How to make Arduino mini CNC plotter machine

Hello friends in this post we will see how to make mini CNC plotter machine using old scrap DVD drives, arduino & L293D motor shield.
In fact in past I have build some arduino mini CNC plotter machine or drawing machine in past.
But those projects are not well documented and unclear so I got many request to make a detail in depth tutorial about how to make arduino based mini CNC plotter machine.
So in this post I an going to cover all points like hardware assembly, code for arduino, processing GUI, G-code generation etc.
So before moving further let me brief you about what is CNC plotter machine is.

VIDEO

OVERVIEW

CNC plotter machine is basically a 2.5 axis CNC machine, it have two stepper motor on both X & Y axis and a servo motor at Z axis.
A pen is connected on Y-axis and Z-axis is used to make pun up & down.
As name suggest plotter machine obvious draw or plotting a drawing as per given instruction.
To give instruction to machine what to draw a special type of code called G-code is required.
Image will be converted to G-code with the help of special type of software.
afterwards this G-code sends to controller and controller commands motors how to move.
As result machine will draw image on paper.
Now lets we will see how to build such machine. starting with material list

MATERIAL LIST

Sr No.	ITEM	QTY
1	Scrap DVD Drive	2
2	Arduino UNO	1
3	L293D MOTOR SHIELD	1
4	MINI SERVO MOTOR	1
5	5V 1Amps POWER ADAPTER	1
6	SOME WIRES FOR MOTOR CONNECTION	—-
7	NUT AND BOLTS AS REQUIRED	—-

SOFTWARE LIST

1	ARDUNIO IDE
2	PROCESSING IDE
3	INKSCPAE VERSION 0.48.5

Please download the software from above link, and install them on your PC.

CODE AND LIBRARY

1	CNC CODE FOR ARDUINO
2	GCTRL PROCESSING CODE
3	AFMOTOR LIBRARY FOR ARDUINO
4	Makerboat Gcode Inkscape extension

“CNC CODE FOR ARDUINO” needs to be upload on arduino.
“GCTRL” needs to be open in processing software.
“AFMOTOR” library need to add in arduino IDE
how to do all this ? we’ll see further.

MACHINE ASSEMBLY

Step 1.

To make Arduino based mini CNC plotter machine obviously we need two scrap DVD drive.
I purchased this drive from local computer repairing shop in less then 1$ .
we’ll going to use its stepper motor along with sliding mechanism
here note that not all DVD drives have stepper motor in it. if the motor have 4 wires it means it is a stepper motor.
if you not found any 4 wire motor in DVD drive then it is use less.

Step 2.

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I quickly unscrew the DVD drive case with the help of screw driver and by applying some force I take out the stepper motor mechanism from the DVD drive case.
In this way I have two stepper driver mechanism and two empty case of DVD drive.

Step 3.

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After taking out stepper motor mechanism I cut the default motor connector strip with the help of scissor.
then I bring some DuPont 4 wire of around 40 cm and cut it into 2 pieces one for each stepper motor connection.
Then I strip the wire carefully without damaging the copper strain of wire.
and solder it to the expose terminals of stepper motor.

Step 4.

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Step 5.

Here I have paint the the empty case of DVD drive using gray shade spray paint, this step is not compulsory its ok if you don’t want to paint them.

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Then I used a piece of 20 x 20 mm aluminium angle to make holder for X-axis and Y-axis .
I drill the 5mm hole on the aluminium piece and cut it into two piece of clamp, further I use this clamp to fix the both axis with the help of M5X10 nut and bolt.

Step 6.

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Now I am marking for hole on DVD drive case to make arrangement for mounting for both stepper motor mechanism.
I carefully drill the hole of 5mm with the help of drill machine.

Step 7.

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After drilling the hole in DVD drive case I fix the four M4 X 60 nut bolts at the four corner of stepper motor mechanism.
Now I placed the stepper motor mechanism to its place and secure all four bolts with M4 nuts.

Step 8.

