail on the underside, I can print enough freight cars to keep the Santa Clara Valley Mill and Lumber mill on San Carlos Street busy.

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