Traditional Model Railroading has been called by some the “World’s Greatest Hobby” – and not necessarily out of the normal sort of pride that one tends to have towards their passions. Model Railroading encompasses a very large amount of skills and interests, even beyond just scale modeling – electrical work, carpentry, machining and fabrication, paint, plastic and foam sculpting, and more. A lot has been done in the hobby to help make it easier to get into and make some truly impressive things without requiring an in-depth knowledge or steep learning curve to be learned by a single person, but it can still be very daunting for a person to pick up once they start looking into everything involved.

LEGO Model Railroading is similar to this in a lot of ways. Beyond just building a model that looks good, if you want to design and run a LEGO locomotive you will need to learn a lot more than just good building practices. There’s some dabbling in Technic, learning about gearing, learning about articulation and swing clearances – and that’s just for the locomotives! The amount of topics to learn grows greatly as you expand into a full layout.

People looking to get into LEGO Trains as a modeling hobby have a bit more of a challenge than they would going into something like HO or O Scale stuff – you have to build everything yourself, and LEGO doesn’t sell true Scale model kits. This leaves a bit of a gap for where to start – how can someone just coming in get to a point where they can have and run models that look as good as the custom stuff that caught their eye? This generally seems to be the point where people realize that there is a lot more to learn than there seemed.

Of course, there are always options outside of the LEGO company. There are a lot of great builders in the train community who have been sharing huge amounts of resources and information for years. Custom instructions for LEGO Trains and train-related models are becoming easier to find and many very-high quality ones are available as well, which can also help more with teaching techniques and getting people started with nice detailed models. 

Even with these available, there’s always going to be the desire to do something yourself. Maybe what you want isn’t available, maybe you just want to have the satisfaction or the skills to be able to do something like that on your own – and of course, there’s also those who love to learn new things for its own sake.

To help with this, I’d like to do a series covering how to build Scale Model LEGO trains – just the good, fundamental basics. A lot of this information may be common knowledge to more experienced builders, but my hope is to create a good starting point for new people coming into the hobby. By taking the many stages of good design in small, focused chunks we can examine each stage and learn some good practices and methods for dealing with the different phases of the design process. These are good starting points, but they are not necessarily definitive or even the best way to do it – They should let you get some good starting fundamentals. When building a model from instructions or mimicking techniques from more experienced builders, it can be relatively simple to see how something was built, but it’s good to know why it was done that way. Learning the fundamentals behind each of the design choices is a great way to get started towards great models.

That said, let’s cover the first, most fundamental topic of Scale Modeling.

Part 1: How to Scale

Almost every time “Scaling” is brought up in LEGO modeling, especially as it pertains to LEGO trains, it most commonly is focused on arguments on which scale is “Ideal”. 

Many builders want “Minifig Scale”, which is itself a messy, inexact science. The proportions of minifigures are out of whack in every way compared to a real human – and this means that there’s no way of scaling with them that works perfectly. In fact, there are many proper “scales” that work just fine with Minifigs, and it’s really just down to personal taste which way looks best.

Still, many arguments have been and will be had in regards to the “Proper scale” for LEGO Trains, and what this usually boils down to in practical terms is your preferred “Stud Width” – are you building in 8-wide? 10? 6 and a half, like a maniac? This conversation probably takes up the bulk of information to be found about “LEGO train scaling” on the internet, and I’d like to go a different route – let’s talk about how to actually scale.

Let’s assume you know approximately how large you want to build your engine/rolling stock. You’ve read a debate about stud widths (Once you’ve read one, you’ve read them all), you’ve seen plenty of pictures of builds in various scales, picked out one you’d like to try – but how do you actually get a LEGO Scale Model out of that choice? It’s numbers time.

In the US, the maximum allowed width for anything on the track (Also known as the Loading Gauge) is 10 feet, 8 inches. Most locomotives and freight cars are about 10 feet wide as a result. Using this information, you can get a rough range of scales to widths.

1:55 is approximately 7 Studs wide

1:48 is approximately 8 Studs wide

1:42 is approximately 9 Studs wide

1:38 is approximately 10 studs wide

Narrowing down your scale to a real number helps a lot, especially if you’ve got good reference material. A good scale drawing of a locomotive or freight car, or even just some measurements taken off a local engine with a tape measure, become incredibly helpful for building a scale model if you have your actual “Scale” decided.

