In "Santa's Shop 2016" I used an O gauge train to run around the display--4 hours per day for 30 days. Two new engines failed (one motor came loose from the mount and ground down its worm gear, the other engine's "can motor" shorted a winding and quit). They were expensive and had a good "feel," but the "feel" was due to weights placed inside the engine, not quality parts.
So, If I'm going to deal with cheap parts, then I might as well choose my own parts and make something I can repair or replace. I used a Dagu dual shaft motor (about $8.00 from Jameco.com, part number 2150432) and various 3d printed parts.
I want the train to pull an illuminated Christmas tree (with twinkling lights), so I built this first stage prototype.
Something scrubs noisily (wheel against the frame?) and I'll have to figure that out. To get traction without a lot of weight on the engine, I put duct tape on the drive wheels.
Let's begin the construction.
If you examine the schematic, you'll notice a couple of diodes. The motor creates a bit of electrical noise and that noise (if not managed) prevents the leds from blinking.
In the ultimate version of this train, the coal car (salvaged from failed engines on my new train) has electrical pickup on the track and that will be the source of power for the motor and leds.
For now, there's a number of parts to print.
Use a couple of the printed "frames" to hold the motor. The wheels should screw into the plastic axle using 2-56 machine screws.
The front and rear connectors must be glued (or melted to the frame pieces).
The rear wheel is held in place with the axle holder (I melted this to the frame using a soldering iron).
The "shell support" was melted to the frame. Velcro was stuck to the top of the support (one sticky side to the "shell support" and the other sticky side will push to the "engine shell.")
To the back of the engine shell, I added the "hitch," which is designed to fit into the coupling mechanism of the particular coal car I am using.
For traction, I cut a thin strip of duct tape and applied it to each of the drive wheels.
I put the drive unit inside the shell. Press hard and the sticky side of the upper velcro sticks to the shell.
I used a "sticky side out" circle of duct tape to temporarily hold a breadboard to the coal car.
Since this is a "prototype of a prototype," I twisted wires together (rather than solder) and used duct tape to keep them from getting into trouble.
So, there's a scrubbing sound in the engine, no headlight for the engine, no electrical pickup utilization in the coal car, no voltage regulation, no "string" of lights for the Christmas tree, no Christmas tree, no miscellaneous train lights, nothing happening on the coal car--a long way to go before completion; but in concept, it works!