Tortuga: a better pickup winder

Slow and steady wins this race.  Even with a solid-state motor speed controller, I was unable to get the Spartan sewing machine to run slowly enough, in a reliable manner, and it kept breaking wires.  Not enough torque to overcome its own inconsistent friction, at such low power settings.

So, I built this stepper motor based winder.  555 oscillator drives A4988 stepper driver, running in 1/16 microstepping mode (i.e., the slowest, smoothest mode).  I built the "circuit board" from a piece of acrylic plexiglass, with holes drilled for the through-hole components (555, A4988, and 7805 regulator), and passive components wired point-to-point underneath.  I'm proud to say, it worked at first power-up, which is not always the case!

I have not yet built the spindle to attach to the shaft and hold the pickup bobbin; so far, I've just been testing the raw motor unit to make sure it can run for hours at a consistent slow speed, which it seems to do fine.  The one problem is that the A4988 gets awfully hot.  They come with a little aluminum heatsink, but this attaches with very flimsy double-sided tape, which doesn't seem like it has great thermal properties.  I think I will ditch the tape and go with cyanoacrylate, as I have done with some of my other stepper motor projects.

(Later:  Turns out, at least part of the problem was my failure to carefully adjust the torque setting on the A4988 module.  My usual procedure is to start with this control at about 50%, which always "works", but it's very important to adjust this setting specifically to fit the application.  In this case, I was able to dial it back to more like 25%, by setting it just above the point where I could easily cause the motor to skip steps by grabbing the shaft with my fingers.  This made the motor run much more quietly, and I suspect the A4988 will dissipate much less power, too.)

You can see one of my typical hacks here: straight segments of #20 solid wire create a perfectly adequate male 4-conductor "jack" for the stepper motor cable to plug onto.  Thus, I don't have to cut the cable, and things are more serviceable overall.  The excess cable length is rolled up and tucked under the circuit board.