Doodle Bot 2000

This curious looking drawing toy was my inspiration for the DoodleBot 2000. It is a relatively simple toy that can be found on Walmart shelves that uses a battery-switch-motor simple circuit to vibrate and create doodles with its marker legs. I intended to achieve a similar concept toy using slightly more common items, all of which can be found around the house or bought cheaply from various locations. The DoodleBot 2000 is different than the inspirational toy by including an LED on/off indicator, as well as a method for speeding up or slowing down the spin velocity of the top spinning mechanism. It is also fundamentally different in its assembly and constructional aspects.

Here is a list of all the supplies you will need to assemble 10 DoodleBot 2000s (intended for classroom use)

Constructional Components:

• Common Printer Paper (2 sheets per bot)
• Scissors
• Glue Stick
• Paperclips (2 per bot)
• Clothes pin (2 per bot)

https://www.amazon.com/Home-X-Wooden-Clothespins-S...

• Wobble Weight (3D printed, blob of clay, or any other asymmetric object that can attach to the motor shaft)

https://www.instructables.com/3d-Printed-Gearbox-f... (This instructables by fortzero provides downloadable STL filed for his DC Motor Shaft Fitted gears. Printing any of these will do the job as you'll see further along in my build process)

• Markers (3 per bot, preferably with a thin tip)
• Rubber Bands (2-5 per bot depending on size and strength, 4 or 5 is recommended)

https://www.amazon.com/Alliance-26329-Advantage-Co...

• Empty duct tape roll (low amount of tape left will work too)
• Stapler with staples
• Paper to doodle on

Electronic components:

• Common DC motor + holder (comes with the motors in the link below)

https://www.amazon.com/EUDAX-Strong-Magnetic-Elect...

• 2 AA battery pack with switch

https://www.amazon.com/LAMPVPATH-Battery-Holder-Sw...

• 4 10 ohm resistors (this may vary due to motor load, user discernment is advised)

https://www.amazon.com/Projects-10EP51210R0-Ohm-Re...

• 1 small red LED

https://www.amazon.com/EDGELEC-Diffused-Resistors-...

• Simple wires

https://www.amazon.com/dp/B003J699RW/ref=twister_B...

• Soldering pen + Solder (handled by an adult only!)

https://www.amazon.com/Soldering-Iron-Kit-Solder-G...

https://www.amazon.com/MAIYUM-63-37-Solder-Electri...

• Wire Cutters + Strippers

https://www.amazon.com/DOWELL-Stripper-Multi-Funct...

• Shrink tubing (recommended but optional)

https://www.amazon.com/URBEST328-Assorted-Shrink-C...

• Heat Gun

https://www.amazon.com/Wagner-Spraytech-0503008-He...

***Adult supervision is recommended for any soldering, heat gunning, scissoring, snipping, or any other potentially dangerous task in this instructable.

If you are a teacher looking to have your students make their own Doodle Bot 2000s, that's great! However, you will need to prepare several things in advance in order to reduce in-class processing as well as reduce any risk of a student burning themselves with a soldering iron or 3D printer extruder (although, it could be fun to do a 2-day lesson plan, in which students learn to use a 3D printer as the first lesson, and their test run is the wobbler).

The first necessary task is to solder resistors onto the motor. As I mentioned in the materials list, this can be a finnicky task, since different motors will respond differently to different loads, and also because the motor will be slowed a significant or not significant amount due to the moment of inertia of the wobbler. So, I would suggest trying to build your own Doodle Bot 2000 first, and experiment to see what works best/how many resistors you will need. I found that 40 ohms of resistance was enough to slow down the motor to the point where I could make minor adjustments to the wobbler to get a good range of speeds. Remember, more ohms = less speed, also more moment of inertia = less speed. A slow Doodle Bot 2000 will produce well defined dot circles, and a fast one will be more likely to draw smooth, clean circle patterns.

**Be aware that more soldering will be necessary after a good deal of assembly has taken place (the battery box twill need to be soldered to the motor and LED, and any extension wires if necessary)

The second prep task is to 3D print the wobblers (unless you have another way to create effective wobblers). I printed a solid disk with a protruding cylinder, with a hole the width of my motor shaft. 3D printers tend to print holes a little bit tighter than their measured values, so it's better to overshoot! After all, you can always superglue the shaft if you can't achieve a good friction fit. You could incorporate a notch into the design before printing, but I found I had more control over testing a good size notch just by clipping out the notch with wire cutters. This wobbler served me well, left as it is I had myself a fast spinning, and more importantly oscillating, Doodle Bot 2000. I could slow it down by attaching clothes pin of various cut lengths to increase the wobbler's moment of inertia.

