Train Tutorial
Making a Train...Start to Finish
Part 1 - Building Articulated Trucks
Part 2 - Building the Locomotive
Part 4 - Attaching Axles, Wheels, and Connectors
Part 1 - Articulated Trucks
Longer trains need moveable wheel bases to be able to comfortably negotiate tight turns and go up and over hills without running the risk cars becoming detached. The point at which trains need greater range of motion is four axles. The first two trains shown below have fixed (non-articulated) trucks and axles. Technically, the four axle locomotive can get around tight turns but it's a squeeze and it's annoying for whoever playing with it. Children will probably struggle with it and get frustrated. But hand crafting articulated trucks to comfortably accomodate four or more axles is, as you will see, quite a bit more complex than fixed trucks. So don't say I didn't warn you. The train with the red stripe is an example of articulated trucks which give the engine a nice range of motion.
Three axles don't need articulation.
A locomotive with four axles in a fixed truck (such as this one) looks nice but doesn't perform well around tight corners.
Articulated trucks don't look as authentic on steam powered locomotives but they perform much better on a track.
These images show the amount of articulation that can be achieved by the design in this tutorial. There's not a huge range of motion but it's enough to make all the difference.
Before we get started, here's a diagram to show all the relevant dimensions and measurements of the truck. I apologize that it is not more professional. Maybe someday I'll redo it in Google Sketch. Obviously, I am not a professional draftsman. IMPORTANT: For this train and this tutorial I will be using 3/32" brass tube axles. Some steps and measurements might change if you are using a different axle system. One other thing to note is that there is a slightly different axle system I've come up with that's not discussed in this tutorial. And even though this other method performs nearly as well a the axles of a commercially produced train, it's quite a bit more effort and--to be perfectly honest--not really worth it in my opinion. The system I describe in this tutorial performs pretty well.
I start with a 3/4" hardwood dowel because I'm lazy. If you have a table saw, almost any wood stock could be ripped down to size.
Measure 9/16" on the dowel. This is the height (at the apex) of the trucks we will be making. Cut it with a table saw.
The actual length of the individual trucks may vary depending on your specific design. I try to make mine as short and as compact as possible. I find that 1 5/8" is a good width.
Draw a line 1/8" from the bottom of the truck. This will mark the vertical center of the axle hole that will be drilled. Place a couple wheels on your truck to determine the horizontal positioning that suites your eye and mark that position as well. For a quick tutorial on drilling holes in wooden nickels (my preferred kind of wheels) go here.
A drill press is very helpful for this next step--though it's not required. Since I'm going to be using 3/32" brass tube axles I use a drill bit that's just slightly larger--7/64" in this case. I find a simple jig makes this next step easier especially if you are drilling a bunch of axles holes at the same time (assembly line style). My jig is just a flat piece of wood with two scraps glued down forming a perfect 45 degree angle. Then I place my work piece in the jig, align the drill to the first hole, and clamp the jig in place. That way I don't have to realign for every subsequent hole I drill. It also makes it so that you only have to measure and mark your first whole. IMPORTANT: the vertical positioning of your axles is critical. If you're off, even by a small amount, it will be noticeable later on. The train will still function fine even if the holes are not perfectly positioned, but the train will sit slightly askew.
On the top of the truck, draw lines with a ruler connecting the corners. This is a quick, easy way to find the center of the pice. Also, draw vertical and horizontal lines all going through the center. (I this case I forgot to draw the horizontal line at this step and ended up drawing it later.) So you should now have 4 lines crisscrossing the top of your truck.
At the end of this process I will be using #6 wood screws to attach the truck to the engine. The hole the screw passes through, however, needs to be big enough to allow plenty movement. I find that a 5/16" inch hole does the trick. Drill a hole all the way through the center of the truck.
The first picture illustrates what we are trying to achieve with the next step. Ultimately, I want to create a hole with two different diameters. The narrow portion of the hole needs to be wide enough for the shaft of the screw to pass through it and attach the truck to the engine. The wide portion of the hole starts at the bottom of the truck but does not go all the through to the other end (unlike the narrower hole we just drilled). I these pictures I've set the screw on the truck to help visualize it. We want to enlarge the small hole we just drilled (from the bottom) but we must leave about 3/16" (approximately) of material. The goal is to drill about as deep as seen here.
This is another benefit of a drill press. Even junky presses like mine have a way to set the maximum penetration depth. That way you can avoid accidentally drilling this larger hole all the way through the truck.
This is what it should look like after drilling the larger hole most of the way through. Note that the screw sits loosely and has some "play".
About half an inch from the center I mark another verticle line. At the intersection with the horizontal line I drill another hole which will hold the "limiting" peg. One end of this peg will be inserted into the top of the truck. The other end will extend into a space that will be drilled into the bottom of the engine and will restrict the motion of the truck. Without this peg the truck would be able to spin 360 degrees. Many different materials could be used for the peg: wooden dowel, cut off nail, a screw, etc. My choice is the same 3/32" brass tubing I use for axles. Drill a hole to a depth that will allow the peg to be well-seated but don't drill so deep that it will interfere with axle.
After the "limiting" peg hole has been drilled it is time to add some slope or camber to the top of the truck which will give it the ability to tilt up and down. Mark a horizontal line 1/2" from the bottom. Draw connecting lines from the edges to the apex. You could conceivably make the height of the truck at the ends more than 1/2" but you will not want to make it shorter because the circular magnet connectors are 1/2" tall. I remove the excess material using a disk sander. You could try to cut off the excess with a saw but that might be challenging. I would use a file before I used a saw.
Here's the result.
This is the 3/32" brass tubing I use for axles and, in this case, for my limiting peg. I put it in place then use a straight edge to give me an idea of how long to cut it. Note that when the truck is at its most extreme angle I want the peg to still remain inside the body of the engine.
The screw should fit loosely and the limiting peg should be snug. Don't glue the peg in yet. This is just for illustration.
The truck is almost done. Now we just need to drill a small hole into one end of the truck to receive the shaft of the furniture nail. First, connect the corners of one end to find the center then drill your hole. I suggest putting the magnet on the end that does not include the peg so that the holes drilled for the furniture nail and peg don't interfere with each other. The depth and width of the hole will vary depending on the size of your furniture nail. I usually drill a 1/16" wide hole that's roughly half an inch deep.
Here are a few last pictures to demonstrate what the final product looks like. Everything is loose fitted for the moment. I don't glue the magent, nail, and peg in place until after the truck is painted. Onto the next section where we will build the body of the locomotive!
Part 1 - Building Articulated Trucks