Introduction: Ghost on a String
Ghosty slowly climbs a piece of fishing line--reverses direction when his head hits the top, then slowly sinks down and repeats the process.
My wife, Annelle, made the ghost and I made the mechanism. The Arduino motor shield senses extra current when the ghost "binds" at the top and this causes the software to reverse the ghost. After several seconds of slowly sinking downward, the ghost reverses and climbs.
Arduino Motor Shield
Servo motor (metal gear without end stops)
9 volt battery
9 volt battery holder
3d printed parts
Six 3mm screws
Heat shrink tubing
Fishing line, 8 pound or stronger
Paper or plastic plate
Styrofoam ball (3 inch diameter or larger)
Large plastic bottle
Clear plastic wrap
Seven pipe cleaners
Disposable tin container
Remove screws from servo motor. This motor was selected because 1) It has metal gears, 2) It has no end stops.
Cut wires to motor and potentiometer. Remove circuit board.
Solder wires to motor leads and insulate the connection with heat shrink tubing or electrical tape.
Bring wires out and replace screws on motor.
Connect pulley to servo horn using 3mm screws.
There is a small raised ridge between the two screw holes on each end of the servo motor. File this away (the plastic is soft and this is easy to do).
Mount the motor using four 3mm screws.
Secure the pulley to the servo motor using a screwdriver and the servo horn screw (comes with the servo motor).
Attach the battery/Arduino holder to the motor mount. I melt the pieces together using a soldering iron, but it could be glued.
Thread the long plastic (3d printed) screw into the 3d printed "head."
Thread the head assembly to the motor assembly.
Attach Velcro to the side and end of the battery/Arduino holder.
Secure the battery and Arduino using Velcro.
The 9 volt battery cable goes to the power in terminals of the Arduino motor shield. The motor is attached to + and - for "motor A." The software sketch is loaded to operate the system.
Secure fishing line to pulley. I used 8 pound fishing line (more for strength, less for invisibility). I drilled a small hole in the side of the pulley and tied the line through that hole.
Gather material to make the ghost.
Set plastic bottle on paper plate and put the styrofoam ball on the bottle.
Wrap the ball with clear plastic wrap (to prevent sticking).
To make an arm, braid or twist 3 pipecleaners together, then roll up one end to form a hand. Repeat for the other arm.
Using the one remaining pipe cleaner, twist it loosely around the bottle neck and attach arms as shown.
Cut cheesecloth to desired size.
Pour fabric stiffener into the tinfoil container.
Coat cheesecloth with fabric stiffener and squeeze out excess liquid.
Drape cheesecloth over head and arms.
Repeat step two more times.
Allow cheesecloth to dry overnight.
When dry, carefully pull ghost shape away from the bottle and arms. Remove styrofoam head.
Cut out two felt eyes and one mouth. Glue on ghost.
Using scissors, carefully poke small hole in top of ghost's head.
Place mechanism inside ghost body. Attach fishing line to hook on ceiling. Connect battery and ghost will "float away."
Participated in the
Rope & String Speed Challenge