Last night I wrote up a page and a half document about solenoids. I wanted to write it up in a way that a parent/child team could read through it and grasp the basics of how solenoids work. I explained a little about electromagnetic fields, how flipper solenoids work, and a few safety tips. This educational write-up will hopefully be a part of the starter kit documentation when it comes out.


The Pinball Expo

Last weekend I was at the Northwest Pinball and Arcade Expo in Tacoma WA at the Fast Pinball booth. It was a fun show (but so loud) and I have no voice left today at work. I realize that what I do is pretty niche stuff and not something most people are interested in, but I still got a lot of questions and comments about my custom stuff. Even my flippers, which I didn’t think much of, got some attention.

I’m excited to be working with the Fast crew, they are great, and have built a great community. My efforts here will shift somewhat as I assist them in preparing their pinball kit for launch, but stay tuned for updates. There will be new stuff coming down the pipes!


Tonight I finished up my flipper prototype by making a torsion spring. It’s not perfect, in fact it’s too strong but I only had one viable thickness (0.051″) music wire to use. I’ve ordered 0.031″ and will have it by the weekend. Which I won’t be home to receive, since this weekend is the Northwest Pinball and Arcade Expo in Tacoma. I will be taking my coiling machine and my flipper prototype, so all zero of you that read this blog should come out to see me.

Plunger Templates

I didn’t have as much time as I usually do, but I managed to model the plunger and its mounting plate in CAD. I cut some test pieces out of cardboard and the fit is great. I won’t be able to install it the way it’s meant in my current test table though, since it’s not a full-sized cabinet, but I’ll figure something out.

In case there’s any interest, my files are available on my GitHub repository.

Full Range of Motion

What does it take to get the full range of motion that I need? Marty was a big help yesterday at the end of the day, and put the flipper arm on the mill and showed me how to manually cut the slot at an angle that would allow the armature to move through the full intended range of motion. He also suggested trying to model the whole mechanism in CAD as that would show me problems like this before they are made. And he’s totally right. I modeled each part separately, but never even tried, even in 2D, to model them together. So I copied the components, changed them each to a separate color, and put them together in one file. Now I clearly see the change I need to make in the flipper arm file to support the motion that I require.


Ah, how cruel fate can be. My flipper arm slot doesn’t have enough depth to rotate through the entire range of motion that I need. I’m going to have to think about this for a little while. Not sure if I need to just cut deeper, with sharper entry/exit angles, or just come up with a different design.


Flipper Arms

Short of a better word to call them, that’s what I’ve named this part. They get attached to the linkage that attaches to the solenoid armature and do the actual turning of the flipper. I milled them out tonight, then found the length of the linkage part I need, 0.660″ on 1/8″ centered holes. I also need a longer M6 bolt, 30-35mm instead of the 25 that I have.

Anyway, the small hole is for a 3/32″ coiled spring pin to hold things together.