I’ve been working on a magnetic levitation project, and I needed an electromagnet. The electromagnet I made has about 600 feet of 24AWG magnet wire wrapped around a custom 3D printed spool, and has a low carbon steel laminated core.

First, I designed a spool to wind the electromagnet on and 3d printed it. See picture below:

Then I built a little LEGO Technic device to wind the magnet wire onto the spool (see it in action in the video).

Finally, I made a core for the electromagnet. The core of an electromagnet is the metal that the windings are wrapped around. The core allows the electromagnet to be much stronger. I made the core out of a 0.024in thick sheet of 1008 cold rolled steel. There were several reasons for this.

First, I wanted something as close to soft iron as possible because pure unhardened iron can’t be permanently magnetized (which is good for my application). 1008 cold rolled steel has very low carbon content (for steel), and because it is cold rolled it is mostly unhardened. I couldn’t find pure iron sheets or bars for a good price so this was the next best thing, and it works very well.

Second, I wanted a sheet of iron so that I could make what is called a laminated core. A laminated core is made out of thin layers of insulated metal to prevent the core form absorbing and wasting energy due to eddy currents when exposed to an alternating magnetic field. Picture the top of a solid metal cylinder as a wire coiled up. Just like a coil of wire, a changing magnetic field can induce a current (in this case called eddy currents) in the cylinder which then gets wasted as heat. By making the core out of layers, it is like making core out of lots of individual parallel wires that are not nearly as susceptible to eddy currents. I’m sure some site on google would be able to give a better explanation. Anyway, I insulated my layers by spraying them with hairspray.