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

← Previous Next →

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

Tiny CNC Drawing Robot – Cost Estimate

Posted on November 18, 2013 by MakerBlock

A really tiny CNC – a work in progress

One of my goals in designing/building this little robot was to make it really cheap and easy to build. I’d like to think I’m headed in the right direction.

I would estimate the cost of building (a completed version of) this little robot as follows:

3x Micro Servos at $6/each
1x Arduino Uno at $30
30.6g of ABS plastic for roughly $1.53

I’m going to exclude the bits of wire and pen, and estimate the materials cost of this robot at $49.53 which I’ll round up to about $50.00 since I have to design and print a few more plastics parts. Basically, if you’ve already got a 3D printer, plenty of plastic, and an Arduino lying around, there’s no reason you couldn’t have a similar robot up and running in no time for about $20.

It’s my hope to use my newly won Adafruit Trinket 5v, courtesy of Hackaday and Adafruit 1 , it might even be possible to power all three servos off of a single Trinket ($8) and bring the total cost of the project down to around $28 plus little bits of wire and a pen.

Although I give vague building instructions on the Thingiverse page for the parts of this robot, I hope to have an Ikea/Lego style set of instructions ready in the next day or so. So far there are only 8 parts (including the two servo motors), so even a team of monkeys taking a break from writing Shakespeare could manage to assemble one of these in a few minutes.

Tiny CNC Drawing Robot

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Thanks again!!! [↩]

An Itty Bitty Drawing Robot

Posted on November 18, 2013 by MakerBlock

OpenSCAD Rendering of Mini CNC

My daughter and I recently signed up to take part in Make’s Robot Hacks’ project. Make was kind enough to send me a box of parts, including the Make Ultimate Microcontroller Pack and a bunch of servos.

The catch? We had to actually create something and share my progress by November 20. From the time my parts arrived, this was exactly 14 days. 🙂

I had a number of ideas about what I wanted to make – an automated Robo Hand, electronically released spring loaded wings, a little servo-powered walking robot, and a dozen of other smaller ideas. My daughter’s ideas were significantly more ambitious – flying, wall crawling, dancing, hearing, seeing, talking, thinking robots.1 2 The idea that I kept coming back to was a tiny little CNC robot using servos powered by an Arduino – something I had first seen in February of 2012 with Piccolo – the tiny CNC-bot by the Diatom Studio team.

My adventures building robots aside, I still consider myself a “newb.” However, I knew the basics of what I needed to accomplish:

Drive three servos with a single Arduino
Make each servo drive an axis of movement
Figure out a way to translate 180 degrees into linear movement

So, for what it’s worth, here’s my process:

Driving Multiple Servos with a Single Arduino

Since I had never (!) driven a servo with an Arduino, I needed to figure out how to manipulate at three servos at the same time. Fortunately, the Arduino “Sweep” example explicitly states that it’s capable of controlling eight servos.

Connecting them was significantly simpler than I was anticipating. For the Batan B2122 servos I had, the brown wire was ground, orange wire was positive, and yellow wire was the “control” that would have to be connected to one of the Arduino’s digital out pins.3 The easiest way for me to wire up the three servos was through a small breadboard.

Once the servos were wired up, it was a matter of loading up the Sweep example and driving a single servo back and forth. By adding a few lines, I was able to drive two servos, and then three.

Using a Micro Servo Motor to Drive an Axis of Movement

The Batan B2122 micro servos are not continuous rotation motors – they only have a 180 degree range of movement. Most CNC machines use stepper motors which are strong, fast, precise, and can rotate continuously forwards or backwards. Servo motors, by contrast, are smaller, cheaper, slower, and unless they are specifically designated as “continuous rotation” have a limited range of movement.

I considered two different ways, each with their own merits, of using a limited range of motion motor to drive an axis of movement. The first way I considered was using a spool and twine to drive each axis – similar to the Printrbot Simple and WaterColorBot. This is an excellent and cheap alternative to using expensive precision toothed belts to control movement. The reason I didn’t use this method is that it would have required a spool for the twine, and some form of rails or metal rods, and of course twine. My concern is that this would have been a bulky solution for such a small robot.