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This the is most important step in making mini Arduino CNC plotter machine here we are making pen up and down mechanism.
First I take a compass and carefully remove its pen holder part.
then I used a simple pen with top and bottom openable.
first take out the refill of pen and cut about 2 cm part from the top of the refill.
now I place a spring at the top of the refill which I have salvage from other trigger type pen.
then I used a strong thread and tied it to the center of the refill and secure it with super glue on to its place.
now I make a small hole just above from the center of pen body.

Now I carefully place the refill inside the pen and passed thread outside from the hole.
In this way I made my pen up down mechanism, when I pull the thread pen refill push upward and when I release the thread refill went down.
and due to the spring attached at top of the refill pen tip will maintain a good friction with paper..
Pen is now placed in pen holder and glue it with super glue on the X-axis

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I attached a mini servo at X-axis and tie the thread with the knob of mini servo motor.

Step 9.

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I drill four hole on the back side of machine and screw four 15mm spacer to mount arduino UNO onto it.
L293D motor shield is mounted on Arduino UNO.
In this way assembly of Arduino CNC plotter machine is competed now we will see the wiring

WIRING

We are using Arduino UNO as a brain of CNC machine, as we know there is stepper motors used in CNC machine.
Stepper motors are not easy to control so here we are using a L293D motor shield to control our stepper motors and one servo motor is used for pen up down movement.

Before start wiring first we nee to the know the correct wire of stepper motor.
Our stepper motor have 4 wire and stepper motor have two coils means the a set of two wire is form one coil.
so we need to find out which two wires are from one coil, so here I am using multimeter keeping multimeter on continuity test.
I connect the mutimeter prob to the wires one by one, if I get continuity( few ohms) between any two wires means that both wires belong to single coil and rest two are from other coil.

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Don’t forget to remove that yellow jumper, and connect the stepper motor wires as shown in drawing above.
and also connect the servo motor at servo 1 terminal of L293D Motor shield.
You need a power adapter to feed power to the machine, you can use 5VDC 1amps power adapter.
In this way wiring is completed now we can move towards arduino code uploading process.

ARDUINO CODE

Hope you have downloaded the arduino code and library from above in post if not, don’t worry you can download it from the below links.
Arduino code
AFMotor Library
First of all we need to install AFMotor library in arduino IDE if you dont know how to add library just google it.

Now simple upload the code without changing anything

Here I am explaining some important part of code which may useful for you

Followings are the servo up down values Increase or decrease if required. if servo works in opposite direction switch the value of punZUp & penZDown values.

// Servo position for Up and Down 
const int penZUp = 120;
const int penZDown = 50;

Below are the value to change the speed of cnc plotter machine youcan change the the value of StepDelay from 0 to 2,
0 is for maximum speed and 2 is for minimum speed, ideally keep it at 1.

float StepInc = 1;
int StepDelay = 1;
int LineDelay =0;
int penDelay = 50;

If your plotting area is bigger then you can change the Xmax & Ymax value from here.

float Xmin = 0;
float Xmax = 40;
float Ymin = 0;
float Ymax = 40;
float Zmin = 0;
float Zmax = 1;

Complete Code for arduino Mini CNC plotter mahcine

#include <Servo.h>
#include <AFMotor.h>

#define LINE_BUFFER_LENGTH 512

char STEP = MICROSTEP ;

// Servo position for Up and Down 
const int penZUp = 120;
const int penZDown = 50;

// Servo on PWM pin 10
const int penServoPin =10 ;

// Should be right for DVD steppers, but is not too important here
const int stepsPerRevolution = 48; 

// create servo object to control a servo 
Servo penServo;  

// Initialize steppers for X- and Y-axis using this Arduino pins for the L293D H-bridge
AF_Stepper myStepperY(stepsPerRevolution,1);            
AF_Stepper myStepperX(stepsPerRevolution,2);  

/* Structures, global variables    */
struct point { 
  float x; 
  float y; 
  float z; 
};

// Current position of plothead
struct point actuatorPos;

