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Polargraph Drawing Machineby Euphy on November 9, 2011

Table of Contents

Polargraph Drawing Machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Intro:   Polargraph Drawing Machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Step 1:   History . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Step 2:   Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Step 3:   Sprocket up! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

File Downloads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Step 4:   Prepare your motors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Step 5:   The drawing surface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Step 6:   Mount your motors - edge style . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Step 7:   Mount your motors - front style . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

File Downloads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Step 8:   Electronics - Arduino . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

File Downloads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Step 9:   Electronics - Motorshield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Step 10:   Electronics - Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Step 11:   Controller software - install . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Step 12:   Controller software - Primer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Step 13:   Controller software - serial port configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Step 14:   Controller software - make it move! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Step 15:   Assemble the gondola . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

File Downloads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Step 16:   Add cord and counterweights . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Step 17:   Back to the drawing board . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Step 18:   Finish configuring your controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Step 19:   Upload your measurements to the machine . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Step 20:   Now really make it move! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Step 21:   Choose what to draw . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Step 22:   Choose a pixel style . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Step 23:   Load it up and get scribbling! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Step 24:   Pen lift servo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Step 25:   Pen thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Comments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

http://www.instructables.com/id/Polargraph-Drawing-Machine/

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Author:Euphy    author's websiteI like making things. I'm currently a computer programmer by trade, which I adore, but I like building physical things when I can. I like pottery and lino cuttingand photography, and I love the seaside, and the smell of hot solder. I have a few years of formal design training and design a small range of 3D printedjewellery.

Intro:  Polargraph Drawing MachineThis machine, a variation on the hanging-pen plotter is a conspicuous and wilfully naive attempt to break out of the pristine, pixel perfect, colour-corrected space thatexists inside our computers. It's a drawing machine, that takes a pen (a human tool) and uses it to draw in a singularly robotic way, with some grand results.

It doesn't draw at all like we would (though it could), and we would struggle to draw exactly as it does (though we could).

It can draw on things bigger than itself - the question is really "how long is a piece of string?" when it comes to working out it's maximum area.

It's easier to look at what it does, than to explain it, so just have a look.

Step 1: HistoryWell there have been lots of new drawing machines doing the rounds lately, there's a real thirst to see devices that leap out of the virtual into thephysical. For me, it's all too easy to produce digital things which are interesting - programming or mash-ups or virtual experiments are devalued because they areintangible, you can run a hundred, a thousand, a million variations in a day - it's the proverbial roomful of monkeys with typewriters. The output becomes disposable, itget's hard to see the value, the craft.

So 3D printers and other desktop manufacturing tools and technologies (laser cutters etc) have got more and more popular, it's hard to overestimate how much hungerthere is for a tangible, physical, touchable, smellable product of all this clever-clever digital work.

So this isn't wholly original, check out this prior art for more inspiration:

Hektor - the daddy of all hanging drawing machinesDer Kritzler - the smartest one yetAS220 Drawbot - the basis for mineSADBot - automatic drawing ible

Or have a look at what I've been doing with minePolargraph website

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Polargraph project code and wikiFlickr stuff

Step 2: PartsThere's a hundred different ways of making a machine like this, but I'm going to show you how I make mine, as a jumping off point. I hope you'll see some places it canbe improved.

Electronics.

Microcontroller - Arduino (ATMEGA328) compatible. I've used a Seeeduino here. (from coolcomponents).Motor drivers - Adafruit's Motoshield. A modern classic. It can drive two stepper motors each drawing up to 600mA and has pinouts for a servo too, so is perfectfor this project. (oomlout.co.uk)Motors - 400 steps per revolution (0.9 degree per step), 4.6v NEMA 16 stepper motors. These have a 5mm diameter shaft. (ebay - astroyn excess).Power supply. 1 amp (1000mA) Variable voltage AC/DC power supply. I set mine at 6v. At peak, the machine might be drawing 1.2 amps (2x 600mA), so youmight benefit from a beefier-than-average power supply. That said, it ran for months on a 600mA supply before I did something silly and it stopped. (expro.)

