Last Wednesday (the 26th of April, 2017) I worked on some flipper assembly parts. After getting things together, I started working on how to a) get the right rotation out of my assembly; and b) make the whole thing as small as possible.
To do this, I put my new coil on a 12v power supply and gave it what it could, almost 3A! the armature got sucked in good, and the whole coil started heating real quick. So I connected a small inline scale and found that for about the first 1.25″, the pull was pretty even at 1.5 pounds. Once I pulled the armature out further, it dropped off drastically and popped out of the coil. So giving room for the armature stop in one side of the coil, I can use one inch of movement to rotate my flippers. Since I want to get 90° of rotation in one inch of pull, that means the arc can be scribed using a right triangle with a hypotenuse of 1″. Each leg would be 0.707″, and the distance from the center point of the hypotenuse to the endpoints of the other two legs would be 0.676″ away. That second point is the center of the shaft that rotates the flipper, and together with its bushing it’s 19mm in diameter (or 0.374″ radius). So there’s about .300″ from the outer edge of the bushing to the line where the solenoid is pulling. I should easily be able to make that work. This means, however, that the linkages I made way back when aren’t going to work, they’re all too long. Oh well.
So on to some pictures to look at. The first one is some parts laid out (and some old parts on the left there too). I’ll probably ditch the tapped aluminum bushing for a straight 3/4″ square bar now. The second picture is a side-by-side of my first coil vs my new coil (both resting on the same level surface). Bigger, stronger, faster. Oh yeah.