Part 4: Rotatable Electromagnet Project

Send to Kindle

By Timothy Raney…Bald Engineer Guy with Glasses

Last week, we covered fabricating the electromagnet’s pole pieces. Now we’ll start fabricating the coil form discs and related work.

Coil Form Disc Fabrication
I completed the 2nd pole piece. Though this time, I kept the work-piece in the lathe chuck, turned the 1.2” diameter section and the pole face with its 60o chamfer (7/32” wide). I then cut-off the waste end, faced it to length, drilled/tapped its ¼-20 threads. The next task was cutting the phenolic coil form discs (X4). I cut the stock into five (5) 4.625” square phenolic pieces preparatory to drilling the center hole, roughing them on the bandsaw and final turning to ~4” diameter on the lathe. I cut an extra square “just in case”. Not that I ever make mistakes. I then stacked and clamped the squares, followed by drilling a 1” diameter center hole with a Forstner bit. I’ll do the final boring to 1.2” diameter later on the milling machine with a boring head. “Boring” in this context does not mean uninteresting, dull, dreary or even unexciting.

Coil Form Disc Fabrication
The next task was cutting the five (5) phenolic coil form discs into rough circular shapes before turning on the lathe to their final diameter. So, I began cutting the discs to shape with the phenolic squares stilled stacked and clamped from drilling the center hole. Since the material was clamped, I would remove one clamp, cut that part of the disc and repeat the process until done. The photographs show the process.

I completed the five (5) discs – 4-7/16” diameter and treated the edges with furniture wax. Afterwards, I worked on the paper for this project – the one you are reading now. I completed a few drawings and captioned photographs. This task is part of the process in keeping a shop notebook.


You will note in the ensuing narratives that I changed the pole piece minor diameter to 1” vice 1.2”. I felt that trying to bore the coil form discs was a little risky given my inexperience with boring heads. I know how this task is done, but I was not confident in my boring abilities at this point. So, I turned the pole piece minor diameter to ~1.0” to fit coil form discs. This task was straightforward lathe work - quicker and easier compared to setting-up a boring head on the vertical milling machine - at least for me. I’m done making more boring jokes or puns at this point.


Next week, we’ll continue this astounding series with fabricating the electromagnet’s yoke or frame. See you then!



This entry was posted in Electricity, Invention, Machine Shop, Magnetism, Physics, Projects. Bookmark the permalink.

One Response to Part 4: Rotatable Electromagnet Project

  1. Pingback: Part 5: Rotatable Electromagnet Project | Citizen Scientists League

Leave a Reply