The second method, the one I decided upon, was to use a rack and pinion to turn the rotational motion of the servos into linear motion. One benefit of using a rack and pinion is that the rack itself removes the need for rails or precision rods, spools, and twine – all while providing a sturdy framework for adding additional axes.

Translating 180 Degrees into Linear Movement

As I alluded to above, the micro servos only have 180 degrees of movement. Thus, a gear (or pinion) attached to a servo would only be able to drive the rack by 1/2 of its circumference (or 180 degrees). Keeping that in mind, I chose a gear size that would produce the desired freedom of movement. I settled on a gear radius of about 20mm because it created about 2.5 inches or 62.8mm [ (2 * π * 20)/2 = 62.8 mm] of movement.

Moving a pen over a 2.5″ square would enable me to create nifty little robo-drawn post-its, bespoke business cards, or an auto-signature device.

Here’s what I have so far:

Next Steps…

Since the robot isn’t actually capable of doing a whole lot yet, I’ve got a bit to do still:

I need software to interpret XY coordinates or GCode into rotational degrees
Get write a Processing or Python script to send the XY coordinate or GCode to the Arduino
Slightly redesign the two gears (well, pinions) so that it’s easier to attach them to the servos
Create a new Y rack that can hold the third servo (for the Z axis) and a pen for drawing

Since I’m only intending to use this little CNC for small drawings, I don’t really need a huge Z axis lift – even a few millimeters should be sufficient. I was considering cheating a little and just making the “Z axis servo” just lift the front of the robot off the surface.

Even though I’ve got a bit of work ahead of me, I’m pretty happy to have a working proof of concept of a robot of my very own design!

If you would like a little robot like this of your very own, you can find my 3D printable files on Thingiverse and the Arduino code is pretty much the stock “Sweep” example. Stay tuned because I’m looking forward to turning this into a legit itty-bitty CNC drawing robot.

Tiny CNC Drawing Robot

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Just put the words on a microchip and put the microchip in the robot’s head, Daddy [↩]
Thanks pumpkin! [↩]
If this seems like Greek to you, as it did to me just a few weeks ago, I’d recommend picking up a Mintduino kit and blinking a single LED. You’ll be able to blink two LED’s in no time! [↩]

Maker Artist Ytai Ben-Tsvi and his IOIO Board Plotter

Posted on November 5, 2013 by MakerBlock

Ytai showing off his plotter art at Codame 2013

Easily one of the most memorable aspects of exhibiting at this year’s Maker Faire Bay Area was getting to meet and interact with lots of other Makers. Ytai Ben-Tsvi had built and brought a pen plotter of his own design – and it was amazing.

Ytai’s pen plotter used an Android tablet, his IOIO OTG board1 , two stepper motors, two comically large spools, and lots of custom code to turn pictures taken with the tablet into instant portraits on the fly.

His plotter was everything a Maker Faire exhibit should be – highlighting the intersection of art and technology while inviting the audience to be a part of the action. Can you believe this guy was reluctant to call himself an artist?

After Ytai was invited to participate in the Codame 2013 art-tech festival2 he decided to create an entirely new drawing algorithm to turn images into a single line drawing which appears to be sharp scribbles up close and a detailed image from a few meters away.

Photo transformations with Ytai’s ScribblerDemo

What I love about Ytai’s drawing process is that it produces a drawing with a sense of whimsy and movement without the hard number crunching necessitated by a Traveling Salesman Problem3 style drawing.4 By allowing the algorithm to have lines cross over one another, something the TSP method eschews with its own aesthetic, Ytai’s drawings essentially gets “for free” extra dark patches where lines closely intersect.5

Looking at this drawing, it seems to me that an SVG created from his algorithm conveys so much more meaning with far less points than a TSP file. At least for my own PlotterBot, far fewer points would also mean a much faster, and more satisfying to watch, drawing. I would estimate that in the time it took Ytai to cover a wall, I might have been able to create one, perhaps one and a half, drawings. And, as any good Maker does, Ytai has shared the fruits of his hard work in the form of the source code on Github.

