Fab Academy at AS220 Labs

October 13, 2009 10:18 PM

Coil wrapping machine

by Shawn Wallace

wirewrapper.png

Pinball machines need a lot of coils. I realized that my first step in creating a pinball machine would be to build a tool to wind accurate coils. The pinball machine hobbyist scene is pretty well organized, so I quickly found this chart at pinballmedic.net detailing the various coil winding schemes that I will need:

Coil chart at pinballmedic.net

I had seen a booklet describing a homemade coil winder in Lindsay's Technical Books, but other than looking at that tiny little photo I did very little research into existing designs before sketching out the coil wrapping machine. The machine is based on a previously-designed microcontroller project called the Drawbot. It turns out I could use the drawbot board with a few minor changes to the firmware to achieve the coil wrapping machine. I wanted to only use materials I could find around the lab, which explains the...um...kind of hack look of the thing.

The mechanism is simple: one stepper motor spins the spool, one stepper moves an eyelet forward the width of the wire with each revolution. More complex winding algorithms are possible too, in theory.

We've spent a good amount of time getting a good 3D->2D->machine workflow going in the Lab. On the Mac, we've had some success with the free version of Sketchup with some SVG import and export plugins. We can now model things in Sketchup, export selected faces to SVGs, import to Inkscape and print directly to the laser cutter. here's a sample SVG export from the Sketchup file at the top of this entry:

wirewrapper.svg

We're working on finding a suitable STL export for Sketchup.

Next up in the project is making a flipper controller using coils wound on this machine.

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