Union Pacific Big Boy 4014 · A project story
Building the
Big Boy.
A legendary locomotive, around 600 wooden parts, and the project that took my laser-cut designs into more complex builds.
Published
Updated
01 / The inspiration
A legend I wanted to build.
I chose Big Boy for a simple reason: it’s a legend, and it looks incredible. The long boiler, the two groups of driving wheels, the rods running along its sides. There is so much to look at before you even get to the cab.
The real locomotive has a history to match. Union Pacific commissioned 25 Big Boys, with the first delivered in 1941. Their articulated frames allowed these enormous engines to negotiate curves. No. 4014 returned to service in May 2019 after a restoration, giving people another chance to see a Big Boy running. Union Pacific tells that story here.
My version brings that recognisable shape into plywood. At the scale for 3 mm material, the locomotive is 870 mm long. Even on a workbench, Big Boy lives up to its name.
02 / The wooden model
A bigger step in my own work.
I began with simple laser-cut designs. Big Boy was my first major step into much more complex models, with approximately 600 parts making up the locomotive.
That change is visible when you look closely. Layers of plywood give the wheels their depth. Long rods run alongside them, and the cab has an interior you can see through its open rear. The boiler, chassis and smaller details all have to come together in the finished shape.
This is the kind of project where the assembly becomes part of the attraction. You start with sheets of cut parts and gradually recognise the locomotive in the pieces on your bench. The included PDF instructions guide that process, but it is an advanced build worth spreading over several sessions.
03 / The matching tender
Big Boy and its tender.
On the real locomotive, the tender carries the fuel and water needed for the trip. Behind the cab, its long body completes the familiar outline of Big Boy.
The matching wooden model follows that shape, with Union Pacific lettering along the sides, rows of wheels underneath, and ladders at the ends. At the scale for 3 mm plywood, the tender is 388 mm long.
You can build the locomotive first and add its tender later. Choose matching material versions for both models so they sit together at the same scale. The tender files are purchased separately.
Explore the matching tender04 / In the workshop
On another maker’s workbench.
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YCR CutWorks takes the model through cutting and assembly in his own workshop. He looks at the labelled parts and instructions, sets up extra space for the sheets, and works his way towards the finished locomotive.
The video includes the practical difficulties too. He traces incomplete cuts to his laser’s mirror alignment and adjusts the holding tabs to make parts easier to remove. He also encounters tight joints after scaling the files for his plywood. These are useful reminders to test your material and settings before cutting a large project.
His verdict is clear: he enjoyed it as a hobby project, but felt that his assembly time made selling the finished model uneconomical. He reports about 16 hours over two days. That is one maker’s experience, rather than a promised build time, and worth hearing alongside his comments on the instructions and sturdy construction.
05 / Before you start
Give the build some room.
Read through the instructions before cutting, and leave yourself enough space to organise the parts. Keeping them in their labelled groups makes it easier to find the next piece as the assembly grows.
Measure your plywood and test the fit of a small joint first. Changing the scale affects the slots, tabs and overall dimensions together. The fit also depends on the material and the width of the laser cut, so a percentage alone cannot confirm that the joints will feel right.
I love seeing where these designs end up. Your build photos and reviews give me ideas for new models and the motivation to keep designing. If you make a Big Boy of your own, I’d be glad to see it.