Plotter Profiles

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Ytai’s succinct description of the IOIO board says it all, “The IOIO-OTG is a printed circuit board for electronics hobbyists and prototypers, which addresses a very common problem: how do I use my {computer, tablet, phone} to control my {robot, dish-washer, cat-feeder, etc.}.” [↩]
An art-tech festival?! Why the hell aren’t there more of these things?! [↩]
Link to blog post showing a method [↩]
Doesn’t exactly hurt to have a cute kid as a subject either [↩]
Having played with TSP drawings a lot, I have discovered that finding the right balance between lightness versus darkness and simplicity versus complexity and quick versus glacial to be… maddening. Like H.P. Lovecraft maddening [↩]

Hackaday Logo Trinket Contest Entry: Hackaday Inception

Posted on October 27, 2013 by MakerBlock

This drawing of the Hackaday logo is about 30″ square, shaded with smaller logos from about 1/2″ to 2″ in height

Hackaday is running a contest to give away 20 Adafruit Trinkets to people who put the Hackaday logo on something, preference given to the largest and smallest incarnations.1

For your consideration, I offer a large Hackaday logo drawn by my wall mounted pen plotter, shaded in with smaller Hackaday logos.2 I’m honestly not at all sure how many I used, but there’s a lot.3 For this drawing, I used an Inkscape technique documented by Kongorilla on Sandy Noble’s Polargraph forums.

This was my first time trying this method of using Inkscape to generate vectorized halftones, but I really liked the effect. Shading a much larger image with very tiny images opens up a lot of possibilities. I could draw a big picture made of lots of tiny almost subliminal images, a big block of text shaded in by other text which negates the larger text, or perhaps a lot of sensible tiny images that create a much larger image that’s difficult to really grok until you step farther away.

To make the large vector drawing for my PlotterBot, I had to manipulate the original Hackaday logo SVG file. Here were my steps:

For the vectorized halftones technique, I needed a bitmap version of the Inkscape logo. I opened the Hackaday SVG in Inkscape and then took a screen shot of it.
I pasted the screenshot into GIMP, cropped it to just the size of the logo, and saved it as a JPG file.
Next, I needed a smaller version of the Hackaday logo to use as the vectorized halftone. For this, I opened the Hackaday logo in a separate instance of Inkscape. I deleted the eyes and nose, then joined the wrenches to the skull, and deleted any lines that interesected, so that the PlotterBot could draw the outline of the entire logo with one continuous path. If I didn’t do this, then every single instance of the tiny Hackaday logos would have required four pen-ups instead of just one, the drawing would probably have taken more than 8 hours4 , and it wouldn’t really have added much to the overall aesthetic.5 I’ll refer to this as the “eye-less Hackaday logo.”
With the Inkscape window still open with the Hackaday vector logo in it, I imported the JPG/bitmap version from GIMP back into Inkscape. I matched the bitmap version as closely as I could over the vector image.
1. Apparently, you can only apply the vectorized halftone technique to bitmaps. If you try to apply it to a vector, you won’t get anything.
2. Since the Polargraph software I use can’t draw a combination of a bitmap and a vector, the bitmap image will be removed later – leaving the large vector drawing underneath. The large vector drawing was necessary to get the large outline of the full Hackaday logo.
Once I had the large Hackaday vector logo with the bitmap version of the Hackaday logo laid over it, I measured and took note of the bitmap image in pixels6 , and pasted in the eye-less Hackaday logo into the top left corner. I then scaled7 the eye-less Hackaday logo so that it was fairly small – about small enough to fit into the wrench on the logo.
To use the eye-less Hackaday logo as the vectorized halftone:
1. Edit -> Clone -> Create Tiled Clones
2. “Trace” tab
3. Check “Trace the drawing under the tiles“
4. Under “1. Pick from the drawing:” choose “Color“
5. Under “3. Apply the value to the clones’:” choose “Presence”8
6. Specify the size of the drawing in pixels using “Width, height:“:
7. I used the “Randomize” tab to randomize the rotation of the eye-less Hackaday logos up to “45.0” degrees.
8. Click “Create“
The result was very cool – but required a lot of trial and error. If the original eye-less Hackaday logo in the top left corner was too large, there weren’t many logos in the finished drawing and it didn’t look very interesting. If the original eye-less Hackaday logo in the top left corner was too small, there would be too many small logos with very little variation in size and the result would have been a mess of tiny squiggles. Once I found a starting eye-less Hackaday logo that struck a pleasing balance between the number of medium and tiny eye-less Hackaday logos, I noticed that there were a lot of instances where a smaller logo just looked out of place. So, I manually deleted some, copied others, and rotated a few to make a more pleasing drawing.
Once I was happy with the drawing, I selected the imported bitmap layer and deleted it – leaving me with the large Hackaday logo vector and lots of tiny eye-less Hackaday logo vectors shading it in. The last thing to do was delete the first eye-less Hackaday logo I had imported into the top left corner of the image.