Gondola. This is the pen holder. I am from the "heavy and stable" school of thought. I think it makes for a more definitive impression, and a cleaner line.

3x 6003Z deep groove bearings. (simplybearings.co.uk)50mm length of K&S stock #144 brass tubing (21/32", 16.66mm dia). (hobbies)Laser cut acrylic parts. The original is made of corrugated cardboard and a blank CD, just glued on, so this is by no means necessary. (Ponoko)

Running gear.

Beaded cord. This is used in roller blinds. (ebay - a shade better). You could use metal ball chain if it matches the pitch.Sprockets. Don't seem to exist off-the-shelf, so I made these 3D printed ones (shapeways).Counterweights. I used a bolt with a stack of washers hung on it.

Hardware.

Surface - big flat surface to base your machine on. Discussed in the next step.Brackets - laser cut plywood to allow the motors to be fastened to a flat wall. If you are mounting on a board, you might be able to just simply stick the motorsdirectly on the top edge of the board. (Ponoko)

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Step 3: Sprocket up!I couldn't find a source for these beaded cord sprockets. Roller blind mechanisms have them in, but not in an easily usable form. I made my own and had them printedthrough Shapeways . John Abella has made a parametric sprocket suitable for other bead spacings that can be 3d printed at home if you have access to something like amakerbot or a reprap.

Push-fit a sprocket onto the 5mm shaft of the motor.

File Downloads

sprocket trispoke wide 5mm axle thick walls double with sprue.STL (1 MB)[NOTE: When saving, if you see .tmp as the file ext, rename it to 'sprocket trispoke wide 5mm axle thick walls double with sprue.STL']

Step 4: Prepare your motorsStrip the ends of the motor wires and tin them. Unless you have very long wires already on them, you'll be extending them, and use whatever is to hand to do it - in mycase, I used plain screw terminals. Make sure you label your extension cable too.

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Step 5: The drawing surfaceFind a big board or something to use as your surface. Your board should be at least 150mm bigger on each side than the largest sheet of paper you want to draw on.

You can use a wall if you have some motor mounting brackets, but I was always terrified about it going wrong and scrawling marker pen over my wall. My landlady wouldbe unimpressed, I feel.

Using a board means you can tilt it slightly too just by leaning it against the wall, and that's a good thing because the weight of the gondola presses the pen to the page.When the surface is perfectly vertical, it's hard to get any pressure against the page - the lines tend to come out a pretty woolly.

I went down the local DIY shed and scavenged in the offcuts bin for the biggest bit of chipboard I could fit in my little car, but I've also had good success with building amachine based on the biggest IKEA Ribba picture frame. This has the added feature that you can use it as a picture frame afterwards, amazingly. A whiteboard is a goodalternative too, because you can test quickly, but any kind of flat surface will do. My first one was only big enough for A3, and worked fine, so don't feel it has to bemassive.

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Step 6: Mount your motors - edge styleYour motors should be mounted so that the sprockets are as close as possible to the drawing surface. If you have a thick surface, you can get away with just sticking yourmotors to the top edge of the board with double-sided foam tape. This is actually a nice way of doing it because it cushions the vibration too. The motors do tend to twist abit, because their little foam rafts have some stretch in them, but on mine it wasn't really a problem unless I left the gondola hanging for days.

This arrangement is much neater when it comes to cabling and things too. It all hangs down the back.

If you have access to a 3d printer, there is a neat stepper motor mount available at http://softsolder.com/2011/08/23/nema-17-stepper-motor-mount/.

Step 7: Mount your motors - front styleThis is way I've come to mount the motors, and it looks a bit untidy, but it is less dependant on the type of your drawing surface - it can be stuck onto anything basically,including walls and other enormous surfaces.

I have attached plans for a motor mount to be lasercut from 3mm thick plywood, but there's nothing clever about it except that it only slots together, so the motory bits canbe removed easily, leaving the main mount plates in place. I have got it on a Ponoko P1 sized piece of board, and you will need two of these cut.