There are tools for converting real-world measuring units into LEGO units of measure, e.g. Inches to Studs. My personal favorite was created and is hosted by a very prolific Technic builder, Sariel. This can be found at “Studs.sariel.pl”, and it’s generally as easy as inputting your desired scale and then your real-world unit of measure. 

For completeness’s sake, though, let’s go over the equations you’d need to do this without a tool. I’m going to use the “1/48” scale in the example, since that’s what I model in myself. If you’re working in Feet/Inches, I find it most helpful to convert it entirely to inches first.

Let’s use this scale drawing of an SD28. 

This engine is 10 feet, 3 inches wide. Converting that to inches gives us 123 inches wide. To convert this to our chosen example scale, simply divide that number by our scale, 48. 123 divided by 48 is 2.56, so a perfectly 1:48th model of the SD28 would be 2.56 inches wide. But how many studs is that?

A 1×1 Lego brick, which is what is really being referenced when people are measuring in “studs”, is 0.315 inches wide. So to finish our equation, we now simply take our scale inch measurement and apply the stud modifier by dividing one last time. 2.56 divided by 0.315 gives us 8.12, which means that our SD28 engine should be 8 bricks wide, approximately. LEGO doesn’t get down as fine in scale as 1/10th of a brick, so 8 bricks is a good compromise. 

Applying your scale

Of course, the real power of knowing how to scale isn’t in the width – it’s in the rest of the measurements. Once you apply this equation to other measurements, the proper size of the rest of the model very quickly comes together. Below, I’ve got a drawing of another EMD locomotive with some of the measurements converted over, one in 1/48 and one in 1/38.

This visual provides a lot of information. First, you can very easily see the size difference between the two different scales – the same detail on one scale will probably need a different build solution than it would on the other. 

Secondly, you will probably notice that none of these measurements come out to a perfectly even “LEGO Stud” count. No matter which scale you choose to build at, the LEGO medium is always going to present this challenge to you at some point. Sometimes you will be able to find a good way to hit these “uneven” numbers, but many times you’ll find that the most effective solution is to find a good way to round them to something easier to work with in the LEGO system.

The Art of Compromising

It’s very rare that you’ll be able to build a LEGO model where every single part is 100% in-scale. Advanced building techniques can get you close, but at the end of the day there are going to be compromises. Additionally, sometimes you can get a part that is technically more true to scale, but it looks blocky or visually confusing. A good model can use building techniques that are less “technically accurate”, but the result is more visually pleasing and makes the model “feel” more accurate in its execution. There really isn’t any good way to teach or explain this – but it’s something you’ll get a feel for as you build. If you hit a roadblock trying to get something scaled perfectly that looks good, see if you can come up with another solution that’s close enough. You can always come back and rebuild it later, after all!

Finally, keep in mind that the LEGO system’s limited set of parts can make the scaling of your details more tricky too. A part that works well to represent a detail in one location may not work well for that same detail in another. For example, a LEGO 1×1 round flower plate can work very effectively as a valve knob in the cab of a 1/48 locomotive, as seen here on Cale’s Blue Comet:

But, when used as a valve knob on the side of my similarly-scaled 4-4-0, the same size piece feels oversized, and distracts from the rest of the details around it:

In this scenario, I haven’t found a part that I think works well for a valve knob here, so it’s a detail that I’ve opted to leave off. That compromise, to me, keeps the model looking more true to the “character” of the real engine than having an oversized part that sticks out so much.

For dealing with compromises, I’d recommend that you identify the key features in the subject of your model: important details, shapes, or motions that stand out and get a feel for the “character” of it. If you’re building a steam engine, how far apart do the domes feel from the stack? Or the fans on a diesel? If you can’t get a perfect scale placement or size of a feature, understanding the character of the model as a whole can help you to find a more visually pleasing compromise.

At the end of the day, a good-looking LEGO scale model is a bit of a mixture of math and art. How much of each you use is up to you – find a balance between the two that you like. As you progress in your modelling skills you’ll be much better at finding good solutions, don’t worry about it too much if you can’t find the perfect solution when you are starting out. Many great LEGO train builders revisit old locomotive designs months or years down the line, making huge improvements with learned skills or new parts. If you aren’t happy with a compromise you have to make now, just keep it in mind or make a note of it – some day you’ll have a solution.