When someone mentions the words “dovetail jig,” my mind automatically conjures up boxes, but a dovetail jig can actually be used to join any two pieces of material together at right angles. This may well be on a box, but it could also be a drawer or, as in this case, parts for a toy train.
Two young girls who visit me several times each summer are very fond of trains, both riding on them and playing with them, so I came up with this design. It is not meant to be an authentic model in any way. It is just for the children to play with.
To make the building process easier, I used pre-made wheels and axles I bought online. The bumpers are also pre-made drawer knobs that I originally bought for a different project. The boiler’s funnel is the same knob, sanded flat on the top.
Please note that in these photos, I’m building two trains so each of my visitors will have one, but the Material Lists specify part quantities for just one train.
The first thing I did was make a boiler for each engine. I face-glued two pieces of maple together to create a thicker workpiece, then machined the blank down to 1-3⁄4″x 1-3⁄4″. From there, I installed a 45˚ chamfering bit in my router table and milled this piece into an equal-sided octagonal shape. I crosscut two pieces, 3″ in length, for the boilers. Use the same cutter to put a tiny chamfer on the front face of the boiler.
The next job is to make the bases. Since I built two trains, I needed eight of these bases, also made from maple. (One train, obviously, will only require four bases.) After you’ve trimmed the bases to size, they need rabbets cut into them. On half the quantity of your bases, there will be a rabbet at each end, but cut into opposite faces. These are the middle train cars. The other bases are for the engine and rear car. These only have a rabbet on one end; the other end receives the bumpers. Each of these rabbets should be about 3/4″ wide and 5/16″ deep. You need to allow enough clearance space for the cars to hitch together easily and swivel.
Also, in order to allow swiveling clearance, we’ll need to cut away some of the remaining material where we have created our rabbets. For this task, I used a simple sled on my table saw with a fence on it set at an angle of 30 degrees. I trimmed from the center of the bases outward to the edges to form gradual points. This will allow enough swivel for the trains to be steered during play. I then used a chamfer bit in my router table to just take all the edges off of the bases.
Drilling Holes in the Bases
Now the bases need some holes in them to accept the wheels, bumpers and the tow hitches. When I ordered the wheels, they were advertised as using 1/4″-thick axles, but in reality, their axle holes were exactly 1/4″. This influenced the drill bit size I chose for boring axle holes. The axles would need to be slightly smaller in diameter so the wheels could spin. Check your wheels and axles for hole sizing.
Drilling holes in small pieces of wood accurately is difficult, so I made three simple jigs for this. The first one is for the tow hitches. One end of it has a hole to fit the car’s hitch pin shaft, and the other end has a slightly larger hole so it can fit over a mating car’s pin. The bases fit snugly into this simple jig so I could drill the holes accurately and repeatedly.
The second jig drills the wheel axle holes. It’s just a piece of wood with the axle holes bored through it as accurately as possible and marked as sides 1 and 2. I glued a piece of scrap across the bottom to serve as a clamping point for my bases. Clamp a base to side “1” of the jig and drill two axle holes. Then, keeping the base oriented the same way up, clamp it to side “2” and drill the other side. The reason for using this jig is that, while a slight drilling error along the length of the bases would be unimportant to wheel function, the same error up or down would mean the finished train car would rock from corner to corner. The final jig is for drilling pairs of holes for the bumpers.
Building the Car Bodies
While I made my train car bodies from 3/8″-thick cherry, you can choose any contrasting semi-hard timber you like. The bodies of the middle train cars are 1-3⁄4″ tall by 4-3⁄4″ long. The end car body is 1-3⁄4″ tall by 5-1⁄2″ long, as it has no tow hitch to reduce its length. All the train car bodies have front and back sections that measure 1-3⁄4″ x 2-1⁄8″. This sizing allows the bodies to sit on the bases without protruding and catching on the wheels.
I joined these pieces with through dovetails cut on a router table jig, which has clamp holder attachments that make it easy to handle the small pieces. If forming the dovetails presents a roadblock, the pieces also would look great and be as functional by using box joints rather than dovetails.
After you’ve milled this joinery, cut and glue a floor inside the body of each train car. This way, once the bodies are glued to the bases, the floor provides a much stronger glue bond to resist roughand- tumble play. Round over the tops of the car bodies at the router table or by hand-sanding before assembly.
Constructing the Engine
Let’s return to the engine. First, we need to make the cab. This is just three pieces of maple dovetailed together. See the Material List for cab part dimensions. Drill a 3/4″ porthole into the cab front that’s centered between the top of the boiler and the roof. Now glue the cab to the base about 1/8″ in from the edge of the rabbet for the tow hitch. Next, make and attach the boiler support. I made mine from cherry and rounded over the front edge. Center and glue it on the width of the base and up tight against the cab structure. Spread glue on the bottom face of the boiler and glue it to the top of the support. Again, butt it tightly against the cab front. Last, cut a piece for the cab roof, and round over its top edges. Glue it to the top of the cab, positioning it for an even overhang.
Because young children can be quite rough with their toys, I reinforced the structure by installing two of the axle pieces — one up through the base and into the boiler and one from inside the cab into the boiler. These “pins” should help hold everything together for many years to come. At this stage, you can drill the funnel hole in the boiler and glue on the tow hitches, bumpers and engine funnel. The hitches are just shortened wheel axles. Glue them into place at the back of the engine and into the correct holes in the middle cars. The larger holes you drilled earlier in the other end of the train car bases should fit easily over the ends of hitches, to form a simple connection.
Adding the Finish and Wheels
It’s time for a finish! With young children come sticky fingers and other dirt that will soon ruin the look of the train. That’s why I decided a thinned coat of polyurethane would be the best protection. It’s also easy to brush or wipe on and dries fairly quickly. I applied two coats of this finish to all the train car surfaces and the wheels, sanding lightly between coats.
Finally, we can fit the wheels. I found the best way to do this was to slip the wheel over the axle up to the head of the axle and hold it there with one hand. Using a small brush, apply a thin film of glue onto the end of the axle protruding from the wheel. Then, holding the wheel at the head of the axle, slide the axle down into the hole. The cardboard is there to ensure that when the axle assembly is pushed fully home, there will still be a small gap to allow the wheel to spin freely.
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Hard to Find Hardware
7/32” Hole Maple Axles #28589
Don Phillips is a hobbyist woodworker and occasional contributor to Woodworker’s Journal. He lives in Spain.