The plans for Der Kritzler include window-mountable servo holders that use suction cups. That bracket is probably stronger than mine too, but it needs more parts to buildit.

Fasten the big plates onto your surface in the top corners. They should be exactly level. I use double sided sticky foam tape for more or less everything, but make sureyou use plenty because they are fairly heavy, and there is some vibration.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

http://www.instructables.com/id/Polargraph-Drawing-Machine/

File Downloads

flat mount parts2 p1 2011.11.13.eps (981 KB)[NOTE: When saving, if you see .tmp as the file ext, rename it to 'flat mount parts2 p1 2011.11.13.eps']

Step 8: Electronics - ArduinoYou need an ATMEGA328-based arduino compatible board, I used a Seeeduino v2.21 here - it does the job very nicely.

Upload the polargraph_server code to the arduino. Look at this fine guide courtesy of Adafruit for help.

The code is attached to this step, but the very most recent version can be downloaded from the polargraph code repository .

Once you do that, you should confirm that it is working properly - use the serial monitor on the board to make sure that it is issuing "READY" every couple of seconds.

File Downloads

polargraph_server.pde (48 KB)[NOTE: When saving, if you see .tmp as the file ext, rename it to 'polargraph_server.pde']

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 9: Electronics - MotorshieldThe motorshield is usually supplied as a kit, it's easy to solder up, follow the instructions on the Adafruit site. It's brilliant. I am an Adafruit fanboy, so sue me. Not muchmore to say about it.

The motorshield has two stepper motor ports, one on either side. It takes it's power from the host arduino, but has an separate connector that you can use to connect anexternal power supply. If you have a power supply that has bare leads, you can screw them in here (make sure you get the polarity right) use this and remove the powerjumper from beside it. I'm going to stress that the power connector is wires up properly - +V on the left hand wire, GND on the right. There is no reverse polarity protectionon this board, so if you do it wrong it's likely you'll damage the board, and maybe your arduino too.

If you don't use it, you should plug your external power supply directly into your arduino, and leave the power jumper ON. I am wiring directly, because it's better practiceto have entirely separate supplies for motor and logic, and also because the Seeeduinos have a funky JST power connector on them that doesn't fit anything standard.

I also added little heat sinks to the driver chips (L293Ds) on the motorshield. They get hot, and you can use a fan to cool them if you have one spare, and really, I don'tknow if they every really get dangerous, but with heatsinks on I feel a more comfortable letting them run for hours and hours.

Step 10: Electronics - WiringEach motor has two circuits, or coils in it, and a bipolar stepper has four wires coming out of it, two for each circuit. Most steppers will have a datasheet that will let youknow which colour wires lead to which coil. Find out, either using your datasheet, or a multimeter (a bit more about steppers, and how to figure them out on adafruit andthis article helped me figure it all out.).

Mine have the red and the blue wire attached to one coil, and the white and the yellow wire on the other coil.

The two motors should be wired up with their coloured wires matching left and right. So on the left hand side, you should have wire pair 1 (red/blue) in the top twoterminals, and wire pair 2 (yellow/white) in the bottom two terminals. And on the right, it'll be exactly the same: pair 1 in the top, pair 2 in the bottom.

I stuck my arduino to a bit of foamcore board stuck on the back of my drawing surface. Just makes it a bit easier to deal with.

Push the motorshield into the arduino, and fire it up!

http://www.instructables.com/id/Polargraph-Drawing-Machine/

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 11: Controller software - installThe setup is ready to test! The software you use to control it is a little application written in Processing. For this, you should download the Processing developmentenvironment from processing.org . Once you have it installed, you should find your sketch folder on your computer (mine is inside My Documents/Processing on windows7), and create a new folder in it called "polargraphcontroller". Then download this application source code file from the polargraph code repository, and put it inside.

If you're curious about Processing, you're right to be: It's ace. There are useful tutorials on processing.org , and of course here on Instructables too. It's basically java, butoptimised to run little stand alone programs with graphics.

