I was asked how I'm going to replace all of the missing parts
I told you about before with just one stepper motor and a microcomputer.

Here's how.


This is the new totally electronic drive for my Model 20 coil winder.



The added parts are my stepper motor (under the big black gear) in the middle,
a matching rack gear mounted to the traverse rod for moving the traverse drive left and right,
two submicro sensor switches set up as a zero set 'axis home' stop (so the computer
knows where to stop the traverse), a blank PC protoboard for adding new control circuits,
and the Arduino's infrared LED rotation timing sensor. This sensor is the heart of the system...
its light pulses tell the Arduino not only when to tell the stepper motor to move the traverse
to properly wind the coil wire, but also control the main motor's speed
and also automatically shut itself off when the pickup's coil is full!

Want to learn how?

Read on



This photo shows the rack and pinion stepper motor drive that replaces all of the missing cams and gears.
The stepper motor drive gets timing pulses from the Arduino computer
that tell it when to turn on (move) the stepper motor, which direction to move it in
and how far it needs to go. The rack gear rides on the stepper motor gear and is attached
to the traverse rod so when the stepper motor turns the traverse rod moves back and forth
and the pickup's coil wire is wound neatly onto the pickup.

Where does the Arduino get its timing pulses from?

The infrared LED timing sensor at middle left.

This assembly takes the place of the first timing gear in the original drive. Basically, when this winder was new,
every time the main drive shaft rotated once, one wind of wire was deposited on the pickup coil,
the clock counter 'ticked' once, and the gear originally bolted to the shaft this assembly is now mounted onto
also turned once. This gear moved the other gears and the cam also in this gearbox
to move the traverse drive rod at the top of the photo.

Now, the very small black box is an LED infrared light emitter and detector setup,
sort of like the one in your TV's remote control or in a computer mouse. The silver shape is a shutter
that blocks the light from the LED in the top of the sensor from shining on the detector
in the bottom of the sensor for half of the mainshaft's rotation, and lets the light
shine through to the detector for the other half of the rotation. These alternating light/dark pulses
every time the shutter rotates over the detector makes a regular voltage pulse
that the Arduino can sense. These pulses tell the Arduino that the pickup is rotating
and how fast it's going, and the Arduino counts these pulses and uses this information
to control the rest of the winder's movements. Neato.

The two switches pressing onto the rack gear at the upper right will be zero count
or "axis home" switches for the Arduino. Since this winder is basically a counting machine,
closing these switches will tell the Arduino that this switch's point is 'zero' and the stepper motor
cannot move any farther to the left than it already is. This keeps the machine from crashing
(or damaging itself by going too far to the left).




This shows the infrared LED shutter assembly at its 'closed' or 'off' position.

When the silver shutter is in this half of its rotation, the light shining from the LED in the top of this sensor
is blocked from the detector in the bottom of the sensor so there is no voltage output from the detector.
If there is no voltage output from the detector, the Arduino doesn't do anything.



This photo shows the 'open' infrared light sensor with the light shining from the LED
on top of the sensor to the light detector at the bottom of the sensor.  I am using an infrared LED
for my sensor
so its light cannot be seen by humans.

When the silver shutter is in this half of its rotation, the Arduino sees a voltage at the input pin
connected to this sensor and knows that the main drive has rotated once - so it adds one count
to the total winds counter and also tells the stepper motor to move in the correct direction
a distance equal to one wire diameter.

For example... if the counter is originally at count number 100 and the diameter of the coil wire
you're winding is .005 inches (five onethousandths of an inch), the position of the traverse's stepper motor
 is "100 counts" or .500 inches from the 'zero' starting point (traverse moving from left to right
as you look at the winder). When this shutter piece rotates to this position the infrared light
shines on the sensor, which tells the computer to add one count to the total count (from 100 to 101)
and the stepper motor moves right from .500 inches from left zero point to .505 inches.
The computer continues doing this until it gets to the point corresponding to the other side of the bobbin,
and then the computer changes direction of the traverse motor only to move the traverse
back to the beginning of the pickup bobbin.




I am reusing this photo to show how this new infrared LED sensor and stepper motor system works.

In this original 1940's 'gear and cam' setup, every time the main motor rotates one rotation the mainshaft
and the pickup coil rotates once, the 'clock' counter moves one 'tick', and the blue timing gear
shown in this photo rotates once. The blue gear moves the green and yellow gears, which moves the red heart cam,
which moves the orange traverse assembly left or right to evenly wind the coil wire onto the pickup's bobbin.

In the Arduino system, the main motor still moves the mainshaft and the pickup coil you're winding
and the 'clock' still counts ticks. However... instead of the heart shaped cam we're using a stepper motor,
and instead of the blue main timing gear and its cam drive we use the silver shutter shown in the other photos
(mounted where the blue gear used to be) and the infrared LED sensor to make voltage timing pulses
 the Arduino can count. The Arduino counts these pulses and uses these pulses to control the stepper motor's
 speed and direction, main motor's speed and direction, and shut itself down when the pickup's coil is full.
Depending on the program the Arduino is running, any type of coil from a Tele rhythm pickup to a hot humbucker
or even Jazz or P Bass pickups can be wound with this machine!

Best of all, custom modifications to the pickups (like reverse winding or overwinding/underwinding the coil)
can be programmed in seconds!


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