Here’s a picture of one of the smaller instances of the eye-less Hackaday logos:

Detail of an “eye-less Hackaday logo”

And, if you’ve made it this far, why not check out an animated GIF of my PlotterBot in action?

Go PlotterBot! Draw like the… tortoise?

The drawing took about 5 hours, start to finish.

Here’s the first and second batch of entries so far [↩]
“I decline the title of Iron Cook and accept the lesser title of Zinc Saucier, which I just made up. Uhh… also, comes with double prize money.” – Bender, 30% Iron Chef [↩]
If you’d like to try out the SVG file I created, you can download the original Hackaday Logo (3312 downloads ) and my SVG of the Hackaday Logo Inception (3313 downloads ) . [↩]
At which point the Sharpie pen would have given up the ghost [↩]
Besides, using a single continuous path as the vector is what Kongorilla suggested anyhow [↩]
You can just read this directly from the file’s properties or from GIMP [↩]
Selecting the eye-less Hackaday logo and holding “CTRL” down while moving one of the arrows around the logo will change its size but keep its aspect ratio [↩]
For my drawing, I also selected “Size” – which created the smaller little eye-less Hackaday logos [↩]

Building a PlotterBot Arduino Drawing Robot – An Overview

Posted on October 19, 2013 by MakerBlock

Completed PlotterBot

A PlotterBot Arduino-based drawing robot is an easy to build robot you can make from off-the-shelf electronics and easily repurposed parts. At it’s heart, this robot uses a microcontroller to drive motors to reel in and out two spools of wire to move a pen across a vertical surface. One of the best thing about this particular robot is that it is extremely forgiving. Your robot will still be capable of drawing huge amazing pictures even if you don’t mount the motors perfectly level, your spools aren’t quite symmetrical, or if your measurements are a little bit off.1

Here’s an overview of what you’ll need to do to build your own PlotterBot:

Parts
1. 2x Stepper motors
2. 1x Servo motors (if you want to do pen lifts)
3. 1x Arduino Uno or greater
4. 1x Adafruit Motor Shield
5. USB cable
6. Power adapter
Hardware and Supplies
1. Assorted wire, nuts, bolts, screws
2. Monofilament fishing line
3. Solder
4. A project box or the stuff to build one with
Tools
1. Soldering iron
2. Power drill
3. Screwdrivers, hex wrenches
4. A 3D printer is very helpful – but not necessary
Assembling the Electronics
1. Build the Adafruit Motor Shield
2. Connect the Shield to the Arduino
3. Load the Polargraph firmware
4. Connect motors to the shield
5. Test the assembled electronics
Build the Robot
1. Connect spools to the stepper motor shafts
2. Mount the motors in your project box
3. Wind monofilament fishing line on the spools
4. Tie the fishing line to your pen holder
Calibrate the Robot
1. Measure the diameter of the spools and distance between motors
2. Save your settings and upload your measurements to the robot
Draw
1. Load pictures into the software and start drawing

Keep in mind that once you have the basics (an Arduino, the shield, and two steppers) you can change the setup to suit your needs. I’ll discuss more about each of these points, and turning each one into a separate blog post (or more!) soon.

Finally, join the PlotterBot newsletter now so you don’t miss out on the latest information!

