The hands free toothbrush is a project made by Michael Mitsch, Ross Olsen, Jonathan Morataya, and Mitch Hirt. We wanted to approach a problem that could have a fun solution to build, so we decided to make something that could make it so you didn't have to stop what you are doing with your hands in order to brush your teeth. Yes, with this invention you can continue to text, watch youtube, knit, play video games, or even build more projects with your hands while brushing your teeth.
The photo above shows the finished product. The whole arm piece rotates on a servo motor connected to the base and the toothbrush is driven forward and backward by a DC motor. The gears allow the toothbrush to move in a circle without rotating. The brush starts when someone comes within 30 cm of the ultrasonic sensor plugged into the breadboard. It will brush the middle teeth, turn and get your left teeth, then turn and brush your right teeth.
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Step 1: Step 1: Aquire All the Parts
- Servo motor with metal gears (Tower Pro MG 90S Micro servo)
- DC motor with gear box connected (find here: https://www.adafruit.com/product/3777?gclid=EAIaIQ... )
- Servo topper and servo screws
- Breadboard, wires, AA batteries
- NodeMCU (Micro controller for this project. Alternatives could be used easily and set up easier.)
- Ultrasonic sensor (HCSR 04)
- Motor driver https://www.kr4.us/SparkFun-Motor-Driver-Dual-TB66...
- Super glue
- Duct tape
- Nut x12
- 12mm screw x2
- 25mm screw x4 (I only showed 1 in picture. You actually need 4)
- 30mm screw x4
- Small L Bracket x2 (They look like this https://www.grainger.com/product/1WDD4?gclid=EAIaI... pretty easy to find at hardware store)
- Feet for the base that can stick to the laser cut base
*The screw and nuts are all M3 standard parts. If you are not familiar with screws just get help from someone at a hardware store. They are normally really great at pointing people in the right direction.*
The PDF named combo contains everything you need to laser cut for this project. The stroke width on the lines in the PDF is .003 point and the color of the cut lines is 255,0,0 RGB. We cut all the laser cut pieces out of acrylic because it is sturdy and looks cool, but other material could be used. The holes in the laser cut pieces are sized to fit a screw's diameter minus the threads so a 3M screw will screw into the holes.
Sounds like a lot of parts but the assembly really is not very hard!
Step 2: Step 2: Assemble the Base and Arm
The base was taken from a great robot arm project. They detail the assembly of the base in this instructable https://www.instructables.com/id/Pocket-Sized-Robo... In this project we decided to replace the 20 mm screws with 30 mm screws so the motor would be more elevated so we wouldn't need very tall feet. Be careful when putting the motor into the smallest piece because that piece is very easy to break.
The first step of putting together the arm is connecting the motor to the T. Put the white part of the motor through the T as it is in the pictures then attach the small gear. It should be a tight fit. Next, Use the 25 mm screws to screw the motor onto the T. This only takes a few turns so try to make the motor as straight as you can.
Next, screw the 2 12 mm screws through the other holes that the centers of the lager gears are located in the pictures. The gears will slide on and be able to spin on the screw. Make sure the holes off the center of the large gears are both right above the center. Tighten two nuts against each other on top of the larger gears. Leave just enough room for the gears to still turn easily. We use two nuts on each so the screw will not move as the gears turn.
Finally, add the piece that holds the toothbrush. Put a nut on both 25 mm screws left, then the piece that holds the toothbrush, then two more nuts on each screw. Do not tighten the nuts yet. Screw both 25 mm screws into the larger gears as far as they can go without keeping the gears from spinning. Tighten the nuts as they are shown in the above view. Leave room for the toothbrush holder to spin on the screws.
Step 3: Join the Base and Arm
We decided to use the two small L brackets here. First we super glued the bracket to the bottom of the T. It would help to have something to hold that together while it dries but you can hold it with your hands for as long as the super glue recommends. Once that is dry, duct tape it so it's even more secure then glue the bottom of the bracket to the base on the piece that looks like an H and add more tape. The brackets should be spaced so they are flush against the middle of the servo arm. Hold it like this while it dries or prop it against something for a while.
Step 4: Step 4: Wiring
The Node MCU excluded from the breadboard in my tinker cad picture, but it should be inserted so the on the right so it lines up with to pins I pointed to with the arrows. The 3V3 pin and ground pin on the Node MCU should also be connected to the + and - respectively on the breadboard. There are a lot of wires going different ways so I would advise color coding the wires as I have. The NodeMCU pins used correspond to the pins used in the code so if you change the pins used here remember to also alter the program.
Step 5: Step 5: Tell the NodeMCU What to Do
Put our code onto the NodeMCU.
There are tutorials to set up a NodeMCU online if yours is not working yet. If that's annoying, you could use an Arduino instead and translate the program. The program basically just sets up the ultrasonic sensor then, if there is something within 30 cm of the sensor, the brush cycle starts. The brush cycle is 1. the servo turns to the middle, 2. the DC motor turn forward a second then backward a second 10 times, 3. the servo turns to the right, 4. DC motor movement repeats, 5. servo turns to the right, and 6. DC motor repeats movements again.
Step 6: Step 6: Brush Your Teeth!
This step is victory. At this point you no longer have any use for your hands in your morning routine. Test out the robot and tell us how it worked for you and what improvements you made to our design!