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Accessible 3-D printing for model railroaders

Learn about 3-D printing software and services for making custom model trains and other model railroading applications
Sketchup
Free software available online, such as Sketchup, can be used to design models that are produced by 3-D printing services like Shapeways. Alex Marchand followed this path to model a CSX class U-13 phosphate hopper in N scale.
Softwareproviders
When I was in high school in the late ’90s, I saw a TV show that ran a segment on the emerging technology of 3-D printing. Immediately, I thought about how useful those machines would someday be for model railroading.

I kept an eye open for the day when 3-D printing, or rapid prototyping, would finally become good enough, cheap enough, and user-friendly enough to use for my own model railroading. Then, in 2011, I learned about a service offered by a relatively new company at the time called Shapeways.Shapeways is a 3-D printing company that allows people to upload and buy their own 3-D printed designs.

Shapeways also allows individuals to open stores to let their designs be printed by others for a designer-selected royalty.

There are other 3-D printing companies out there, but I’ve used Shapeways, so I’m going to focus on my experiences using its services.

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Fig. 1 Cleaned up after printing. These models were printed in a material called Frosted Ultra Detail by Shapeways. The prints are covered in a waxy material Alex removes with Bestine, which turns the models from translucent to white.
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Fig. 2 Ready for the layout. Alex models phosphate mining activity in the Bone Valley of Central Florida. He had these specialty hoppers and this caboose printed to his design, then he painted, decaled, and weathered the models.
3Dprintingcompanies
Design

If you browse Shapeways’ website, www.shapeways.com, you’ll find many model railroad products available for sale. But if you want something not yet available, you’ll have to either design it yourself or hire someone to do it for you.

I will say that designing a 3-D model requires ample computer confidence, and the investment of a lot of time for learning. Not only do you have to learn how to use 3-D modeling software, but you also have to learn the design rules to make a design printable. Inevitably, 3-D design software will become more user friendly.

There are a number of 3-D design programs available for free online, such as Blender and Sketchup Make. Make is the free version of Sketchup. There’s also a version called Sketchup Pro, but it costs a few hundred dollars. I found Sketchup to be the easiest to learn. The main downside to Sketchup is that it isn’t good for designing organic shapes. But since most of the things model railroaders want to design aren’t organic shapes, Sketchup is fine. There are numerous tutorials on YouTube to get started with Sketchup.

Sketchup has a few finicky qualities that require workarounds, though. For one, you’ll want to work 10 times larger than the actual size of the model you are making. Sketchup doesn’t handle small dimensions well. If you work in millimeters, working 10 times larger is relatively simple. Also, for a design to be printable, it has to be what is called “watertight.” In other words, the model can’t have holes in it that make the printer unable to differentiate between what needs to be printed and what doesn’t.

Accutrans 3D software, which is free to try and inexpensive to own, solves both problems for PC users, but isn’t available for Mac. Before you use it, you’ll want to install a free plugin in Sketchup called “SKP to DXF or STL.” That allows you to save your model from Sketchup to an .STL file, the file type the printer prefers.

Open the .STL file in Accutrans 3D and you’ll be able to check if it’s watertight. The software will show, in red and green, problems with the model. You’ll have to go back and fix those in Sketchup and repeat the watertight check process until the model is deemed watertight. Once watertight, you “save with options” the .STL file in Accutrans 3D with Output Scale Factor (OSF) set to .1 size, to make up for working 10 times larger in Sketchup, and your model will be print-ready at the right size.

As long as you designed your model within the guidelines for the material you want your model printed in, your file will be ready to print.

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Fig. 3 Strong bridge. The bridge over the Palm River was printed using Shapeways’ White Strong Flexible plastic. It has a rougher texture than the material used on the hoppers, but that was acceptable to Alex for the bridge.
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Fig. 4 Material options. A sample of Shapeways materials (from left) stainless steel, White Strong Flexible plastic, Black Detail plastic, White Detail plastic, colored sandstone, alumide, and Transparent Detail plastic, are in a holder made of White Strong Flexible and Black Strong Flexible plastic.

Frosted Ultra Detail: $3.49/cubic centimeter + $5.00 setup fee
White Strong Flexible: $1.40/cubic centimeter + $1.50 setup fee 

Materials

There are different types of 3-D printers, and the different types of printers are fit for printing different materials, sizes, and levels of detail. In general, the cost of printing depends on the material used and the amount of material needed to print. For that reason, bigger scales mean bigger costs when it comes to 3-D printing. N scale and Z scale are the most cost-friendly.

I like a material Shapeways offers called Frosted Ultra Detail (FUD). The material provides great detail at an affordable price. Frosted Ultra Detail is a translucent white plastic, but brittle compared to the plastics commonly used in models. The maximum size of a model printed in FUD is 184 x 284 x 203 mm (length x width x height), or about 71⁄4 x 113⁄16 x 8 inches. I’ve used FUD to produce many N scale freight cars, seen in figs. 1 and 2, at about $15 to $25 per car, and I’m happy with the results.

Although FUD can produce great details, there’s still a fair amount of inconsistency in the printing process. A lot depends on how the model is oriented during printing. As a result, sometimes the 3-D printer spits out a wonderfully detailed and smooth model, and other times (most often) the model requires a bit of delicate sanding to smooth the printing ridges.

There are materials available from printers other than Shapeways that can produce smoother, higher-detailed models than FUD, but the price of those materials is much higher.

Frosted Ultra Detail models come with a waxy residue on them left over from the printing process. To remove it, I use Bestine. Also known as heptane, it’s used for thinning rubber cement and can be bought at craft stores such as Michaels, Jo-Ann Fabric, A.C. Moore, or Hobby Lobby.

I use a glass jar with a lid and pour in enough Bestine to cover the model. I let the model soak overnight with the lid tightly sealed, because Bestine will quickly evaporate. You can save and reuse Bestine many times. Soaking the model also changes the color of the plastic from translucent to a nice opaque white, a great surface for painting.

Another useful 3-D print material offered by Shapeways is called White Strong Flexible (WSF). It’s very strong, but not as detailed or smooth as FUD. White Strong Flexible has a bit of a grain to it that can’t be easily sanded away. Shapeways offers a polished version of WSF for a bit more money, but the polishing process changes the final size of the model.

I used WSF to make a model of the Palm River Bridge in Tampa, Fla. (see fig. 3.) The model bridge is so strong I could stand on it. And since the bridge was printed with precision, everything is perfectly square.

The 3-D print materials I’ve used the most are FUD and WSF, but there are many other materials available (see fig. 4). For example, you can print in sandstone, stainless steel, and a variety of plastics that offer varying degrees of strength, detail, and cost. Sandstone and WSF are the only material available from Shapeways in a range of colors.

Modeling the future

3-D printing appears poised to become a ubiquitous part of model railroading. Other than the easy precision and unlimited reproducibility, the best part of modeling using a computer is that in virtual space there is a handy feature called “undo.”

I can envision model railroading becoming more popular than ever thanks to 3-D printing. For one, 3-D printing makes model railroading a potential creative outlet for tech-savvy youth. Moreover, 3-D printing has the potential to make amazingly detailed modeling available to everyone regardless of skill, money, time, or space.

Alex Marchand is a writer, artist, and private investor. Alex models the phosphate mining region of Central Florida known as the Bone Valley. For more information on Alex’s 3-D modeling, go to his Bone Valley Modeler website at www.theuniverseas.com/bvmodels/

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