In this project I'm showing you step by step how to build a low cost Arduino based mini CNC ink plotter machine using a scrap DVD player's stepper motors , Arduino NANO, and also I will show you how to make a circuit/driver for stepper motors. The maximum printing area of this CNC machine is (40*40mm). You can use this machine for drawing labels, symbols etc., this CNC machine is requires only 5V, 1A of power for the working.

Supplies

Arduino Nano/UNO
Two scrap DVD players
Servo Motor
L293D IC *2
Screw terminals * 5
Female/male header pins
Zero PCB board
90 degree aluminum angle
Plywood sheet
PVC or acrylic sheet
Nut bolts
5v,1amp adapter

Step 1: Deassembly of DVD Drives and Identifying Pins of Stepper Motor

Open the scrap DVD drive and taking out the stepper motor and its rail.
After that the important step is identifying the terminals or Coils of stepper motor, for that take a multimeter and set it to the continuity mode.
Generally the motor used in DVD drives have 4 terminals i.e. set of two coils. To find out terminals of each coil, touch the probes of multimeter with each terminals and check the continuity .

Step 2: Making Arrangement for X,Y,Z Axis

X-axis:-For the arrangement of X-axis I used 90degree aluminum angles and shaped it like "|_|". Bottom angle is used to secure it on 15mm thick plywood with the help of two nut and bolt. And vertical two bars are used to secure the stepper motor and its rail using 4 extended nut bolts. The width of bottom aluminum angle is(132mm) & height of two vertical angles is(150mm).

Y-axis:- For this arrangement I simply attach the stepper motor and its rail of plywood with the help of 4 extended nut bolts.

Note:- Set the position of both X and Y axis motor at the "ZERO".

Z-axis:- Making Z axis or pen assembly is quit difficult. I used PVC sheet to make the overall Z axis structure because it is light in weight and PVC sheets are cheaper in cost than that of acrylic sheets. In this pen assembly we have to make arrangement so that the pen can move UP and DOWN. To drive this assembly I used servo motor. Also I added two springs with guide so that it gives better stability to the pen when it is at down position or while writing/drawing.

Step 3: Double Sheet Assembly for Y Axis

The surface of CNC machine must be plane or aligned 90 degree with the X axis, if it will not then it doesn't create proper drawings. For the mini CNC machine it is not value for money to use Auto-level/ aligned hardware; so that I make a simple arrangement and with the help of it we can aligned the Y-axis surface manually.

I stuck the (80*80mm) PVC sheet to the Y-axis rail with the help of adhesive and drill the (2.5mm) holes at the corners.
Then put the 4 extended (2.5mm) bolts in holes and fix it with their respective nuts. Then insert another 4 nuts in each bolts at specific height of bolt.
After that I cut another (80*80mm)PVC/Acrylic sheet and drill at its corner with same drill diameter. Then this sheet is inserted at the top of previous PVC sheet with matching their 4 bolts and secure with another 4 nuts.

By adjusting the position of nuts we can adjust the alignment of Y axis surface with respect to X-axis.

Step 4: Driver Circuit for Stepper Motors

As servo motor is built in with driver circuit so that we can directly connect it with arduino, but in case of stepper motor it cannot come up with driver circuit so that it is essential to make circuit externally and connect it with stepper motor.

In a market their are no. of driver circuits are available but their cost are high and we are using small stepper motor so that instead of buying we can make a simple driver circuit for mini CNC or mini stepper motor.

As the motors used is DVD drives requires 5volt,1amps of power for their proper working so that I choose a L293D H bridge IC which can operates from 4.5 to 36 volts with peak current of 2amps per channel. I used pair of two IC which drives the X and Y axis motor.

Arduino is used to give logical input to the input terminals of IC.

I attach the Schematic diagram of driver circuit and also added the PCB layout (Bottom layer , Top Silk layer)

Step 5: Testing of Stepper Motor and Its Driver

Before making an arrangement of X and Y axis we must test the both motor. After pin identification and Completion of Driver circuit connect the stepper motor with driver and upload a step_perrevolution(Arduino code)to check/run motor.

I uploaded a testing video of stepper motor.

Step 6: Software Setup for Mini CNC Ink Plotter Machine

I uploaded the video of software setup in that I'm showing you how to upload arduino code then how to create a G-code for TEXT and for DRAWINGS in INKSCAPE and also showing how to add the G-code file in PROCESSING software to run CNC machine.

Arduino IDE download link :-https://en.softonic.com/download/arduino-ide/windows/post-download

Arduino USB driver :-https://www.srishtirobotics.com/more/blog/154-arduino-uno-r3-clone-ch340-ch341-usb-driver

INKSCAPE 0.48.5 :- https://inkscape.org/release/0.48.5/windows/

MakerBot Unicorn G-Code Output for Inkscape :-https://github.com/martymcguire/inkscape-unicorn

Processing Software :- https://processing.org/download/