Of course, it will do a better job if you get everything right… [↩]

PlotterBot Frequently Asked Questions

Posted on September 22, 2013 by MakerBlock

Display Posters at Maker Faire Bay Area 2013

Although I’ve helped out at the MakerBot booth several times in prior years, this was the first time I had my very own booth.1 I had a great time answering questions and explaining how the robot worked. I thought you might be interested in some of the questions:

What holds the pen up? Magnets?
- My PlotterBot suspends the pen holder by fishing line – which is nearly invisible from more than a foot or so away under normal lighting. Under very bright light, the shadows of the fishing line do start to appear. However, from more than a foot or two away, it looks like the pen holder is floating around the surface of the paper. Unless you notice the motors turning the pulleys, it almost looks magical.
- Sandy Noble’s Polargraph uses beaded cord and Der Kritzler uses toothed belts. While these machines lack the “magic quality” one gets from using fishing line, the are a capable of more repeatable accuracy.
What software do you use?
- I use Sandy Noble’s Polargraph firmware and software, running on an Arduino Mega shield (“Polarshield SD“) of his design. I purchased most of my electronics directly from Sandy and I can’t recommend them enough.

Maker Faire Display Board

What kind of accuracy/resolution does it have?
- This was a difficult question to answer. To explain I pointed to the large text banner at the top of the project board next to my robot. You can download all of the materials from my PlotterBot Maker Faire exhibit here or you can see a copy of the text just after I managed my first successful pen lifts.
- I would estimate that the robot could probably manage to just barely draw from around 30pt font to an arbitrarily large size. However, if you used beaded cord or, better yet toothed belts, and small sprockets or gears in conjunction with a fine tip pen you could probably manage even finer repeatable accuracy.
How fast can it go?
- I suggested that the entire robot adhered to that most basic of all engineering principles – “Good, cheap, and fast – pick two.” It’s fairly cheap and easy to build and yields pretty amazing results, but there is a practical upper limit to the speed with which you can operate the robot. If you run it too fast, the motors may skip steps resulting in poor results. Also, running it too fast would likely also cause the pen to skip across the drawing surface or might not give the pen enough of an opportunity to leave an ink trail. For best results, I try to find a speed that works well with my pen holder and pen to draw quickly enough so the pens don’t bleed much and slow enough to get good results.
How big can it draw?
- Basically, an unlimited size. There are some practical limitations from the Arduino software which suggest that a 63 meter diagonal is the biggest you can accomplish with Sandy’s software. However, with some more effort to tinker with the code, there’s no real reason why even larger sizes wouldn’t be possible. Also, the larger the pulleys/sprockets/gears the larger the drawing could be as well. Bill Ola Rasmussen posted some very interesting mathematical considerations regarding line tension and the practical limitations of resolution at the edges of the machine’s capabilities. Basically, if you want a big drawing, you need a really big robot.
- While all this is very abstract, it’s also nice to show how these kinds of robots can reach amazing proportions. Sandy has used a Polargraph to draw across huge wall sized installations. (About 20 feet wide). Two similar machines, Hektor which draws in spraypaint and Viktor which draws in chalk, were used to draw on entire walls.
What kind of pens do you use?
- The short answer is Sharpies and art marker pens. I like the “Prismacolor Premier Chisel Fine Double Ended Art Markers.” I’ve since devoted an entire post discussing the best pens and markers to use with a wall drawing robot.
How long does a drawing take?
- 2′ x 3′ drawing typically takes about 4-6 hours depending upon the density of the drawing and thickness of the marker line. The longest drawing I’ve ever done took about 8 hours. And it was AMAZING.
How do you create these drawings?
- The software basically translates normal images (JPG) into very pixelated versions of themselves and then into instructions the robot’s firmware understands. The process is a little more direct for vector drawings, converting the SVG files directly into instructions for the robot. I can send the instructions to the robot either over USB or saving them to an SD card which it reads.
How much did it cost to make?
- I sourced all the parts I needed for my first robot, rather than trying to scrounge for motors and wire. As a result, it probably cost around $100 for a machine that used an Arduino Uno and an Adafruit Motor Shield and had to be tethered to a computer via a USB cable. For someone willing to tear apart old electronics and hack things together from scrap wood, it could probably be built for around $30-$50. The robot I had on display cost around $250 in electronics, $10 for the cost of the printed plastic parts, about $40 for the wood and hardware, and a wooden box left over after a catered event. To buy plastic parts, all the hardware off the shelf, and electronics would probably cost about $500.

