Last night I was given an unpopulated stepper motor board, so I soldered a bunch of headers on it, attached my “Plan B” DRV8825 stepper controllers to it, and crimped up some custom cables. “Plan A” was to use Adafruit’s Stepper Shield to run two NEMA17 stepper motors, but after one caught on fire and a second just not seeming to pass enough current to the motor, I’m giving up on it and switching to the 8825 chips. The 8825s are sensitive to LC (inductive capacitive) voltage spikes from power leads longer than a couple of inches, and it’s strongly recommended to put a capacitor between VCC and ground as close to the 8825 as possible. This board neatly solves that problem by putting the capacitor right under the 8825 between the headers. I even color-coded the header pins for the different stepper motors and the inputs.
Here is a link to a short YouTube video of the laser in action. I have yet to get tired of watching it work. In this video, I’m cutting out v2 of my stepper motor mount for the new coiling machine. https://youtu.be/My6lsID7fZ0
I made progress last night on the coiling machine. I cut out all the parts I drew up yesterday. I machined a pulley out of delrin. I cut down the 16″ case-hardened stainless steel rod (no easy feat that) into two pieces so the carriage wasn’t overly long.
Below are some pictures of the process. It’s always fun to watch the laser cutter do its thing. The sliding carriage mechanism is so smooth it’s scary. I love it. I’m going to re-cut the pulley mount, there were inconsistencies in the Baltic Birch plywood (glue, or a knot) that the laser didn’t get through. Usually you can take a utility knife to the back and it’s easy to release the part, but this went half way through the plywood, so it’s ugly. Functional enough though.
I’m also going to redesign the motor mount. While it fits the NEMA17 brackets that I have, I realized it’s not stable enough without an additional side to lock everything down.
I would do this tonight, but instead I’m going to the Wulin Hanyu Shaolin Kungfu Martial Arts Show put on the by the University of Idaho’s Confucius Institute (孔子學院).
Last night I sketched idea after idea, and finally converged on a prototype for my new coiling machine. So I went over to the CAD station and drew up some plans. I will cut them out tonight from a sheet of 1/4″ baltic birch I picked up at lunchtime.
I don’t know what the final height of the carriage mount will be yet, hence the rectangular design sans location tabs. I put the two bars at a 30 degree angle. It’s just a guess at what I need, but seemed to make sense as 45 felt too sharp.
Tonight a machined a much bigger solenoid spool out of delrin. This one is 2.250″ long with a 1.250″ diameter. I’m going for a 900-turn coil with 22 AWG magnet wire, that should be stronger than my first coil. I expect to test it soon, and if it pans out I’ll set up my test playfield with both flippers.
One of the ideas I’ve had is for a self-leveling playfield. Basically you can wheel in in anywhere, hit a button, and even if the floor is uneven the table will balance itself right to left and set the angle of the playfield to the default (6.5 degree slope is what I have in mind). One interesting side effect is that I could programmatically change the slope of the game at any time. Perhaps make a game mode harder by raising the slope, or tilting to one side until the player makes a certain shot or the time runs out.
I was just given two Bosch seat recliner motors that will work perfectly for this feature! The two motors will sit under the upper corners of the playfield. The bottom center of the playfield will sit on a ball bearing and allow for adjustment left or right by the upper motors (since you only need three points to define a plane).
Well it’s still pretty early, and I won’t say definite yet, but I think I have finally come to a decision on the theme for this pinball machine. I’ll talk about it later, when things get more solidified. But this will help with the table design and features, plus it’s one less thing I have to (eventually) worry about! Yay!