So open Processing up, and go to File->Sketchbook and you should see "polargraphcontroller" listed there. Click on it, and the application should open up. It'll only bevery small, so go ahead and maximise the window, or stretch it so you can see everything. If it worked, then well done, skip ahead a step!

Step 12: Controller software - PrimerOk, basically, on the left hand side of the controller application window, you see a grey box that represents your machine. There's a white and black box in the middle thatis your page, or your piece of paper. As you move your mouse over it, you'll see pink lines showing where the strings will eventually hang.

In the middle-to-right of the window is the button panel. This is all the functions the machine can do. Some are just to do with the controller (like "load image"), but some(like "set home" or "shade square wave") send commands to the machine itself.

If a command is issued to the machine, it's held in a queue until the machine signals to say it's ready to do something. The command queue is shown on the far right ofthe app window. When you first start it up, it's in paused mode. You can start it and stop it by clicking on the queue header (where it says "COMMAND QUEUE: Paused -click to start"). The queue can be emptied with the "reset queue" button.

The interface is separated into four "pages", switch between them using the F1 to F4 keys.

F1 - Input. Used for loading images, moving, resizing, selecting an area to draw, as well as issuing the drawing commands. Click on load image and browse to a1.bitmap (around 500pixels is a good start), then move image to place it centrally.F2 - Density preview. Once you've selected an area, you can see what detail has been extracted on this page. You can use the rowsize up / rowsize down2.buttons to modify your detail level interactively, and use inc sample size and dec sample size to change the contrast on what get's captured.F3 - Details. Upload machine size to the machine, and also save the current controller app settings to a configuration file. Do that now (click save properties).3.F4 - Command Queue. This is just to make the queue more accessible for small screens, but the queue can also be exported to a text file, and imported too. The4.commands are all just plain text, so it's easy to hack them.

You need to do a little configuration before it'll connect to your hardware.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 13: Controller software - serial port configurationMany of the features in the app are setup in the app itself, but the initial configuration is all done by editing the polargraph.properties.txt file that gets created in the sketchfolder the first time the application runs.

The first thing to set up, and in fact, the only thing we'll be setting up right now, is the setting which controls which serial port the machine is connected to.

Close the app, and then restart it again, and then close it. Now look in the console area (the white-on-black area at the bottom of the Processing editor window. Scroll uppast a load of stuff that says "machine row: blah blah" until you get to the part outlined in the image on this step. This is a listing of all the serial ports Processing can see.Your machine will almost always be the second one in the list, but it's actual name will vary a lot. In our case, what we're looking for is the very first number on the line.So, here, it's number 1.

Open up your polargraph.properties.txt, and find the line for the property controller.machine.serialport and change the value to whatever number you arrived at before.I change mine to be controller.machine.serialport=1 . Note that you don't care about the actual name of the serial port, only where is appears in that list.

Now save the file, and restart the app.

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Step 14: Controller software - make it move!Confirm you have set the right serial port, and that it's communicating with the arduino by looking for a READY! in the block of text shown on the left-hand side of thescreen, over the machine. This block can be hidden by pressing the I key if it's getting in the way.

You should also be seeing incoming: READY in the Processing console every couple of seconds, in the background.

That's great! Unpause the command queue, and click Set home . You will see the big purple dot that signals the location of the pen will move to be in the middle of thetop edge of the page preview. The motors themselves will also give a little wriggle, and you'll find they're locked - they're now under power!

Ok, now click the Move pen to point button, which is as close to a manual move command as you have, and click somewhere right down at the bottom of the machine.With luck, you will hear and see the motors whirr into life, accelerate and then decelerate back down again.

The purple spot will move too. This is where the machine thinks the pen is.

Try is again, and make sure the sprockets are moving in the right direction. When the machine is moving the pen down the page, the left-hand motor will be spinningclockwise, and the right-hand motor will be spinning anti-clockwise. When the machine is moving up the page, it'll be the other way around.

