How to Build a Tiny CNC Drawing Robot

Posted on November 20, 2013 by MakerBlock

Tiny CNC – all the parts needed

UPDATE: Here’s everything you need to to build a Tiny 3-Axis CNC robot using just 8 plastic pieces.

The above are nearly all the tools and parts you’ll need to build your own itty bitty CNC drawing robot.1 If you have a 3D printer and a spare Arduino, the rest of the parts should cost you around $20. Right now this robot only has two axes, but in the very near future I hope to add either a Z axis or a pen lift. Without further ado the tools needed are:

Tools

One small precision screwdriver

Parts

2x Micro Servo Motors
6x 3D printed parts, downloaded from Thingiverse
1x rubber band
1x pencil

You’ll also need an Arduino, some wire to connect your servos to the Arduino, and a USB cable to communicate with the Arduino.

Assembly

Step 1: Print parts

All printed parts

There are only six printed parts necessary for this mini-CNC. If you’re careful, you’ll be able to fit all six on your MakerBot Replicator into a single build plate.

Step 2: Assemble the X axis stage

Grab your Micro Servo, the little screw that came with it, the flat gear (really, pinion), and the X axis stage. Just insert the Micro Servo into the X axis stage (it only fits one way), push the gear onto the Micro Servo’s motor shaft, and use the screw to secure the gear. It should look like this when done:

Assembled X axis stage

Step 3: Place the X axis stage on the large X axis rack

X axis stage and X axis rack

With the X axis stage gear-side down, rotate the gear clockwise until it stops.

X axis stage and X axis rack

Then place the gear into the X axis rack as show.

Step 4: Place the Y axis rack

Y axis rack

Locate the Y axis rack and place it over the X axis Servo Motor.

Y axis rack in place

Like so.

Step 5: Assemble the Y axis stage

Building the Y axis stage

Just as with the X axis, gather the parts and assemble. This time, the servo motor goes into the stage (it only fits one way), the thick gear is then pushed onto the motor shaft with the gears toward the Y axis stage.

Assembled Y axis stage

Like so.

Step 6: Add the Y axis stage

With the Y axis stage gear-side down, rotate the gear clockwise until it stops.

Getting the Y axis stage ready

Route the X axis servo motor wires through the rectangular hole in the Y axis stage.

Routing X axis servo motor wires through the Y axis stage

Place the Y axis stage down, with the large rectangular hole around the X axis motor.

Almost done building a robot!

Almost done!

Step 7: Ready the pen holder

Place the rubber band around the pen holder as shown. You will probably have to wrap it around a few times.

Rubber band wrapped pen holder

Insert a pencil, pointy-bit down, into the pen holder.

Full assembled drawing robot

Step 8: Admire your work

A baby robot is born!

Your robot is done!

Step 9: Wire Robot to Arduino

To save you a little bit of trouble reading the Arduino sketch and figuring it out, here’s how you would connect your robot to the Arduino:

Use a piece of wire to connect the orange wire from the bottom X axis servo to pin 13 on the Arduino
Use a piece of wire to connect the orange wire from the top Y axis servo to pin 12 on the Arduino
Connect the brown wires from the servos to the ground pins on the Arduino
Connect the red wires from the servos to the 5v pin on the Arduino

Step 10: Draw!

Download my Arduino sketch to operate this robot. The movements of the robot are hardcoded at the moment, so please check back for updates. Also, if you don’t tape or glue or somehow affix the little bot to a heavy surface, it will literally jerk itself all around the table. (Although, in retrospect, I could have made it draw slower…)

It’s a little difficult to see the lines as the robot is drawing, but it really is drawing a grid in this short video:

Room for Improvement

I hacked this little project together just in time for the MAKE and GE Robot Hacks presentation on 11/20/2013, so I know there’s lots of room for improvement. Here are some things I’m working on:

An entire Z axis or pen lift mechanism using a third servo
A better pen/pencil holder
Actual code to use XY coordinates instead of directly specifying the degrees for each servo
Actual motion control software from Processing or Python
A few adjustments to the Y axis stage for a better fit
Possibly thicker gears so that I can use set screws
A variation on the gears to use less plastic
Getting the robot to work with my Adafruit Trinket!