//  Drawing settings, should be OK
float StepInc = 1;
int StepDelay = 1;
int LineDelay =0;
int penDelay = 50;

// Motor steps to go 1 millimeter.
// Use test sketch to go 100 steps. Measure the length of line. 
// Calculate steps per mm. Enter here.
float StepsPerMillimeterX = 100.0;
float StepsPerMillimeterY = 100.0;

// Drawing robot limits, in mm
// OK to start with. Could go up to 50 mm if calibrated well. 
float Xmin = 0;
float Xmax = 40;
float Ymin = 0;
float Ymax = 40;
float Zmin = 0;
float Zmax = 1;

float Xpos = Xmin;
float Ypos = Ymin;
float Zpos = Zmax; 

// Set to true to get debug output.
boolean verbose = false;

//  Needs to interpret 
//  G1 for moving
//  G4 P300 (wait 150ms)
//  M300 S30 (pen down)
//  M300 S50 (pen up)
//  Discard anything with a (
//  Discard any other command!

/**********************
 * void setup() - Initialisations
 ***********************/
void setup() {
  //  Setup
  
  Serial.begin( 9600 );
  
  penServo.attach(penServoPin);
  penServo.write(penZUp);
  delay(100);

  // Decrease if necessary
  myStepperX.setSpeed(600);

  myStepperY.setSpeed(600);  
  

  //  Set & move to initial default position
  // TBD

  //  Notifications!!!
  Serial.println("Mini CNC Plotter alive and kicking!");
  Serial.print("X range is from "); 
  Serial.print(Xmin); 
  Serial.print(" to "); 
  Serial.print(Xmax); 
  Serial.println(" mm."); 
  Serial.print("Y range is from "); 
  Serial.print(Ymin); 
  Serial.print(" to "); 
  Serial.print(Ymax); 
  Serial.println(" mm."); 
}

/**********************
 * void loop() - Main loop
 ***********************/
void loop() 
{
  
  delay(100);
  char line[ LINE_BUFFER_LENGTH ];
  char c;
  int lineIndex;
  bool lineIsComment, lineSemiColon;

  lineIndex = 0;
  lineSemiColon = false;
  lineIsComment = false;

  while (1) {

    // Serial reception - Mostly from Grbl, added semicolon support
    while ( Serial.available()>0 ) {
      c = Serial.read();
      if (( c == '\n') || (c == '\r') ) {             // End of line reached
        if ( lineIndex > 0 ) {                        // Line is complete. Then execute!
          line[ lineIndex ] = '\0';                   // Terminate string
          if (verbose) { 
            Serial.print( "Received : "); 
            Serial.println( line ); 
          }
          processIncomingLine( line, lineIndex );
          lineIndex = 0;
        } 
        else { 
          // Empty or comment line. Skip block.
        }
        lineIsComment = false;
        lineSemiColon = false;
        Serial.println("ok");    
      } 
      else {
        if ( (lineIsComment) || (lineSemiColon) ) {   // Throw away all comment characters
          if ( c == ')' )  lineIsComment = false;     // End of comment. Resume line.
        } 
        else {
          if ( c <= ' ' ) {                           // Throw away whitepace and control characters
          } 
          else if ( c == '/' ) {                    // Block delete not supported. Ignore character.
          } 
          else if ( c == '(' ) {                    // Enable comments flag and ignore all characters until ')' or EOL.
            lineIsComment = true;
          } 
          else if ( c == ';' ) {
            lineSemiColon = true;
          } 
          else if ( lineIndex >= LINE_BUFFER_LENGTH-1 ) {
            Serial.println( "ERROR - lineBuffer overflow" );
            lineIsComment = false;
            lineSemiColon = false;
          } 
          else if ( c >= 'a' && c <= 'z' ) {        // Upcase lowercase
            line[ lineIndex++ ] = c-'a'+'A';
          } 
          else {
            line[ lineIndex++ ] = c;
          }
        }
      }
    }
  }
}

void processIncomingLine( char* line, int charNB ) {
  int currentIndex = 0;
  char buffer[ 64 ];                                 // Hope that 64 is enough for 1 parameter
  struct point newPos;

  newPos.x = 0.0;
  newPos.y = 0.0;