If one, or both of your motors are going in the wrong direction, you might have got your datasheet wrong, or made an error when labelling them up or something. You justneed to swap your two pairs of wires around. To be honest, trial and error is as good a way of working out the correct circuits as anything else, but it's hard to do untilyou're absolutely sure all the rest of it is working right.

Good work! I recommend a cup of tea! There's no part of a project quite so rewarding as that first moment when it moves, or makes a noise, or electrocutes you, I thinkyou'll agree.

Step 15: Assemble the gondolaThe gondola is the pen holder. There's a few alternative designs out there for them, including this 3D printable one that seems to do the business nicely. My design ismuch heavier, and has a hollow centre so that the pen can always be in the exact point where the cords converge. In practice, I'm unclear about how much difference thismakes, but it makes me feel good.

I made the first one from corrugated cardboard, and a blank CD, stuck to some ball bearings (see the last picture on this step). Later I graduated onto some fancy-danlaser cut parts (available through ponoko ), but the principle is the same. I've attached the design in an EPS on a ponoko P1 sized board.

The parts just slide together, and then onto a length of brass pipe (see parts list). The laser cut parts have nodes in them that will need a little filing to get them on. Just becareful because the acrylic is pretty brittle. It should all push-fit together, but if it gets too loose, a few dabs of glue will keep it together.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

File Downloads

1x gondola with stabiliser v2 p1 2011.11.13.eps (982 KB)[NOTE: When saving, if you see .tmp as the file ext, rename it to '1x gondola with stabiliser v2 p1 2011.11.13.eps']

Step 16: Add cord and counterweightsThe length of the cord will obviously dictate the size of your drawing. Make your cords long enough to stretch at least from your sprocket to the opposite corner of yourbiggest drawing paper sheet, when it's mounted. Don't forget to leave a couple of inches to tie/clip your counterweights on with. Just push one end into the clips on thegondola.

I use some bolts with washers on them as counterweights, but you can use anything - bags of change are a good alternative. The exact weight isn't critical at all - this isnot a finely balanced machine. The object is to have the gondola hang naturally in the upper-middle of the machine's drawing area. My weights are around 150 gramseach.

After this, you may even wear your gondola with beaded cord as if it is a steampunk arc reactor medallion. I often do, and feel very powerful at it. POW! TAKE THAT,BAD GUYS!

Ahem... Or you can just put it on the machine, draping the cords over the sprockets. You'll need to figure out a neat way of avoiding the cables if you have front-mountedmotors like me.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 17: Back to the drawing boardOk, the last bits of configuration then:

Measure your machine size1.Find your home point2.

Use the diagram attached to this step, and draw lines on your drawing surface in the places marked.

It's important that the lines are all square and parallel, and your measurements are accurate. You can't hope to get good results if you don't have it marked out properly.As they say: Proper Preparation Prevents Poor Polargraphs . Don't they?

Ok, so measure your machine width, in mm. This is the distance between the closest points of your sprockets. Measure from the teeth rather than from the rim. It shouldreally be from the point where the cord hangs, but that changes all the time, so this'll do.

Now draw a line for the top edge of your machine. It should run exactly in between your sprockets, between the two motor shafts.

Draw another horizontal line, exactly 120mm lower than your top edge you just drew. This is where you'll put the top edge of your page. You can't expect to draw muchhigher than this.

Draw a vertical line down the exact centre of your machine. Where this vertical line crosses your top edge of page line is your home point. The machine knows where itis, you know where it is. You both agree, and it's where everything starts from.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 18: Finish configuring your controllerOpen up your polargraph.properties.txt configuration file, and change the values for:

machine.widthmachine.height

entering the values you just measured, in millimetres. Height isn't actually that important since it doesn't affect the geometry, but it does affect how big it appears on yourscreen, so make it accurate if you have enough screen to do that.

My machine is 712mm wide and 980mm tall, so I enter

machine.width=712machine.height=980

You can also change the page width here, and the page position. Unless you have a wider machine than this, leave controller.page.position.y as 120mm though. Thisvalue corresponds to the lines you drew, and affects your home point.