The first thing students need to do is create a base to build the components of the Doodle Bot 2000 on. I made mine by cutting 2 pieces of paper each into fourths and gluing the 8 quadrants into a thicker stack of paper. Alternatively, you could use firm cardboard or maybe even a cardstock. It just had to be rigid enough to poke a few holes in and keep everything together. No matter what material you use, cut it into a circle, about 2cm wider in diameter than the empty tape roll you'll use for the under-body section.

You'll want to attach the battery pack first, squarely in the middle. I found that an easy way to secure it was to bend 2 paperclips each into a sort of a "Π" shape (if that symbol doesn't show, it's a squarish-upside-down U). Poke the ends of the paper clips through the paper disk and then bend them flat to keep the battery pack tight. I also ran one of the wires back though the paper clips for later wiring purposes. The battery pack side is the bottom of the Doodle Bot 2000. and make sure the switch isn't being covered up! You'll need to be able to access it at the end.

Now that the battery pack is in tight, the next thing to add is the motor configuration. Honestly, you might need to get pretty creative with this part depending on what's available to you. My motor came with a white plastic holder piece that came in handy, but if yours does not, there are many many ways to secure the motor... hot glue, super glue, wire, clay, clothes pins, etc.

I started by super gluing my plastic holder piece to a clothes pin as shown, and then glued the clothes pin to the paper disk in such a way so that the upward facing shaft of the motor was perfectly centered on the disk. This is important so that the Doodle Bot 2000 will spin evenly.

The third picture shown here has a few things to note. The red pins are not part of the final design. I took this picture while I was attempting a different design for the legs/marker holders, and it was a complete failure. Also, you'll notice the resistors coming off the motor and going down into the disk. While test fitting where I wanted the motor to go, I left it unwired, then once I got it into place I added the resistors. It is not necessary to do it this way, in fact it's probably easier to wire everything beforehand as I've suggested you do. It is important however to run the wires down through the disk, preferably spaced apart to some degree. work within the constraints of how long your resistors are and what you think will work best, there's no right way to wire it as long as in the end it works. You could also add shrink tubing to reduce any risk of the paper heating up due to the wires, but I didn't and it turned out fine. Just remember, there is still an LED to be soldered on.

To attach the markers to the base, you must first plan where you want them to go. Try to position your markers evenly around the circle (you can use 3 or 4, I used 3). Then, using scissors, make slits on either side of your marker placement that go about 1cm deep into the disk to create little tabs. Fold these tabs down, they'll allow you to attach your empty tape roll to the paper disk using rubber bands and/or glue

Before you get to the tape roll, make sure to connect the battery pack wires to the motor wires. I soldered these together carefully, but you could also just twist them together securely if it's too difficult or unsafe to solder it. The flow of current through this system can be in either direction, it won't matter.

Hopefully, your empty tape roll is large enough to go around your battery pack on the underside of the disk.

This step is fairly straight forward, put the tape roll in place, fold the tabs you previously cut down, and secure them in place with rubber bands or any other method you think will work. Then, I secured my markers to the tape roll one at a time using more rubber bands, marker tips down.

This step is relatively simple, and you may choose to skip it entirely, but if you want to include an LED that lights up when you turn on your Doodle Bot 2000, make sure it wont burn out before you solder it on. I used a fairly medium sized red LED (longer wire is positive, because the LED does care which direction current flows in), and it worked well. Try a test light-up before soldering it just in case though (I had to solder a little bit of extension wire onto my LED)

:)

I made my cover out a quickly cut and stapled piece of paper with a hole in the center for the motor shaft to fit through. My advice for construction is just trial and error, try making a dome-ish looking thing, and trim or restaple when needed to make it fit your Doodle Bot 2000. You also need to cut a small hole for the LED to poke out of. Then, when you have it right, attach it to the paper disk using a few pieces of tape.

Here are 2 examples of the kind of art my Doodle Bot 2000 is capable of producing!

On the left is a looser, more dotted drawing. I accomplished this style art using a higher moment of inertia with a clothes pin attached to the wobbler like you saw in the last step. This caused the motor to spin much slower than it would have without the clothes pin

On the right is a tighter, smoother drawing. I accomplished this style art using a lower moment of inertia without the clothes pin. I just left the black notched wobbler so it spun much faster.

Make sure you have enough room for your Doodle Bot 2000s to roam around! they usually don't stay in the same place for long :)

You can play with adjusting the moment of inertia of the wobbler, as well as the type of marker, the angle of the markers, the spacing and height of the markers too! There's a lot of fun to be had with the Doodle Bot 2000