Category Archives: Portability

Sources of Inspiration and Materials

Want some inspiration for building lightweight yet rugged units? Look to the R-C Airplane modelers. They have been researching and developing methods for lightweight units for years. To say that they need to also be rugged is obvious. When is the last time you crash-landed your module from 100 feet?

The aircraft industry, mainly the Experimental Aircraft crowd is also a good resource. Not only can you gather ideas and construction techniques but their suppliers also carry many, if not most, of the more esoteric supplies you could need.

Fairbank AZ ? – Part 3 of many

I have had a serious set-back in the design of the Fairbank, AZ module. I have gotten totally immersed in the whole endo-skeleton idea discussed in The Origin of Portable Model Railroads: Or the Preservation of Favoured Techniques in the Struggle for Acceptance. The reason is that this also kind of supports the ideas in Something a Little Different.

Building a spine for a flat piece of track is one thing but the Fairbank module is, at least currently, supposed to be primarily a truss bridge over a river. This is going to call for a very different kind of spine that I have not even begun to figure out. Any ideas?

The Origin of Portable Model Railroads: Or the Preservation of Favoured Techniques in the Struggle for Acceptance

There are a few other Model Railroaders that I exchange emails with on a regular basis. Sometimes the most innocent remarks lead in interesting new directions.

We were having a discussion about buss wire size and feed wire size relative to layout size and control system. In other words we were re-hashing the old “how big should my wires be” debate. Now, all of us are of the “bigger is better” camp but the question comes up “How much bigger?” If you talk to different groups or even different control system manufacturers (read DCC for all our discussions), you will get several different answers.

Anyway, one of the guys decided to offer the tongue-in-cheek idea of using code 125 rail for the feeders brazed to a copper pipe filled with 10 gauge wire. Things digressed rapidly until one of the members offered that the idea was not as ridiculous as it first seemed. By using a pipe between the interfaces with fittings for the legs you could have truly free-form scenery.

So, a new thought to ponder in the never-ending quest for portability: should we build invertebrate or vertebrate units? Most (all?) of the portable units/modules I have seen have an exoskeleton. What about units with an internal skeleton and a flexible epidermis?

Darwin would be proud.

On Legs

Most modules are designed with four legs, one in each corner. A few designs use two legs on one end and rely on the legs on the next module to support the other end. These modules, without the addition of optional legs, do not stand on their own. There is even an innovative design with one leg per module that relies on the entire assembly of modules to provide stability. Obviously these modules do not stand on their own.

So how many legs should a module have?

Why three of course. Oh, and they should not be at the ends either.

Why three legs? For the same reason a tripod uses three legs. Three legs always touch the ground. How many times have you gone to eat and ended up at a table that wobbled? Tripods never wobble they merely tilt. Put a module on an uneven floor; on a module with a very sturdy frame, it will wobble just like a table; on a flexible frame, which is the vast majority of modules, the frame will flex to compensate for small variances and only wobble for large variances. Avoiding flex is the first step in maintaining solid and reliable modules.

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On Frames

The most basic part of a modular standard is the frame that supports the track work and scenery.

There are two basic designs that predominate in the design of frames for modules.

The first one is a simple box with a top and no bottom. The sides of the box are wood and the top used to be plywood but now is most likely foamboard. This is what Linn Westcott in his book How to Build Model Railroad Benchwork refers to as butt-joint benchwork.

The other design is two end plates attatched to a top plate and conformable side plates usually of masonite. It is also a simple box but has more free-flowing design capabilities.

What they share in common is that the frame is supposed to be fairly rigid to keep the track work at the proper angle to the floor and to other track work. The old frames with plywood tops were fairly rigid because you had a five sided wooden box with a lot of nails and/ or screws holding it together. The new style box is only four sided since the top is usually just plopped on. I see this all the time. The builder may put braces around the outside edge to keep the foam in place (and they think from sagging–but they are wrong) but rarely do you see any real cross-bracing or even “bed slats” to keep the foam from sagging. They flex and flop like a dead herring.

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Something a Little Different

For a long time now I’ve been thinking about a different approach to modular railroading.

I keep envisioning something like sectional track only in module form. Kind of like Kato Uni-track gone awry. The module would be track, roadbed, and a little scenery as standard but balloon out for scenes like a station, mine, what ever.

What I like about this idea is that it would be easier to transport the modules and because there is less scenery per module, the modules cost less to build, they would be lighter, and they should fit together with other modules with less obvious difference from module to module.

The problem I keep running into with this idea is that unless there is some control you also end up with all of the problems of sectional track: no easements (horizontal or vertical), possiblity of introducing S-curves, and easy to introduce wiring issues like hidden reverse loops.

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Materials

Most modules use wood as the primary framing material. The obvious advantages of wood are:

  • Cost
  • Availability
  • Familiarity
  • Ease of fabrication

It also has two disadvantages that I find overwhelming:

  • Environmental stability
  • Weight

While wood is readily available, easy to work with, and affordable my feeling is that wood is too heavy to be an ideal material for module construction and its environmental stability can cause issues. I live in Arizona, which is a semi-arid and warm (some would say hot) environment. Many of the friends I have in the modular world live in Ontario, an environment that is both wetter and cooler than Arizona.

If we built interface plates for our modules out of wood, me in Arizona, and them in Ontario, even if we were exact in our measurements, our interface plates would not be exactly the same when we met to build a temporary layout. Wood expands, contracts, warps, dries out, and is attacked by insects.

Because of this, I am looking into alternative materials and methods of constructing the frame work for modules.

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