Other than that, page size and position is a purely visual aid to let you size your drawing properly. It doesn't centre the page automatically, so calculate the x (horizontal)position by doing (machineWidth - pageWidth) / 2.

Advanced editingIf you are using different motors, or different sprockets, change:

machine.motors.stepsPerRev: This is how many steps your motors have per revolution. Well, it's actually _double_ that, because I'm using an interleaved stepstyle in the software - it creates kind of intermediate steps. My stepper motors have 400 steps per rev, so I enter 800.machine.motors.mmPerRev: This is how much cord is extended per revolution. It is essentially the circumference of the sprockets, though with these beadedcords, it's actually the length of 16 bead sections.

Now save your file, and restart the app!

Step 19: Upload your measurements to the machineSo now you should see the size has changed on-screen so the controller knows what the real size of your machine is. But the machine itself doesn't!

You need to upload it by pressing F3 (details) and clicking Upload size . This saves the new size into EEPROM on the arduino, so it'll stay there even when the power islost. Unless you change the sizes, this is the only time you have to do that.

If you're curious (and why wouldn't you be?) Download size does the opposite - it set's the machine size in the controller to be whatever the hardware has saved. Thismight be useful if you delete your configuration file sizes and don't want to measure it all again.

But remember that the configuration file doesn't ever get updated until you click save properties . So remember that if you make changes you want to keep.

Step 20: Now really make it move!

You need to calibrate the machine before each drawing session. This involves telling it where the pen is. You do this by clicking Set home on F1-Input and thenphysically moving the gondola so that it directly over the home point that you worked out earlier.

Clicking Set home locks the motors, it applies power, so they will hold the gondola there for as long as you want.

AND THAT'S IT!

Use Move pen to point to move the gondola around the drawing surface. The noise should be smooth, and the motion also. If you find your motors slip - most likely nearthe extremes of the the surface, or when you're moving fast - you'll need to recalibrate. As soon as the actual position of the gondola gets out of sync with where themachine thinks it is, then your geometry is all off and your drawings will be distorted.

The standard maximum speed 800 steps per second, and the acceleration is 400 steps per second (per second). While the queue is running, you can increment anddecrement the top speed with + and - , and the acceleration with / and * , in blocks of 25. These commands also skip right to the front of the queue too - they're priority.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 21: Choose what to drawSo that's the hard bit done - now load a drawing, select an area to draw, and choose a drawing style.

On F1-Input click load image and browse to an image to try. Some work better than others, but it's all to taste, so just experiment.Click Select TopLeft and click where you want the top corner of your image to be. You'll see that the selection function changes to Select BotRight once you'vedone that.Click somewhere below and to the right of your first click to designate how wide you want your image to be resized to. You should see a red box appear (see pic)This is the selection area. Normally you use it to select which area of the image to render, but here we're using it to resize the image first.Click the Resize image button. Your image should change size.Click the Move image button and you will be able to move the image around to better place it.Use Select TopLeft and Select BotRight to choose the area you actually want to draw.Go to F2-Density Preview to see what detail is being captured.Use the buttons for rowsize up and rowsize down to change the size of the "pixels", bearing in mind that smaller ones take longer to draw.Use the buttons for inc sample size and dec sample size to change the contrast of your image. This is the size of the area that is sampled when choosing thedensity (pixel sample area).

Remember, that once you've found a setting you like, you can save it to the properties configuration file by doing F3 , then save properties . If you don't, it'll all disappearwhen you restart.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 22: Choose a pixel styleCurrently there are four pixel styles.