  //  Needs to interpret 
  //  G1 for moving
  //  G4 P300 (wait 150ms)
  //  G1 X60 Y30
  //  G1 X30 Y50
  //  M300 S30 (pen down)
  //  M300 S50 (pen up)
  //  Discard anything with a (
  //  Discard any other command!

  while( currentIndex < charNB ) {
    switch ( line[ currentIndex++ ] ) {              // Select command, if any
    case 'U':
      penUp(); 
      break;
    case 'D':
      penDown(); 
      break;
    case 'G':
      buffer[0] = line[ currentIndex++ ];          // /!\ Dirty - Only works with 2 digit commands
      //      buffer[1] = line[ currentIndex++ ];
      //      buffer[2] = '\0';
      buffer[1] = '\0';

      switch ( atoi( buffer ) ){                   // Select G command
      case 0:                                   // G00 & G01 - Movement or fast movement. Same here
      case 1:
        // /!\ Dirty - Suppose that X is before Y
        char* indexX = strchr( line+currentIndex, 'X' );  // Get X/Y position in the string (if any)
        char* indexY = strchr( line+currentIndex, 'Y' );
        if ( indexY <= 0 ) {
          newPos.x = atof( indexX + 1); 
          newPos.y = actuatorPos.y;
        } 
        else if ( indexX <= 0 ) {
          newPos.y = atof( indexY + 1);
          newPos.x = actuatorPos.x;
        } 
        else {
          newPos.y = atof( indexY + 1);
          indexY = '\0';
          newPos.x = atof( indexX + 1);
        }
        drawLine(newPos.x, newPos.y );
        //        Serial.println("ok");
        actuatorPos.x = newPos.x;
        actuatorPos.y = newPos.y;
        break;
      }
      break;
    case 'M':
      buffer[0] = line[ currentIndex++ ];        // /!\ Dirty - Only works with 3 digit commands
      buffer[1] = line[ currentIndex++ ];
      buffer[2] = line[ currentIndex++ ];
      buffer[3] = '\0';
      switch ( atoi( buffer ) ){
      case 300:
        {
          char* indexS = strchr( line+currentIndex, 'S' );
          float Spos = atof( indexS + 1);
          //         Serial.println("ok");
          if (Spos == 30) { 
            penDown(); 
          }
          if (Spos == 50) { 
            penUp(); 
          }
          break;
        }
      case 114:                                // M114 - Repport position
        Serial.print( "Absolute position : X = " );
        Serial.print( actuatorPos.x );
        Serial.print( "  -  Y = " );
        Serial.println( actuatorPos.y );
        break;
      default:
        Serial.print( "Command not recognized : M");
        Serial.println( buffer );
      }
    }
  }



}


/*********************************
 * Draw a line from (x0;y0) to (x1;y1).
 * int (x1;y1) : Starting coordinates
 * int (x2;y2) : Ending coordinates
 **********************************/
void drawLine(float x1, float y1) {

  if (verbose)
  {
    Serial.print("fx1, fy1: ");
    Serial.print(x1);
    Serial.print(",");
    Serial.print(y1);
    Serial.println("");
  }  

  //  Bring instructions within limits
  if (x1 >= Xmax) { 
    x1 = Xmax; 
  }
  if (x1 <= Xmin) { 
    x1 = Xmin; 
  }
  if (y1 >= Ymax) { 
    y1 = Ymax; 
  }
  if (y1 <= Ymin) { 
    y1 = Ymin; 
  }

  if (verbose)
  {
    Serial.print("Xpos, Ypos: ");
    Serial.print(Xpos);
    Serial.print(",");
    Serial.print(Ypos);
    Serial.println("");
  }

  if (verbose)
  {
    Serial.print("x1, y1: ");
    Serial.print(x1);
    Serial.print(",");
    Serial.print(y1);
    Serial.println("");
  }

