Tiny Town

There’s a lot of work completed, and now we’re ready for the work known as “finishing”. Why do they call it finishing, if we’re not finished building the engine? That’s a good question.

The answer is that we’re talking about putting a “finish” on the outside of all the metal parts, so they won’t rust… and also so it will look nice. Before we get to the pretty paint, though, we have to get the surfaces ready so the paint will stick to the metal.

The frame and boiler are first sprayed with a coat of grey primer. It’s important to get into all the corners, and especially the bottom parts.

When that’s dry, the black paint can be applied. It takes a lot of black paint to cover the boiler, frame, and some of the fancy fittings for the boiler.

Our project is starting to look more and more like a locomotive. Our next step is building the tender frame around the diesel engine. There’s a lot more work than meets the eye in this pictures, but as you can see, it is coming together beautifully.

Now it’s time to add the cab. You can see the temporary fasteners holding the roof in place — they are just like the ones used to build airplanes. The green boiler jacket, with its brass trim, has also been installed.

One of the features of this engine that should make it really nice to drive is the combination of a mechanical clutch and fluid drive. On the left, you can see the big toothed drive belt, like the ones they use for the supercharger on top fuel drag racers. The picture on the right lets you have an “engineer’s eye view” of some of the operating controls.

With the brass cab trim in place, it is looking more and more like what we all imagined back when we were looking at drawings on paper.

Many more weeks of work have been done, and now it is time to see things as they begin to take their final shapes.

Let’s start from the back, where some of the really heavy work has been done — fitting the completed engine assembly down into the frame. This shows the back of the tender area from right side. You can see the black air reservoir next to the radiaor.

The components of the fluid drive system have had custom shafting created to tie in to the clutch and final drive assemblies. You can just see the final drive shaft at the bottom of the picture. The pulleys and cog belt will complete that assembly.

Here’s the left side of the engine, which sits behind the engineer in the tender portion. You can see the large air compressor (light blue) and air piping. Just like full sized steam engines, this locomotive relies on compressed air systems for its braking.

Looking further forward, the steam dome and sand dome are completed, and the iconic diamond smokestack is also finished. The boiler jacket (the large shiny steel areas) and trim are all done, and ready to disassemble for a trip to the paint shop.

The builders plates are shown in place, curved to fit snugly to the smokebox. Notice the ornate brass flag standards and supports for the large headlight. The Mason locomotive designs were notable for their fancywork. Later locomotives were much more utilitarian in their design.

After months and months of work, the engine frame is lowered onto the driving wheel assembly and the tender truck, to check for precise fit and finish. The locomotive is then rolled back and forth without power a number of times, checking for proper suspension movement and other clearances.

Next, they remove all the accessories, trim, air tanks, air line plumbing, and drive train components, then they’ll move the frame/boiler assembly to another building for sand blasting.

It’s very exciting to see our dream getting so close to being a live locomotive!

You really start to realize how many parts make up a locomotive when you are making each one by hand. You also realize that one small mistake can mean starting all over to build a replacement part. So, they measure, measure again, check their measurements, and then have another workman re-check their work again.

The engine frame is the foundation that everything else depends upon to be straight and square. Here we see 1¼ inch thick steel plate being shaped by a cutting torch.

Next, the frame rails have to be heated and straightened until they are perfectly flat. See the big clamps holding everything in place?

It takes two identical pieces to make up the left and right sides of the engine frame, and the only way to get them exactly the same shape and size is to clamp them together and make all the finishing cuts and surfaces on both rails at once. It takes a big milling machine to do that!

This is an example of turning the wheels in a big lathe to make them exactly round, and also exactly the correct size.

Once the wheel (the inside part) is finished, the tire is put on the lathe and the inside of the tire is cut until it is just 8 one-thousandths of an inch smaller than the wheel. Why smaller?

The tire is heated with a “ring of fire” as you see in this picture, and heat makes it expand. You can see the wheel ready for the tire.

Then the workman, with very special gloves and tools, puts the hot tire over the wheel, where it cools and shrinks into its place, so it won’t get loose or come off.

One other very interesting operation is squeezing the axles into their wheels. The axle is finished to be just five-thousandths of an inch too big to go into the hole in the wheel. This is about the thickness of a human hair. Instead of heating the heavy wheels though, this time we use a very large hydraulic press to force the axle into the smaller hole on the wheel. It takes more than 70,000 pounds of pressure to squeeze the axle into the hole. That’s about as much as a fully loaded semi-truck!

Here we can see the wheels, bearings, and axle after they’re all pressed together, ready to be assembled to the frame.

Next we see the very beginning of the assembly of the tender frame and undercarriage. The tenders of the full sized Mason locomotives were made with oak timbers and strap iron, so that’s how this frame is made too. Next, the axle assemblies are added, then the equalizing springs that are the “suspension”.

