Magnetic Arm Frame
Project Background

Many YouTube channels construct some intriguing technology for viewers’ entertainment and education. In 2015 I viewed a video made by a channel called Hacksmith, in which they made an electromagnetic arm attachment that could catch a replica of Captain America’s shield that they’d modified. I thought that the arm brace itself was the coolest part of the project and wanted to make my own just to be able to magnetically grab ferrous objects. I, like them, considered using some of my microwave transformers and their secondary windings as the driven electromagnets, but settled on mass-produced electromagnets instead because of aesthetics, efficiency, better-known load rating and ease of mounting.

During the summer of 2016, I got to work acquiring and welding scrap steel into a frame which I could attach to my arm. I used the arc welder that I had created earlier that year for all the welding tasks. After the frame was made I mounted it to an old soccer shin guard that I had kept, attached the electromagnets to the frame and wired them to a relay and momentary contact button in series with a toggleable switch to provide normally on or normally off settings, and connectors for the lithium-ion polymer batteries that would drive the circuit.

Unfortunately, just after I finished constructing my electromagnet arm brace, I broke my right arm, and I have since damaged two of the three batteries that I bought to power it. I plan to purchase new batteries and run it soon, at which point I will upload video of its usage. For short periods of time I can run 48 volts across the three electromagnets connected in parallel, which theoretically yields a holding strength of 2000 pounds at the surface of the magnets. I don’t have much of a real use for such a device at the moment, but strong electromagnets can often be useful, and I imagine that some random application will come up in the future for which it will be the perfect tool. I mostly just made it for fun, but every project is educational, so it was worth the effort.

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