  //  Convert coordinates to steps
  x1 = (int)(x1*StepsPerMillimeterX);
  y1 = (int)(y1*StepsPerMillimeterY);
  float x0 = Xpos;
  float y0 = Ypos;

  //  Let's find out the change for the coordinates
  long dx = abs(x1-x0);
  long dy = abs(y1-y0);
  int sx = x0<x1 ? StepInc : -StepInc;
  int sy = y0<y1 ? StepInc : -StepInc;

  long i;
  long over = 0;

  if (dx > dy) {
    for (i=0; i<dx; ++i) {
      myStepperX.onestep(sx,STEP);
      over+=dy;
      if (over>=dx) {
        over-=dx;
        myStepperY.onestep(sy,STEP);
      }
    delay(StepDelay);
    }
  }
  else {
    for (i=0; i<dy; ++i) {
      myStepperY.onestep(sy,STEP);
      over+=dx;
      if (over>=dy) {
        over-=dy;
        myStepperX.onestep(sx,STEP);
      }
      delay(StepDelay);
    }    
  }

  if (verbose)
  {
    Serial.print("dx, dy:");
    Serial.print(dx);
    Serial.print(",");
    Serial.print(dy);
    Serial.println("");
  }

  if (verbose)
  {
    Serial.print("Going to (");
    Serial.print(x0);
    Serial.print(",");
    Serial.print(y0);
    Serial.println(")");
  }

  //  Delay before any next lines are submitted
  delay(LineDelay);
  //  Update the positions
  Xpos = x1;
  Ypos = y1;
}

//  Raises pen
void penUp() { 
  penServo.write(penZUp); 
  delay(penDelay); 
  Zpos=Zmax; 
  digitalWrite(15, LOW);
    digitalWrite(16, HIGH);
  if (verbose) { 
    Serial.println("Pen up!"); 
    
  } 
}
//  Lowers pen
void penDown() { 
  penServo.write(penZDown); 
  delay(penDelay); 
  Zpos=Zmin; 
  digitalWrite(15, HIGH);
    digitalWrite(16, LOW);
  if (verbose) { 
    Serial.println("Pen down."); 
    
    
  } 
}

As of now code is uploded its time to generate G-code

G-CODE GENERATION

To draw something with CNC plotter machine we obviously needs G-code,
G-code is the language of CNC machine.
In this project we are using Inkscape software and makerboat G-code library to generate G-code of image.
First off all download the Inkscape 0.48.5 version and download the makerboat gcode extension.
Install the Inkscape software and add the extension as per below.

To understand the complete process of G-code generation I request you to watch the below video.
If you further have any issue you are welcome in comment section.
Only you have to note that you have to download inkscape 0.48.5 version only

NOTE:- if you arduino get disconnected or reset when machine is just about to start un-check to below option while exporting G-code

NOTE:- If your machine is plotting only some half part of drawing so you can use this template of inkscape download this template and open it in inkscape and set you design in dotted frame

GCTRL

At this point our machine is ready to plot anything just waiting for command,
We also have generated G-code but how to send this G-code to machine?

for this job We are using GCTRL a G-code sender GUI for processing.
We are streaming G-code to machine with the help of processing and GCTRL
Hope you have downloaded GCTRL from above if not download it from here

Simple open the GCTRL.pde by double clicking on it
Now click on play button visible on the top right corner of processing window,
this type of window will appears

All the details regarding how to use this GUI is clearly written there itself.
By pressing the key “p” you can select the COM port from the drop down list.
after selecting the port you can jog X & Y axis with the help of arrow key.
use numerical key “5” & “2” to jog pen up and down.
To send G-code to arduino press key “g” and select the G-code file from the brows window as soon you select the fill and hit enter machine start to plot the drawing.

In this way the process of making Arduio based Mini CNC plotter machine is competed hope I have covered major points if you need to ask any question just simply comment in the comment section below. I’ll try my best to answer you.