In this project I will show you how to easily build your own low-cost Arduino Mini CNC Plotter!
This project is an update from my previous cnc, with better construction and with more accuracy.
I decided to make this detailed guide to help you make it on a few easy steps.
For the X and Y axes we will use two stepper motors and rails from dvd/cd drives and for the Z axis we will use a small servo motor that moves the pen up and down. For the mounting base we will use a small piece of plexiglass.
You can easily attach a pen (or pencil) - irrespective of its thickness - on it.
The Arduino-based circuit is using the ATmega328 microcontroller, two L293 motor driver ICs and an usb to serial module. You can easily make it with the Arduino uno board and an breadboard.
You can also use an Bluetooth module (e.g. HC-06) to print your texts (or images) wirelessly through your computer Bluetooth connection! Pretty cool huh?
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- ATmega328p (with Arduino Bootloader)*
- 28 pin DIP IC Socket
- 16MHz Crystal Oscillator
- 2x 22pF and 1x 100nF capacitors
- 10K resistor
- USB to Serial adapter**
- 2x L293D ICs
- Mini Servo Motor
- 2x DVD/CD Drives
- Prototyping PCB Circuit Board Stripboard
- 4x 2pins Screw Terminal Connector (or 2x 4 pins Screw Terminal Connector)***
**USB to Serial adapter will allow the circuit to communicate with the computer through the USB cable, just like Arduino uno does.
***Why to use screw terminal connectors? Because you don't want to solder and desolder cables from stepper motors until you find the correct working combination!
For the mounting base:
- One piece of plexiglass 20x16 cm (thickness 5mm) (for X axis)
- Two pieces of plexiglass 14x4 cm (thickness 5mm) (for Y axis)
- A few nut screws, nuts and shims (~20)
- A few spacers
- Four supporting angles (preferably plastic)
- Soldering iron
- Cutting tool (e.g. Dremel) (Optional for cutting plastic/plexiglass parts)
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In my case, one of stepper motors uses the first and third cable for first phase-motor and the second and forth cable for second phase-motor.
Find the correct combination and proceed to next step.
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Mounting base, X , Y and Z axes
For X axis:
Place one stepper motor (with rails) on a big plexiglass piece and mark it with a pen in order to open the (4) holes for the screws. Make sure that is perfectly align! (use a triangle ruler). Open the holes and mount the motor with nut screws.
Place on one side of it the four mounting angles and then mark it with a pen in order to open the (8) holes required for the screws. Make sure that the distance between them is 5mm (thickness of plexiglass). The second image above will help you to understand more.
For Y axis:
Place the other stepper motor on two plexiglass pieces and mark them with a pen in order to open the (4) holes for the screws. Again, make sure that the motor is perfectly align (use a triangle ruler).
Place the two pieces of plexiglass on the X axis (big plexiglass piece) and mark them with a pen in order to open the (4) holes required to fit on the mounting angles.
Complete the construction:
Open all holes and complete the construction (see the 3rd and 4th image above). As you can see I placed a metal surface on X axis to fit a note-paper sheet on it. A note-paper sheet usually has dimensions 75mm x 75mm, but remember that printing area is only 40mm x 40mm. Remember, all parts must be perfectly align with others, this is very important!
For Z axis:
That's the most difficult part of our construction.
You will need something to attach it on X axis, a flat surface. On that surface you will attach the servo motor (Z axis) and the pen base. Pen (or pencil) must be able to move up and down with the help of servo motor. Watch the above image to understand what you need to do to duild Z axis.
Tip! Use your imagination ;)
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Now that we have our contraction ready, it's time to build the circuit and test the stepper motors (X and Y axis). Watch the above image with breadboard circuit schematic.
Steppers motors wiring is something that need patient. On the next step you will find a 'testing' code for x and y axes. If a stepper doesn't work properly you must find the correct working combination by changing the cables between them and the L293D ICs.
You will need more current than one usb port can give, so you must connect one more usb cable, see the 2nd image above. Connect only power cables (usually red and black) with the primary one. The voltage remains 5V, but you have doubled the current! (from wiki: max. current of USB 2.0: 0.5 A and of USB 3.0 & 3.1: 0.9 A).
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Testing the X and Y axis movement
Codebender is an online Arduino IDE - It's the easiest way to program your Arduino board directly from your browser! Just click on the "Run on Arduino" button and that's it! Try it! It's really amazing!
For X axis
For Y axis
The CNC Code
Here's the main CNC code, embedded using Codebender!
In this part you will see your pen goes up. If don't, change penUp and penDown variables that controlling the servo motor.
Press the "Run on Arduino" button and program your board from your browser!
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The GCTRL program
What is gcode?
Gcode is a file with X,Y and Z coordinates. Header of this file is set to:
M300 S30.00 (Servo down)
G1 X10.00 Y10.00 F2500.00
G1 X20.00 Y10.00 F2500.00
M300 S50.00 (Servo up)
Download Processing from here, now donwload and open GCTRL.pde application.
- Click the "play" icon/button to start the program.
- Now press 'p' and select your Arduino serial port.
- Press 'g' and select the 'drawing.gcode' file
(If something goes wrong, press 'x' to stop the plotter)
Make your own gcode files!
Inkscape is professional quality vector graphics software which runs on Windows, Mac OS X and Linux. It is used by design professionals and hobbyists worldwide, for creating a wide variety of graphics such as illustrations, icons, logos, diagrams, maps and web graphics. Inkscape uses the W3C open standard SVG (Scalable Vector Graphics) as its native format, and is free and open-source software.
Download and install Inkscape from here (Important: download 0.48.5 version)
Now you need to install an Add-on that enables the export images to gcode files. This add on can be found here with installation notes.
Setup Inkscape for first use
Open the Inkscape, go to File menu and click "Document Properties". See the 1st image above and make the changes, make sure to change first to "cm". Now close this window. We will use the area within 4 to 8 cm. See the 2nd image above.
How to print text:
if you want you can change font and size. Now click on cursor icon and center the text like the 3rd image above. Select Path from menu and "Object to Path".
How to print image:
This is more difficult than texts. Images must have a transparent background. Drag and drop your image in Inkscape. Click ok to the next window. Now you have to re-size the image to fit the printing area, see the 4th image above. Click Path from menu and "Trace Bitmap". Make changes as the 5th image above. Click ok and close the window. Now, move the gray scale image, and delete the color one behind it. Move the grey image to the correct place again and click from Path menu "Object to path". The 6th image above show how to delete image outline.
Export as gcode
Final, go to file menu, click save as and select .gcode. Click ok on next window. That's it! Ready to go! Use the gctrl.pde app to print the gcode file on your new Arduino CNC Plotter!
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