I'm going to be using two stepper motors, one the unipolar motor that comes with the Mega kit, and the other a bipolar Nema 17. I'm going to be building a guitar pickup winder. The Nema 17 will be used to just spin the pickup bobbin to wrap the wire. It will need to ramp up at the start, and decelerate at the end, so as not to snap the wire, or unroll a lot at the end that I'd need to clean up.
The other unipolar (or I could use the little servo) will be used to move the wire back and forth so the wraps lay down flat adjacent to each other.
They will need to coordinate with each other during the acceleration and deceleration. So, they will need to change their speed correspondingly together.
There are a few variables (wire gauge, number of wraps, bobbin width) that can be input at the beginning and left alone for the whole process. It's just that the speed needs to adjust with both motors at the same time.
Do I need to handle this all in one loop and adjust the speed with delay() values? Or can the two motors have values sent to them and they will both operate independently, just looking for signals from the loop?
That would require some sort of back pressure on the wire reel. I've been thinking of just having a sponge press against the reel. I don't think the tension has to be that tight, but I could be wrong. I'll have to research that. Any details you can offer would be great, if you've done this before. Hmmm....I did find this.... https://nebulaguitarparts.com/the-subtle-art-of-pickup-winding-how-tension-shapes-your-tone/
For drag/tension, two flat washers that you 'dish' then run a bolt through them and adjust the lock nut to apply the right tension as the wire passes between the two washers. Maybe two pieces of UHMW would be a better 'bearing' surface.
My coil winder used a serpentine of 4 non-turning fiber pulleys to control tension, but the original project only did a single layer of wire.
Your project will be multiple layers and will be a problem after the first layer as the new wire will nest between the turns of the previous layer. That problem will produce a pyramid type of winding. Your solution will be of interest. Good luck!
Have you done this? Seems like these abrasive materials would damage the insulation on the outside of the wire. It is not visible plastic insulation on the wire like you buy for prototyping. It's more of a very thin transparent coating. That's why I'm thinking something malleable like a cellulose sponge, with maybe something to adjust the pressure on the reel. Manually or programmatically.
Yes, build and learn. I'm trying to make the wire guide move back and forth at the right speed, based on wire gauge, so the wraps are close. But, I will see how feasible any of that is in the prototyping stage.
I have done something similar (except manufacturing precise spools of twine rather than wire). There is a device made specifically for providing consistent tension, which is used in any industrial equipment that requires such a thing. This is done by magnetic fields rather than friction. It is called a "hysteresis brake". Due to the lack of consumer demand for such things, they are not very readily available for one-off purchase. You can find used ones for sale on eBay though. Make sure the specs of the brake you purchase are appropriate for your application (they are available in a wide array of tension ranges).
You did not mention that it is enamelled wire. In that case, the friction-style tensioning is a bad choice for sure. But a sponge is the other extreme, think of something in between. Maybe even use a motor in generator mode as the friction device, IIRC, you can control its drag via the magnetic field.
more science!!!!! of course my geek self loves it, but i'm also sitting here trying to resurrect trig from 50 years ago too to solve an odd situation, and i feel like i'm trying to solve a three body gravitational problem.
I suspect that Amazon has no clue as to what is on the wire. Stay far away from enameled wire as it is likely to be old and brittle and will break and flake off the wire. It will be fine for your testing purposes, but get better wire for your production stuff.
I just looked at DIGIKEY and Remington Industries wire and there is NO MENTION of them using enamel on their magnet wire.
I used a Nema17 motor for the bobbin. I've used a micro stepper, lead screw and bracket from an old CD-ROM for the wire guide. The concept is the same: for every 200 steps (1 full rotation) the wire guide moves a pre-determined number of steps (equal to the wire width, dependent on wire gauge and what type of coil I am winding).
I have a potentiometer connected to an analog input, that produces a voltage that is translated into speed (actually delay, wired so that as you turn the pot clockwise, supposedly to increase speed, the voltage is going from 5 volts to 0, which in effect reduces delay and increases speed). You need to do a running count on millis to gauge your speed (millis won't block all operations like delay() will). The micro stepper runs full speed.
My wire tensioner is two steel washers with a bolt and butterfly nut, with felt pads affixed. The pads are about the size of a quarter: the kind of thing used on the bottom of chair legs so your chairs don't scratch your floor. I get 8 pads on a card for $1 at Dollarama.
To start, I input wire gauge and number of turns. I run my winder with speed set at ~70%. Despite what that pot is set at, the MCU still starts off slow and ramps up and then ramps down as the number of winds is being approached.
Good idea on the felt pads. I don’t yet understand some of the other stuff, and my phone is not letting me view your original message as I type. I don’t know what millis is, for one thing. Never mind. I looked up millis. After some calcs today I realized if I used two bipolar motors that have the same specs, and run a horizontal shaft with a glide block on it, I don't have to worry about coordinating speeds of each motor. Just direction changes of one of them.
of course my geek self loves it, but i'm also sitting here trying to resurrect trig from 50 years ago too to solve an odd situation, and i feel like i'm trying to solve a three body gravitational problem.