There are many, many metal parts that need to be finished to their exact size according to the blueprints. This is a very important step, especially for the “running gear”: the valves, rods, slides, and other parts that move in order to make the locomotive run. The parts are assembled, sometimes several times, to be sure they fit exactly, before they are taken apart and powder coated, painted, or otherwise finished.

In another part of the shop the boiler shell is being built. Even though this engine won’t be powered by steam, the boiler still must look right, and that includes all the other parts that still must work — the smokestack, the bell, the sand dome, and other appliances.

It’s a striking change from the paint marks on raw steel to what we see here! Now it’s starting to look like the locomotives we all recognize from books and videos.

The distinctive “cow catcher” in the front of the engine is being built in a different part of the shop. You can see it here, while the workmen are checking to be sure of the fit. Yes, a cow catcher was an important safety device back in the early days of railroading, because a collision between and train and a cow could derail the train, possibly hurting many people. In the mountains, the cow catcher would also help to bump stray rocks off the tracks too.

It won’t be long now before we’re ready for testing the engine to be sure everything is perfect before we start final assembly.

One morning, after all of the molds are ready, the furnace is filled with scrap iron and turned on.

The man in charge of the furnace allows a little of the metal to run out into a hole dug in the dirt floor so he can judge the quality and temperature, and decide if the iron is ready. The hot iron is carried back from the hole to the furnace to be remelted. Foundrys have been good at recycling since long before most people had ever heard of it.

To move the hot liquid metal from the furnace to the molds, a big ladle is used. The ladle was pre-heated while the furnace was getting hot, so it helps keep the iron hot and easy to pour. It takes a whole crew to operate the ladle and actually pour the molds full of hot metal. They wear special safety clothing and face shields, and are very careful because liquid iron is very, very hot — around 2,400 degrees!

The ladle crew uses an overhead crane to move the ladle to the row of molds, and begins carefully filling each one. Even on a cool day this is really hot work.

After the iron has cooled, the molds can be opened, and the castings as they are now called, are dumped out to finish cooling. They have some of the sand clinging to them, as well as still being attached to the risers that guided the hot iron into the molded forms. You can see some “flash”, a little bit of metal that leaked out of the mold seam, on the lower left side.

When the castings are cool, they are cleaned up and trimmed, ready to move on to the next step in the process.

It takes a great deal of time to design and draw a new engine. There are a LOT of moving parts!

Once the design drawings are done, it’s time to make the construction drawings and get started with making patterns. Virtually everything that makes up the engine is made from scratch; the only pieces that can be found in a hardware store are the nuts and bolts.

When you’re making an engine from scratch, you have to make your own patterns, turn them into molds, pour them full of molten metal, then finish them down to a tolerance of only thousandths of a inch.

Most folks have never seen a foundry, especially the inside of one. Did you know the foundry floor is made of dirt? Let’s follow a typical part through the process.

First, a patternmaker reads the blueprints and makes a wooden pattern of the part. Because metal shrinks when it cools, the pattern can’t be exactly the size of the desired part. It has to be a little bigger. How much bigger? Well, that depends on the metal. Aluminum shrinks at a different rate than iron, and the brass for the bell has a different shrink too. For our iron brake wheel, the pattern is about 3/16ths of an inch per foot larger.

The pattern is painted in “foundry code”. Black is for the actual part, and red for the “cores” that make hollow parts of the piece. When the paint is dry, it’s ready for molding.

Making the mold is a little like making a sand castle. The mold maker uses special sharp sand inside a heavy frame, packing the damp sand tightly around the wooden pattern so that when the pattern is removed, a perfect impression of it stays in the sand. Of course, we need several identical castings from some patterns, like wheels, so the pattern gets used over and over. The molds are allowed to dry, then the two halves of the mold are clamped tightly together, and set up on the floor to wait for the day of the pour.

This is a very exciting time for Tiny Town, because we are getting a brand new engine for our trains. As you can imagine, scale-model engines are not someting you can just order from a catalog or website, so the process of designing and building a new engine takes a while.

First, we looked at lots of pictures of real locomotive engines from Colorado’s history. Then we picked out one that we thought was not only beautiful to look at but had historical roots in our mountains.

This is an old engraving of a “Mason-Bogie” style engine which was owned by the Denver, South Park, and Pacific railroad. The South Park was one of the largest operators of the Mason Bogie designs, as they were ideal for tough mountain roads with short curves and steep grades. Of course, the new Tiny Town locomotive won’t be named Breckenridge, but this should give you some idea of how grand this engine will be.

We contacted Uhrich Locomotive Works of Strasburg, Colorado, to design and build one of these beautiful engines for Tiny Town. They began work in 2011 with the many drawings and calculations that are required for such a machine. We will show you the progress of the engine as things begin to take shape.

Meanwhile, there are a few stories about working on these engines. You can read one of them here.

There is only one full sized Mason Bogie engine remaining in the United States. It can be found at Greenfield Village, part of the Henry Ford museum. Here’s a short video showing that engine operating.