This quick and dirty coil winding machine was made from a few pieces of laser cut cheap 3/16" plywood, a nema 17 stepper motor, a 3-to-5 mm brass adapter, and a length of 3 mm threaded rod.
This repository contains the Fusion 360 model and the DXF files output from that, the Lightburn project I used to cut the wood, and the Arduino INO Sketch (program) that runs on an Arduino Nano.
The program allows one to stop and start and/or reverse the motor, count the number of turns the motor has made, and to program a certain number of revolutions to be performed.
- Laser Cut the wooden parts. I cut this 3/16" plywood in 2 passes at 95% power and 140mm per minute on my 10W diode laser cutter.
- Glue the three pieces together that make the "sliding part" and press a 3x9x4mm bearing into it.
- Glue the two pieces together that make the "base" and attach the Nema 17 Stepper Motor to the base with M3 machine screws.
- Add the 3-to-5 mm brass adapter and 3 mm threaded rod to it. When in use the sliding part is screwed to the base with two M3 x 8 wood screws.
The above photo shows the constructed machine in the process of winding a coil. I clamp it to my work surface and feed the wire in by hand.
The simple breadboard circuit consists of an Arduino Nano, a red A498 Stepper Motor Driver module, a 10K resistor, a 100uf 50V electrolyte capacitor, and a 4 pin long header to provide a connector to the stepper motor cable.
I used a 12V DC Wall Wart and a barrel connector to provide 12V to the high power rail, and the USB cable provides power to the Arduino (and a serial user interface) from my laptop.
The above photo shows the 12V coming into into the high power rail through the capacitor and connecting to the A498 module at the two upper left pins. The output of the module goes directly to a connector to the 4 pin cable to the stepper motor through the next four pins. The last two top pins are connected to 3.3V and Ground, respectively, from the Arduino via the lower 5V rail.
The bottom row of the 8 pins on the module are as follows:
- Arduino pin A4 is connected to pin1 on the module via the purple wire to to control the direction of the stepper motor
- pins 2,3, and 4, which set the micro-stepping rate of the controller are not connected
- pins 5 and 6 are connected together through the short orange wire
- Arduino pin A5 is connected to pin7 on the module via the yellow wire, with a 10K resitor to ground, to provide step pulses
- Arduino pin A6 is connected to the enable pin7 on the module via the green wire
The CoilWindingMachine.ino program makes use of the small myDebug library to provide serial port output with formatting and requires the installation of the Arduino AccelStepper library.
The program can be run from the Arduino Serial monitor or via Putty (better) to the COM port assigned to the Arduino.
The commands consist of a single character, possibly followed by a number and carriage return
The default revolutions starts off as 10, the default speed is set to 200, and the count of turns starts as zero.
- Pressing the space bar while the motor is not running will cause it to begin doing the programmed number of revolutions.
- Pressing the space bar while the motor is turning will cause it to stop at the next full revolution
- Typing Rnnn, where "nnn" is a number, followed by a return will program the number of revolutions
- Typing R-nnn, (where "-nnn" is a negative number) will program it to turn in the negative direction for that number of revolutions.
- Typing Tnnn, where 'nnn' is a number, will set the turn counter to the given value
- Typing Snnn, where 'nnn' is a number, will set the speed to the given value.
- Typing L (while the motor is not running) will lock or unlock the motor so that it can or cannot be turned by hand
It can be handy to lock and unlock the motor when messing with the coil.
The speed of 1000 is about as fast as my little nema 17 motors will go, but I typically just leave that at the default of 200.
The serial monitor shows the number of turns each 10 revolutions and when the motor stops.
Typically I use the default of 10 revolutions and press the space bar to start the winding the wire around the (tape covered) brass connector. I have learned it is important to keep the wire from touching the metal parts connected to the stepper motor as it appears to cause spurious turns and inconsistent behavior in the stepper motor if they touch. So I cover the brass part with masking tape before I further use masking tape to connect the initial lead of the coil to the brass part.
Then I insert the threaded rod and bobbin, attach the sliding part and do a few more presses of the space bar to wind the first 10-20 turns on the coil.
When I am more confident, I type something like "R50" to begin winding the coil 50 or more turns at a time.
Finally, when I am done winding as many turns as I want, I will remove the sliding part and the threaded rod with the bobbon, type "R-10" to reverse the direction, and press the space bar to unwind the inital leads from the brass part.
I used this coil winder in the Clock 1&2 and Clock 3 projects.