Well, I did share the space with my daughter! [↩]

What is the best paper to use with a PlotterBot?

Posted on September 22, 2013 by MakerBlock

This is not the paper you’re looking for. Move along.

The choice of paper in a PlotterBot is nearly as important as the choice of pen or marker.1 Some of these considerations are:

Quality. Is the paper archival quality? Will it yellow or discolor over time or when exposed to light?
Expense. Is it expensive? Sometimes things happen during a drawing and you end up with a diagonal line going across the entire sheet of paper. It’s annoying when you’re using cheap banner paper, because you might have lost a few hours of work. It’s really painful when you’ve bought 10 sheets of super nice paper for $50 and it’s totally wasted.
Finish. What is the finish? Smoother/glossier papers will tend to bleed less, but they will also tend to smudge more and possibly take the ink less well. Papers with a flat/matte finish will tend to smudge less, but be more absorbent and bleed more. Paper with a grain or tooth to it will also wear down on your felt tip marker or accumulate paper fuzz on the tip of your pen.
Portability. Will it roll? If you’re selling or transporting drawings, you don’t want a stiff board that would crack rather than roll into a hard mailing tube. Thinner papers that roll better will also accidentally wrinkle or crease more easily.

Cheap banner paper roll of choice

Cheap Banner Paper

So far my favorite paper, as crazy as this sounds, has been the cheap banner paper rolls I buy from the local Staples office supply store. These rolls are about $5 each for a 30″ wide roll that’s 52 feet long. Since each of my drawings tend to be about 2-3 feet in height, I can get more than a dozen drawings out of each roll. This paper has a mild gloss to it, very little tooth, rolls and unrolls easily2 , takes Sharpie ink well, and doesn’t bleed or smudge much. I’m pretty confident that this paper isn’t archival quality, but given that each drawing is about $0.40 worth of paper, it’s a trade off I’m willing to accept.

There is always an informative discussion on paper choices over at Sandy Noble’s Polargraph forum. Although I haven’t tried these other papers, here’s a short list of some of those recommendations.

Strathmore 300 Series Bristol Board used by Sandy Noble

Bristol Board

Sandy Noble uses Bristol Board as it is smooth (so it doesn’t gum up the pen tip) and easy to roll. He found that it tended to hold the curl of a roll once it had been held that way.

The largest sheets of 300 Series Bristol Board Strathmore makes is 22.5″ x 28.5″. You have your choice of vellum or smooth. I can only seem to find these listed as 23″x29″ and sold by the sheet starting from $1.50/sheet. However, they also sell rolls that are 42″ wide and 10 yards long which seem to go for about $50/roll. ((My robot was specifically built to accommodate a 30″ roll of paper, but could be adjusted without too much modification to draw on an even larger scale and accommodate larger rolls.))

Tango Advantage Digital 10pt C1S used by Kongorilla

Tango Advantage Digital 10pt C1S Paper

Kongorilla recommends using Sharpie Ultra Fine tip markers on Tango Advantage Digital paper.

The largest sheets of Tango Advantage Paper I can find online are 19″ x 13″ – which is on the small side, given my robot’s capabilities. A pack of 450 goes for about $80, which brings the price to around $0.18/sheet.

Borden & Riley Paris Paper used by Gensior

Borden & Riley Paris Paper

Gensior recommends Borden & Riley Paris Paper as he finds it smooth, flexible, strong, semi-gloss finish, and seems to not bleed with the Pigma Micron pens he uses. He does note that it only comes in white.

I was able to locate some of this art paper online in sizes up to 19″x24″ for $40 for 40 sheets (basically, $1/sheet) and 36″x10 yard rolls for $29.

Photo courtesy of Kristina Alexanderson [↩]
But does wrinkle and crease easily too [↩]

What are the best pens to use with a PlotterBot?

Posted on September 17, 2013 by MakerBlock

The Pen Plotter is Mightier Than The Sword

One of the most common questions from Maker Faire was whether I used any special pens.1

There are a few issues to consider when selecting a pen to use with your drawing robot. First and foremost, the pen needs to be able to write consistently when it is positioned perpendicular to a vertical surface. Secondly, it shouldn’t dry out too fast – since a single large drawing could take as much as 6-8 hours. Third, it should have a large enough supply of ink enough to drawing of choice.

