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Basic Mechanisms

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Crank

Steps 1 2 3 4 5 6 7 8 9 10 11 12

Step 1

A crank mechanism transfers the servo’s rotation motion into a swinging pivot motion, like a door.

Popular uses of the crank mechanism include moving mouths and swinging doors. What will you create?

Step 2

Hardware

  • Hummingbird Controller (Bit Controller pictured. The Duo controller will also work)
  • Battery Pack or AC Plug
  • Position Servo (Your servo may look different)
  • Circular Servo Horn

Suggested Craft Supplies

  • Hot Glue Gun
  • Scissors
  • Blade
  • Paperclip
  • Scrap Cardboard
  • Cardboard Box with Flaps (For beginners, we have found the 6x6x6 box works best)
Step 3

Interlock the tabs on one side of the box.

Step 4

Cut a small section (about 2 cm by 5cm) from the piece of scrap cardboard.

Step 5

Unbend the paperclip into an L shape with a small hook on the top.

Place the L- shaped paperclip inside the box. The shorter arm of the L- shaped paperclip should be be centered on the lower flap of the cardboard box.

Step 6

Place a generous amount of hot glue over the shorter arm of the paperclip, then place the small cardboard section over the glue. You’ve just create a linkage point for your crank.

Step 7

Cut off another section of scrap cardboard. This section should be about 7 cm in length and it should match the width of the circular servo horn.

Step 8

Glue the servo horn onto the one end of the cardboard scrap. Try not to get hot glue into the center hole of the servo horn.

Step 9

Trim the excess cardboard around the edge of the servo horn.

Step 10

Push the servo horn onto the servo shaft. This servo will rotate 180 degrees. If you imagine the servo as a clock, with the wire side indicating the top of the clock, align the servo horn so that the arm can swing freely between 6 o’clock and 12 o’clock.

If you are using the HS-311 servo from the Hummingbird Duo kit, your servo will need to swing in the opposite direction.

Step 11

Cut about 2cm of the cardboard arm. Using a blade, poke a hole through the end of the cardboard arm.

Step 12

Feed the hook end of the L- shaped paperclip through the hole at the end of the cardboard arm. Make sure the wired side of the servo is pointed into the box. Use a generous amount of glue to secure the servo to the floor of the box.

If you are using the HS-311 servo from the Hummingbird Duo kit, your servo will need to be pointed in the opposite direction, with the wired pointed out of the box.

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