Arduino Projects > Polargraph

Finished Polargraph

The working polargraph powered by an Arduino Uno and a motor shield.

Working polargraph

Working

March 18, 2013: I just happened to have almost everything I needed on hand to make this project and I have been fascinated by the drawing bots that have been popping up all over the internet...

You are going to need a few things for this project. First, you are going to need to have an Arduino or suitable clone and a motorshield. I have an Arduino Uno and a Motor shield purchased from Adafruit Industries. You can find all sorts of clones out there, but I would recommend getting your parts from a reputable dealer. Other things you will need include:

Two steppers, a servo,  a piece of board (I would not recommend smaller than 2' x 2'), string (I used fishing line), wire, bobbins, small piece of 1" PCV pipe, bolts or thumbscrews, a CD porotective blank (no shiny bits on it, so you can see it drawing), header pins (not absoultely necessary), and a 3 pin female connector for the servo.

One of the trickiest bits was figuring out the wiring for the steppers. My steppers have six wires or unipolar steppers. If you cannot locate a wiring diagram, the easiest way to figure the stepper out is to ohm the wires systematically. The data plate on my steppers says that the resistance of the motor is 26.5 ohms. So, when I find a pair of wires with roughly double that, I have found a coil. For example, my stepper has red, black, blue, yellow, white, and green wires. If I ohm across red to black and get 26 ohms, one of the wires is the ground for the coil. I ohm from red to blue and get 52 ohms. Ah HA! I found my first coil (red-blue) and one of the grounds (black). You can find a really good tutorial on unipolar steppers here.

I downloaded the software for the project from Polargraph.co.uk. He also sell kits with a custom Arduino shield. So, if you want to buy one, check out his site here. There is also an excellent instructable for the Polargraph. I referred to it extensivley while I was configuring it.

If you look closely, you will see that my drawings are a bit skewed. This is due to a couple of things. I suspect that the bobbins are slipping. And I cannot stress enough the measuring your machine. This made the biggest difference in my drawings.

If you have any questions about this project, email me.

Stepper Wire

This is the wire I used for the steppers and the servo. I had to add one wire for ther steppers and take one out for the servo. I got this wire a couple of years ago from RadioShack. They sell it as 20 foot spool of 24AWG 4 solid conductor intercom wire.


Arduino Motor Shield

Here is a shot of the Adafruit Motor Shield working. Note the white card under the board. I did that to prevent the board from shorting out on the Arduino.

Closeup of mounted stepper


This is a close up of the mounted stepper. As you can see it is an Applied Motions Product, 205461 REV. A. It runs at 8.56V and 0.323A. I am using a 9V WallWart rated at 1A to power the steppers.

Closeup of bobbin


I cut the hole big enough for the bobbin to fit through. It is a standard sewing machine bobbin. Fortunately my wife sews, so she had a few spares on hand. I had some tape on the stepper shafts so I could monitor movement easier. This allowed for me to press fit the bobbins on the shaft. The mark on the bobbin was to measure how much line when out with one revolution.

Gondola

Here is a closeup of the pen gondola. I added the washer and nuts for added weight. I also added an extension to the servo arm to better lift the pen assembly. There is also two short pieces of dowel towards the top of the CD blank which aids in lifting the pen.

Close up of pen tip

This is the bottom view of the gondola. You can see that the pen is just off of the page in the pen up position.

Drawing

Drawing a picture.

 

 dog

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Mona Lisa

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David - scribble

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David - variable square

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pattern

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