This simple device sits on your desk at work, ready to give you fist bumps throughout the day as you need them. A 3D printed “fist” is moved by a servo attached to a rack and pinion mechanism. An ultrasonic range finder detects when you place your hand near it, and an Arduino Uno controls it all.
Materials:
- Arduino Uno – RadioShack 276 128
- Standard servo – RadioShack 273 766
- Ultrasonic range sensor – RadioShack 276 342
- Misc wires and connectors
- 9V battery connector –RadioShack 270 324
- 9V battery – RadioShack 230 2209
- Slide switch – RadioShack 275 401
- Afinia 3D printer – RadioShack 277 224
- 3D print filament (ABS or PLA) – RadioShack 277 182 or RadioShack 277 163
- Nuts and bolts – RadioShack 640 3018 and RadioShack 640 3011
- ¼” plywood (14″ x 25″)
- Wood glue (optional)
- Rough sandpaper (I used 275 grit)
- Weights (I used misc washers)
- String/wire cable
Step 1: Make cables
To connect the electronics, a few cables are needed. First, make a pair of “splitters” for providing power (5V) and GND to the sensor and servo from the Arduino using female connectors. Since both devices need the same Vcc, the splitters make the wiring easier to put together and more compact when it is assembled.
Next, solder a cable to connect to the ultrasonic range sensor. Use a female connector for the end that the sensor will plug into, and solder the other ends of the wires to individual male headers.
Finally, cut off the female connector at the end of the servo and solder the wires to individual male headers as well.
Step 2: Cut the Base and Slide
Using a laser cutter, cut out the parts for the base and slide out of 1/4″ plywood. I used fairly low settings for my cuts to keep the tolerances correct – speed 20%, power 35%, and frequency 500Hz.
Step 3: Attach Servo
The servo needs to be secured to its mount before assembling the box around it. Simply use four bolts to attach it, making sure that it is facing in the correct direction.
At this point the pinion gear needs to be attached to the servo horn. The part is a fairly close press fit, but the addition of some hot glue ensures that it won’t slip off during assembly. Once glued, the horn/gear attaches to the servo using the screw included in the package.
Read more: Desktop Fist Bumper using arudino