Most of the copper wire sold have enamel coating, to make this train move, it has to be bare copper wires. And winding the copper wire is the most tricky part. The thickness of the wire not only determine how dense the copper coil could be but also the softness of the copper wire which determines how easy the coil the train could pass.
I first tested the copper wire with 0.05” diameter and AA battery. I was not able to make the battery move. I thought it was that wire is to thick but that was only part of the reason.
Then, I bought the wire with 0.02” diameter, this time the battery is moving, but because the wire is too soft and flexible, it was so hard to make a smooth path. After lots of testing and rewinding, I decided to use tape to constrain the copper coil.
In order to make the battery move, the magnet has to be Neodymium Magnets, as they are conductive and powerful. Also, the direction when winding the coil also matters. If winding counter-clockwise, according to the Right-hand grip rule, at both ends of the batteries, it needs north pole of the magnet. Otherwise, south pole for clockwise winding.
My original plan is to use a solenoid to hit something to make a sound. So I grabbed a solenoid and also bought five 1.5-3 v mini motors. My plan was to have two separate copper coil very close to each other, and connect the motor or solenoid to two copper coil, therefore when the battery is passing the connection point, the solenoid and motor will be triggered. However, as I mentioned, even I tried to make the copper coil as smooth as possible, the friction is still too big for the train to move completely to the next coil. It will just stop at the connection point, although the motor is moving as I expected.
Then, I came up with the idea to utilize the strong magnetic force of that Neodymium magnet. I tried hanging a Neodymium inside a glass cup. As you can see in the video, the magnetic force is powerful enough to move the hanging magnets. To get a better result, I tested and decided to use Coke glass bottles.
Then, I played around with bottle filling the different amount of water to make the sound with different tones.
The next step for this is to extend the length of the copper wire and tried to make a loop, therefore, I can have more bottles. I tried many times to build a loop, but because the wire I get was too soft, the electromagnetic train will stop at the corner. To make the coil above takes about 180 ft of copper wire. Sid and I probably had a speed around 4 hours to just winding the copper wires. And around 200 ft. copper wire is wasted for many reasons.