I hope you enjoyed this quick to print and easy to use desktop drawing CNC!

Tiny CNC Drawing Robot

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You’ll also need an Arduino and some bits of wire [↩]

37 thoughts on “How to Build a Tiny CNC Drawing Robot”

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Stan Wawrzyniak on November 21, 2013 at 1:37 pm said:

I’d like to see version 2.0.
- MakerBlock on November 21, 2013 at 1:45 pm said:
  
  @Stan: In that case, check back in a few days! Better yet, join my mailing list ( http://shor.tw/x6 ) and I’ll let you know when it’s ready…
  - keesj on November 22, 2013 at 12:34 am said:
    
    Hi,
    
    Is this a mailing list or a new letter? When I try to register it looks like a news letter. I am interested in the project as I have been trying to make cheap printers/plotters for a while.
    
    Your design looks very elegant. I have been following a slightly different approach by also using lego blocks but this is a really a nice project.
    - MakerBlock on November 22, 2013 at 1:24 am said:
      
      @keesj: I’m honestly not sure about the difference. You sign up, leave your email address, and I email people once in a while with updates – on average probably once a month. Lately it’s been a little more as I’ve been extra inspired. 🙂
      - Jelle on November 23, 2013 at 1:21 am said:
        
        The difference between a mailing list and a news letter is that the latter is one way only, and a mailing list is like a forum over email, where every subscriber can participate.
      - MakerBlock on November 23, 2013 at 9:28 am said:
        
        @Jelle: Ah! Okay, then it is newsletter. 🙂
GeekDoc on November 22, 2013 at 2:04 pm said:

Definitely going to make one of these!

Quick upgrade:
1. Remove pencil
2. Replace with roller-ball or felt-tip pen
3. Upgraded visibility of drawing!
- MakerBlock on November 22, 2013 at 6:35 pm said:
  
  @GeekDoc: Well, then, you should have checked out this post! http://plotterbot.com/2013/11/better-video-of-tiny-cnc-drawing-robot-actually-drawing/
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Chris the Carpenter on November 25, 2013 at 5:09 pm said:

For the love of God, can we please hold our cameras sideways?
- MakerBlock on November 25, 2013 at 6:40 pm said:
  
  @Chris: I was holding it sideways… it’s just that I was born with my head attached 90 degrees to my neck…
Fabsterdam on November 27, 2013 at 9:50 am said:

What a nice little project! We´re printing it now but we discovered that not all micro servos are created equal: ours don’t fit (Modelcraft MC-1811)! The axle is not centered in the X/Y axis stage and it sits too deep. What is the brand/type/model/part number of the micro servos you are using?
- MakerBlock on November 27, 2013 at 11:03 am said:
  
  @Fabsterdam: Oh no! I know that there’s an error in the Y stage STL which causes the motor to sit slightly too deep. This is already fixed in a version I’m part way done on. I’m using micro servos named, “Batan B2122” but I think these from Adafruit would probably work.
  - Andrico on December 22, 2013 at 1:24 pm said:
    
    Would these work?
    
    http://www.amazon.co.uk/gp/aw/d/B00DAN8XI0/ref=mp_s_a_1_1?qid=1387747316&sr=8-1&pi=SL75
    - MakerBlock on December 22, 2013 at 1:46 pm said:
      
      @Andrico: Maybe! I know others have used my designs with those exact motors for a working robot. Even if it’s a loose fit, you should be able to make it work with a little bit of hot glue.
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Ian Campbell on November 29, 2013 at 10:23 pm said:

Um, where is the arduino sketch. The above link just leads you to the thingiverse page. I’ve printed it out, it needs a brain! Thanks.
- MakerBlock on November 29, 2013 at 10:33 pm said:
  
  @Ian: I uploaded it to the Thingiverse page too!
  - Haiyan on December 7, 2013 at 2:59 am said:
    
    I can’t find the arduino code either. Even on the thingiverse page? Can you provide link?
    - MakerBlock on December 7, 2013 at 8:07 am said:
      
      @Haiyan: It’s still there on the Thingiverse page with the printable files! Click “Download This Thing!” and then the file named “MiniCNC003.ino” or “Download All Files”
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Erik on January 11, 2014 at 5:10 am said:

