Table Saw Protection Using Brake Motor

Introduction:

• There are 60,000 table saw accidents a year, So we have an idea of a saw that can sense, react, and stop before the blade can cut your hand.
• we developed a saw that promises to save your fingers in the event of your hand touches the blade while it's running. The technology behind that activates a blade brake within a fraction of a second.

Block Diagram Of Table Saw Protection :

                                     https://www.youtube.com/watch?v=2LIDBMK2cj8

How It Works? :

• We use Capacitive touch sense to protection against the Table Saw.
• Capacitive touch sensing is a way of human touch sensing, that requires little or no force to activate. It may be used to sense human touch through more than a quarter of an inch of plastic, wood, ceramic or other insulating material (not any kind of metal though), enabling the sensor to be completely visually concealed. 
• Basically the arduino measures how much time the capacitor (i.e the touch sensor) takes to charge, giving it an estimate of the capacitance.The capacitance may be very small, nevertheless the Arduino measures it with accuracy. 

Watch a short video demonstration :  https://www.youtube.com/watch?v=u_dznopWYgU

Working of Table Saw Protection :

• The register is connected between arduino pin number 2 & 4 through Aluminium foil, By accidentally if your hand comes near to the blade ,the Aluminum Foil placed on the board senses the human finger and the changed Capacitance is measured by arduino uno and it will trip the relays, consequently motor starter energized so instant shut off the 3 phase Brake Motor.

PROGRAM OF CAPACITIVE TOUCH SENSE :

// Add the capacitive library and past below proram.

#include <CapacitiveSensor.h>

int led = 11;                                          //change '4 2' to any desired pin.

long time = 0;

int state = LOW;

boolean yes;

boolean previous = false;

int debounce = 200;

CapacitiveSensor   cs_4_2 = CapacitiveSensor(4,2);        // 10M resistor between pins 4 & 2, pin 2 is sensor pin, add a wire and foil

// To add more sensors...

//CapacitiveSensor   cs_4_6 = CapacitiveSensor(4,6);        // 10M resistor between pins 4 & 6, pin 6 is sensor pin, add a wire and foil

//CapacitiveSensor   cs_4_8 = CapacitiveSensor(4,8);        // 10M resistor between pins 4 & 8, pin 8 is sensor pin, add a wire and foil

void setup()                    

{

   cs_4_2.set_CS_AutocaL_Millis(0xFFFFFFFF);  //Calibrate the sensor. 

   pinMode(led, OUTPUT);

}

void loop()                    

{

    long total1 =  cs_4_2.capacitiveSensor(30);

    

    if (total1 > 150){yes = true;}          // sensing value

    else {yes = false;}    

    

    // to toggle the state of state

    if(yes == true && previous  == false && millis() - time>debounce){

      

       if(state == LOW){

         state = HIGH;

       }

       else 

         state = LOW;

         time = millis();     

       }

       digitalWrite(led, state);

      previous = yes;

      Serial.println(millis()-time);

      delay(10);

}

Watch video of table saw protection using brake motor :

https://www.youtube.com/watch?v=2LIDBMK2cj8

For more information about this project you can comment or mail me.
Mail id: rutvik1211@gmail.com

Brake Motor

Brake Motor : 

Brake Motor is combination of three phase Squirrel -Cage Induction Motor with Electro-Magnetic Disc Brake (A.C.) when power is switched off with ordinary motor, the Rotating part will stopped after some time but if brake motor is used rotating mass will stop Instantaneously.

• The electromagnetic brake is consists of liner plates (Brake Disc) with square hole at the center. One corresponding piece of square hub is supplied with the brake. This hub is keyed to the motor shaft and the liner plate is free on this hub.
• Normally liner plate is gripped between two discs with the help of spring pressure. They work on 415 Volt A.C. When the current is supplied on the brake, one disc is attracted by electromagnet against pressure and the liner plate is released. Thus the brakes are off.
• This creates an air gap between the liner plate and Magnet plate. The motor shaft is then released from braking to  run freely.
• When the voltage to the coil is shut off (the power is turned off) ,the Magnet plate is pressed against the Liner- plate by the spring  force to stop the motor shaft. 

Basic hall effect sensor project using arduino uno

                                       A Hall Effect Sensor is transducer that varies its output voltage in response to magnetic field.

Step 1 : components require

• Hall effect sensor (we use AH44E sensor)
• 10M resistor
• 3 wires for connection 
• Arduino uno
• any type of magnet       

Step 2 :

•     Resistor connect between pin 1(+vcc) & pin 3(digital output)

Step 3 : connection

connect sensor pin 1 to +5V pin of arduino  (Green wire)

connect sensor pin 2 to Gnd pin of arduino (White wire)

connect pin 3 of sensor to arduino 12 number pin (Red wire)

Step 4 : load program to arduino

Below program are paste in arduino programing


const int hallPin = 12;     // number of the hall effect sensor pin
const int ledPin =  13;     // the number of the LED pin
// variables will change:
int hallState = 0;          // the hall sensor status

void setup() {
  // initialize the LED pin as output:
  pinMode(ledPin, OUTPUT);    
  // initialize the hall effect sensor pin as input:
  pinMode(hallPin, INPUT);  
}

void loop(){
  // read the state of the hall effect sensor:
  hallState = digitalRead(hallPin);

  if (hallState == LOW) {  
    // turn LED on:  
    digitalWrite(ledPin, HIGH);
  }
  else {
    // turn LED off:
    digitalWrite(ledPin, LOW);
  }
}

Watch Video :