Still Working

I was in Portland last Wednesday night through the weekend, so I didn’t make any progress during that time, but Monday (May 8th) evening I worked on a couple of flipper parts. First, I turned down the heads of two M6 bolts to fit the solenoid hole. The bolt heads are just a little bit too big to fit, but the lathe made quick work of that. Both bolts now are perfect fits, and both support and align the coil on one side as well as provide a stop for the armature to hit.


I needed new armatures to fit the new, bigger coils. I cut up some of the bars I previously milled (see 30 Apr 2016 heading here) and ground them down to the length I needed, which is to allow the mouth of the armature to protrude completely even when the coil is fully engaged, so the linkage doesn’t jam.


This week I have also drawn (in CAD) my flipper design to mill out of aluminum. I also have been working on the shaft that supports the flipper as well as the link that connects to the solenoid armature and allows the whole thing to turn. That link will also be milled from aluminum, and I designed it to look kind of like a miniature flipper. One side will fit over the shaft of the flipper and an M3 bolt will screw down into the shaft, holding it in position. The other side is designed to fit over the “bone” linkage I’ve already milled, though I’ll have to either design a shorter version or cut it down. Overall, these are the last few parts I need to finalize my flipper assembly and move on to the next part!

Flipper assembly

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.

Flipper assembly

I worked on a new design for a compact flipper assembly using my new solenoids. I’m still working things out, but have a prototype ready to try tomorrow. I’m thinking about a torsion spring for returning the armature/linkage back to it’s normal position. I may have to redesign my linkage piece to save space, too.


I coiled both flipper solenoids last night. Making this machine has been really eye-opening. First and foremost, I have to decide to either let the machine coil the wire the way it wants to and take my damn, dirty hands off it or I should make it more interactive with a way to pause and restart. My problem is I want a beautiful coil with wires stacked perfectly and it’s just not happening. Still, I’m way further than I ever was with my old machine. Here are some pictures from last night. As you can see, the main problem is at the ends of the spool.

Nit-picking issues aside, I’m really happy with the way these came out. And shy of doing it painstakingly by hand it’s the best I think I can manage.

My next step is to finalize how the flippers rotate, how to control where they should stop and start, and then get the new solenoid mount worked out and installed. I sense a new project in the near future: learning to make springs on the lathe!

New Spool

I made two new spools last night, setup/etc from start to finish took about an hour. As I make more I’m sure that time will come down. Just making the second one was much faster than the first. I am not super fast on zeroing my tools though. And well I probably shouldn’t be since I’m no professional. I take my time and try to get it all right the first time.

So here’s a picture of the new flipper spools I hope to coil tonight. I got a new shipment of black delrin rods 1.375 and 1.5 inches in diameter. These are 2.25″ long, 1.25″ diameter at the flanges. Center hole is 0.376″, the flanges are 0.100″ thick, and the spool walls are 0.112″. The tool in the picture is a reamer, .376″ diameter. I drill the center holes out with a 23/64″ bit, then use the reamer to open up the last 17 thousandths of an inch. It’s more accurate that way.

Working with the digital readout on the lathe has been real interesting. The Y axis (diameter) is set to the full size you are working with, not half of the diameter as I would have thought.


First New Coil

Last night I did some final tests and then connected my spool of magnet wire up and started a trial run of 10 turns. Everything went smooth, so I bumped the turns up to 890 and let ‘er rip. About 100 turns in, the carriage stopped moving 😦

After several more 100-turn tests, probing with the multimeter, and serial-debug from the Arduino, I determined that the DRV8825 was the culprit. I replaced it with a spare and was able to finish the last 200 turns without any trouble. Unfortunately, the winding wasn’t as pretty as I had hoped. That being said, it’s still better than the coils I made by hand on my old winding machine.

I also noticed that while I was moving the carriage exactly the diameter of the wire for every turn, sometimes the wire didn’t lie down that way, so I bumped the ratio down (from 60:1 to 55:1 coil-steps:carriage-steps) and that looked smoother.

The limit switches worked great, and you don’t have to be exact with them, which is nice. The wire seems to find its own way at the end of the spool.

Also, clamping the beginning of the wire between the spool and the neoprene washer was a great idea, it held that wire perfectly.

In the code, I used the name Coilatron 9000 for the machine, which is sticking so far.

Watch the video of my solenoid winding machine before it got all jacked up.