Shade Square wave - the standard. Pixel density is translated into a square wave pattern. Darker pixel = more waves = more ink.Shade Scaled square wave - the half-tone effect. Instead of changing the number of waves, this one changes the size of the square that gets drawn. Darkerpixel = big pixel = more ink.Shade Solid - used for multi-layer chroma keying effects. This shades every pixel at maximum density, no variation.Shade scribble - noisy effect. This is like a randomised pixel - a number of lines are drawn, but their direction and length are random (within the boundary of thepixel). Darker pixel = more lines = more ink.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 23: Load it up and get scribbling!Load a pen in the gondola just by sticking it in with a bit of blu-tack, so the tip peeps out just a bit.

Stick a piece of paper onto the surface.

Press go!

I've had best success with non-bleeding pens and paper. I like using a very smooth paper like bristol board, along with hard-tipped fineliner pens. Here in the UK I canbuy these ZIG Millennium pens quite easily, and they're really good. Pigma MICRON seems to be a popular US pen in the same kind of vein.

For coarser drawings, a thicker tip is good, I've used regular sharpies regularly, and though they bleed badly, they are vibrant and solid.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

Step 24: Pen lift servoIf you fasten a little servo motor to the gondola, you can use it to lift the pen off the page. There are two servo connectors on the motorshield, if you connect up SER1,then this will respond to commands sent to the machine. I just use the control horn to poke through the gondola and lever against the surface.

The commands can be issued manually by using # or ~ to raise or lower the pen. This is not very subtle, but it works well enough to prevent the pen from leaving a bigbleedy mark at the end of the drawing. These commands are automatically added to the beginning and the end of the queue when you do a drawings.

Step 25: Pen thicknessThe size of the pen tip controls how many waves the machine can fit into one pixel. If you have a pixel that is 20mm square, and you have a 1mm pen tip, then you canonly fit a maximum of 20 lines in before it's at it's maximum density. Adding more ink then won't make it any darker.

If you then swap out the pen and put in one with a 0.5mm tip, 20 lines will no longer completely fill in the pixel, now it will require 40 lines to fill it. The machine works outthe maximum possible density based on what sized pen you tell it you've installed.

You can change the pen setting by using the [ and ] keys, each one changes it in increments of 0.05mm. The size that was last sent is shown in the info overlay on theleft.

Test pen widthsThere is a kind of calibration function to test pen widths too, this draws a sequence of pixels at maximum density, but it increments the pen width setting between eachone.

The following properties (from polagraph.properties.txt) control the starting size of the pen, the ending size, and the size of the increments.

controller.testPenWidth.startSize=0.6controller.testPenWidth.endSize=2.0controller.testPenWidth.incrementSize=0.1

The above settings will draw the first pixel as if it has a 0.6mm sized pen, then draw more, each time incrementing by 0.1mm, until it is 2mm.

http://www.instructables.com/id/Polargraph-Drawing-Machine/

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Comments

7 comments Add Comment

 Wesley666 says:  Nov 14, 2011. 10:31 PM  REPLYIt is said that 1000 monkeys give typewriters and infinite time would eventually type the entire works of Shakespeare, unlike most of my writing, which wouldtake 10 monkeys 10 mins! Haha! I love that saying though, and great job on the 'Ible!

 Euphy says:  Nov 15, 2011. 1:04 PM  REPLYThanks, it's the problem with mistaking activity for creativity. Part of the attraction for this, for me anyway, is that it is so slow, and the variability in it. If adrawing is going to take a day to complete there's a strong encouragement to treat it with a bit more respect :)

 rimar2000 says:  Nov 15, 2011. 11:49 AM  REPLYGENIUS!

 Euphy says:  Nov 15, 2011. 12:59 PM  REPLYThanks very much for the patch!

 PaulMakesThings says:  Nov 14, 2011. 9:38 PM  REPLYThis looks awesome, I really think I will build one.

 Euphy says:  Nov 15, 2011. 12:59 PM  REPLYIt was actually dead easy to make - particularly if you already have a stock of bits and pices. Finding a big flat board was the hardest part! Thanks!

 jquiring says:  Nov 15, 2011. 8:28 AM  REPLYCould you get this to work with 4 colors (CMYK)? You could probably create some unique artwork and make some money (You could probably sell somemonochrome artwork as well).