I’ve tried out lots of different kinds of pens – from normal office supply style gel pens, to permanent markers, to expensive art markers. Overall, my favorite pen to use was the art markers, but for most purposes I would probably go with a Fine Point Sharpie.

Prismacolor Premier art markers

Art Markers

Art markers, the kind you’d find at an art supply store, are really great. They come in a variety of colors and the ones I prefer, the Prismacolor Premier Chisel Double Ended markers have a wide and fine tip end to choose from. These particular pens seemed to last a really long time. I was able to draw three or four hour drawings with a single marker. The only downside to these markers are the cost. Amazon only sells these pens in large sets (12, 24, and 72 markers) that average out to about $2-3/marker. While you can buy them individually from your local art supply store, they will end up being about $3-5/pen. That said, if you just had to have a drawing with a particular color marker, you probably can’t beat the color sections from a Prismacolor set.

Sharpies

Sharpie Markers

Sharpies are ubiquitous, come in lots of colors, and are fairly cheap. A pack of assorted colors of Sharpies would probably average out to about $1-$1.5/pen. Chances are your local office supply store runs a deal on these every few weeks. I picked up a pack of 12 colors for about $5 just before Maker Faire this year. In my experience, a Sharpie Marker Fine Point would be good for about two big drawings. Sharpie also sells pens – which might work even better since they have a smaller surface area and may not dry out as quickly. I’ve experimented with trying to “revive” a dried out Sharpie by soaking the pen tip in rubbing alcohol (as I had read somewhere on the internet), but it didn’t seem to do much.

Pilot Precise V5 / V7

Pilot Gel Pens

One of my favorite pens for paper work/office use is the Pilot Gel series of pens. Of these, I prefer their “Precise” line of pens. They only come in a very few colors (red, black, blue, and green), but they are reasonably cheap (less than $1/pen when bought by the box). When used in a drawing robot, you’ll want to make sure they’re mounted at a slight downward tilt. They only come in either Fine Point or Extra Fine Point. For this reason they’re okay for small or medium sized drawings, but not very good for large pictures – as the lines would be too thin and the drawing would take too long.

Pen Reviews on Polargraph.co.uk

Sandy Noble’s website (Sandy is the creator of the Polargraph board and software I use for my own robot) has a great forum with lots of resources including several reviews and recommendations for pens. There’s a review and guide for Sharpies, one user recommended a “KOH-I-NOOR Fiber professional,” and Sandy expressed a preference for a Kuretake Zig Millennium.

UPDATE:

Two Polargraph users, Lanthan and Kongorilla, have posted the results of their tests using various pens, including ball point pens.

Also, be sure to check out the Egg-Bot documentation over at Evil Mad Scientist Labs for suggestions on pens and markers (and other things!) to use with their pen plotter. (Thanks Lenore!) I would point out that those pens were tested using the Egg-Bot, which holds the pen nearly vertically, versus a wall-hanging pen plotter which holds the pen nearly horizontal.

Best Pens for Drawing Robots

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Photo courtesy of Brian [↩]

New PlotterBot Drawing – Calvin & Hobbes on a wagon

Posted on June 8, 2013 by MakerBlock

PlotterBot drawn Calvin & Hobbes on a wagon

The other I came home from work and decided I just had to draw something.1 I decided on the above picture of Calvin & Hobbes and set the robot to work. The drawing is big – about 29″ tall and 28″ wide.

While my tallest drawing remains the Yoda, this is definitely the widest drawing I’ve managed thus far. I’m also pleased with my rather simplistic method of centering the robot.2 If the centering were off, the remainder of the drawing would be skewed. And, as you can see from the horizontal lines, there isn’t any observable skewing.

There are some very mild artifacts in the drawing – spots where the pen wasn’t lifted far enough off the paper, some areas where you can see how the pen lifted up and down, and places where the shading/hatching doesn’t exactly line up perfectly with the outline of the drawing. Even with these minor issues, I’m really happy with the drawing.

I feel like when I don’t “make” something for a little while I get kinda twitchy. [↩]
I’ll be adding a tutorial for this later – it’s a lot simpler than you might think… [↩]