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3-D printing a model


GTR car the windows were double, not single. This seems a major structural difference, but all the other dimensions match. It is possible that the car was modified by the GTR or that the roster was incorrect.


Detective work like this is one of the fun aspects of prototype modeling. It’s also one of the traps. We can go on sleuthing forever and never get any- thing built. Sooner or later you have to stop researching and accept that it’s okay if someone shows up with the orig- inal construction drawings shortly af- ter the paint dries.


Body


From a modeling perspective, the key puzzle is the roof, more specifically the ends. They are all compound curves, and there is not a straight line in sight. I saw a lot of sanding in my future, es- pecially if I ever wanted to model the CA’s mainline trains. Then, late in 2008, I was researching a clinic on us- ing computers in modeling and learned that 3-D printing had leapt out of Star Trek and into a world where people like me could access it.


The term “3-D printing” refers broad- ly to a range of technologies that enable things that exist only on a computer screen to exist for real. Basically, they all come down to slicing the object into very thin layers and then “printing” those layers one atop the other. After more than two decades in gestation, the technology is moving quickly. Today you can output objects in a mind-bog- gling array of materials, including met- als, ceramics, glass and, of course, plas- tic. Full color printing is available, and there is even a company experimenting with printing buildings, real buildings! This technology is going to change


our world in profound ways. From our hobby’s perspective, it’s a perfect fit. Today you can easily model one of the major roads in one of the common eras, but step off the reservation a little way and you soon find yourself scratch- building or scratching your head. We enjoy a remarkable range and specifici- ty of models today, but 3-D printing en- ables us to embrace every piece of equipment that rolled at any time. The limiting factor is information. Once I decided to experiment with 3- D printing I found myself on a slippery slope. Having created a 3-D computer model of one end, it was a trivial mat- ter to copy and paste it to make a sec- ond one so I didn’t have to cast the ends in resin. With two ends, it was easy to put them the right distance apart and extrude the whole roof between them. Then it was worth spending some time thinking about how to do the letter- boards, which need to fit precisely into 54


Modeling the car started in a computer (top), where a three-dimensional “model” was ren- dered in Google SketchUp® The body as it was returned from the printer included the in- terior wall details. The photo of the primed end of the car, below, shows that both the sides and roof required sanding to reduce the signs/layers from this particular type of output process. The door was printed complete with the handle on the inside and out.


MARCH 2012


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