8. Open source hardware: from fibers to fabric#

This week’s was pretty exciting for me. It would be the second group project of the course. For this week I wanted to try and create a thread wind-up machine. A thread wind-up machine is basically a miniature scale rope making machine. The idea came to me while I was ordering inventory for the lab. I was looking for conductive thread to order and came to the unfortunately realization that the popular conductive thread supplier Karl-Grimm does not ship to the USA. Karl-Grimm is one of the only suppliers that have solderable copper thread in the market. So instead of taking the loss I wanted to find an alternative way of obtaining solderable thread, which was making our own “conductive thread”. I found a good amount of inspiration for this week from these two instructable post, Conductive Thread Wind-Up and [“How to make Conductive Thread “] (https://www.instructables.com/id/How-to-make-conductive-thread/) . The concept behind making thread is pretty simple. The machine takes at a minimum two very fine wire/thread and combines them by spinning them together.

  1. Concept and Design
    when thinking on the design of the machine we found two cord making tools, Bradshaw Rope Maker and Leonardo Rope Machine. Using the conpects in these two machines we came up with a box designed that had a motor powered wheel with hooks that will be the combining mechanism on the machine.

  2. 3D Modeling in SolidWorks
    Quick 3D CAD designing in Solidworks

  3. Laser Cutting Pieces out of Acrylic
    we chose acrylic as the material for the box because we thought seeing the electronics inside the box would add an interesting aesthetic feature to the machine.

  4. Design Motor Shaft Coupler in SolidWorks
    The DC motor we planned on using has a very smooth motor shaft. We didn’t think simply press fitting the acrylic wheel onto the shaft would be secure enough to spin the wheel efficiently. So we decided to design a motor shaft coupling shaped as a star that would be press fitted into the center of the wheel. We used Solidworks to design the shaft coupler.

  5. 3D Print motorshaft and press-fit onto DC motor
    we used the MarkForge 3D printer to print this piece.

  6. Electronics Schematic Design

    Reference: source without going into the complexities of the MOSFET we can treat it as a switch. If we apply a potential to the Gate it will switch the current through the Source/Drain junction. So we connect the gate to the Arduino through a 220 ohm current limiting resistor to protect the Arduino. Then we connect the motor to the external power supply and the Drain of the MOSFET. We complete the circuit by connecting up the grounds. In this case the MOSFET controlling the motor is driven from Arduino Pin 9.

  7. Putting together the Electronics
    Picuture of Schematic Design From Website

  8. Programing the board with Arduino
    Reference: source

/*

Speed up the motor This example shows how to control the speed of a DC motor an LED on pin 9 using the analogWrite() function. This example based on the Arduino Example Fade sketch but modified to use timing instead of the delay() function

*/

int turns = 0; // how fast the motor runs

int turnAmount = 1; // how many turns the motor makes

unsigned long currentTime;

unsigned long loopTime;

void setup() {

// declare pin 9 to be an output:

pinMode(9, OUTPUT);

currentTime = millis();

loopTime = currentTime;

}

void loop() {

currentTime = millis();

if(currentTime >= (loopTime + 20))

{

// set the speed of pin 9:

analogWrite(9, turns);

// change the turnings for next time through the loop:

turns = turns + turnAmount;

// speed up or slow down the motor

if (turns == 0 || turns == 255) {

turnAmount = -turnAmount ;

}

if (turns == 0) {

delay(5000);

}

loopTime = currentTime; // Updates loopTime

}

// Other processing can be done here

}

  1. Assemble the wind-up box

  2. Wheel Hooks: Metal Parts of Binder-Clips
    The metal rods from binder clips can be repurpose to make the best hooks for our machine. Earlier when designing the wheel we made sure to create 4 slits that we can press fit the metal rods in to create hooks

  3. Hook up the electronics

  4. Wires and Thread
    For the wire we took jumper wires and removed the insulation from them, exposing the fine copper wire inside of them. For thread we used cotton sewing thread.

  5. Load and power the machine
    To load the machine we tied one end of each thread/wire to the hooks on the wheel. We then go to the other end and tie the 4 thread together. With the machine set up all that is left is turning on the machine and letting it do its thing.

  6. Conductive Thread Made! Time to test