First off, this is a brilliant project! Thanks for sharing it. I have an 11 grade student who is really into it, has printed out the 3-axis plotter and I’ve just gotten the motors for her to put it together. She plans to make a button controller to draw with it.
Second, I want to give a rundown on what worked and such:
*Printing all parts of the 3-axis plotter in PLA was successful. Worked on the first print.
*I ordered the micros from Adafruit you mentioned above, http://www.adafruit.com/products/169, they fit perfectly.
*I assembled the pieces myself with the motors and found only one slight problem. In step 4 where you “pressure fit the Y motor mount onto the X axis” I had to do some filing before it would begin to fit. It’s very tight. I guess that’s important to hold it in place, but you might want to suggest having a file on hand.
Again, excellent project!!!
- MakerBlock on January 11, 2014 at 2:29 pm said:
  
  @Erik,
  Thank you! I’m glad to hear you guys were able to get yours working. I love the idea of making a button controller for this robot. Doing so means it could be operated without the need of a computer. I was thinking about using my Makey Makey, with its integrated “directional keypad” to directly control the robot.
  I’m particularly glad to hear your parts came out well in PLA. I’ve only printed my versions in ABS to date.
  I actually designed this robot and the motor mounts with Adafruit’s analog micro servos (totally overkill for this project – but they’re what I had on hand) which probably explains why your parts needed a little extra sanding/filing. With the next version of these parts and the associated assembly guide, I will be sure to include a mention of sandpaper/file. 🙂
  Please send me a picture or upload one to the Thingiverse page – I’d love to brag about your success!
  - Erik on January 11, 2014 at 3:19 pm said:
    
    @MakerBlock, it turned out the Z axis pinion needed sanding the diameter down almost to the gear teeth to get the Z rack to fit without pushing the Z pinion and servo away at a tilt. I can’t see how you got yours to fit without doing that. I will definitely upload a picture, it looks awesome. Just still working on attaching a pencil securely. Also, this is an awkward place to post code, but this Arduino sketch is a quick way to determine your min and max positions for each servo people might find useful. It does not use a motor shield, just the standard Servo library:
    
    //Just for testing initial servo positions of 3-axis plotter by @MakerBlock
    #include
    
    Servo myservoX;
    Servo myservoY;
    Servo myservoZ;
    int posX = 180; //X = 180, in position (not out)
    int posY = 0; //Y = 0, right position seen from behind
    int posZ = 0; //Z = 0, up position
    
    void setup()
    {
    myservoX.attach(3); // servo on PINOUT 3
    myservoY.attach(4); // servo on PINOUT 4
    myservoZ.attach(5); //servo on PINOUT 5
    //init positions
    myservoX.write(posX);
    myservoY.write(posY);
    myservoZ.write(posZ);
    }
    
    void loop() {
    //do nothing
    }
    - MakerBlock on January 11, 2014 at 4:02 pm said:
      
      @Erik: Oh, yeah, I need to revise that Z pinion. There’s a small error in the code that causes the flange to be too wide. I just forced it together on my robot and it just works. If your code doesn’t show up well in the comments section, I’ll post it in the blog. Have you tried the code I posted on Github? It should let you operate your drawing robot ready to draw SVG files.
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Jeff Herrick on October 7, 2014 at 8:00 am said:

Just saw your mini CNC project….love it!
I’m a Mentalist looking to build a new illusion using this technology. How much smaller can this get?

Jeff
Sonyika on December 15, 2014 at 8:30 am said:

Hi!
Thank you for the tutorial!
I haven’t got 3d printer… but if anybody tell me how size the parts I can make it.
Thank you very much!
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Rusty on January 16, 2016 at 4:56 pm said:

This is awesome – did you ever finish the z-axis upgrade and post it as well?
- MakerBlock on January 16, 2016 at 5:32 pm said:
  
  @Rusty: I did finish the Z axis upgrade and posted it!
Anna on June 1, 2016 at 1:55 pm said:

Thank you! I’m looking for a way of creating a hand-operated pretend-CNC machine to help my students understand what the CNC Plasma table is doing. This has helped me figure out some of the parts that I can create to make that happen. Thank you!

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