squeeze one corner of the base, it curls in that direction. The “rungs” of the
ladder keep the fin gripper more or less in the same pointy triangle shape.
On a fish, this kind of tail can push against the pressure of the water with
more force. On a robot hand, two or more fin gripper fingers can be put
together to make a claw that curls around objects without crushing them.
This paper version of a fin gripper finger is based on a paper model Festo
offers for students, but it’s been simplified to use only one strip of paper.
You can create a fin gripper claw by connecting two or more fin grippers to
a “wrist.” When you pull the fingers in, they press up against whatever you
want them to grab and hold it tight.
WHAT TO EXPECT
• Time Needed: 1 hour
• Cost: Less than $1
• Difficulty: Easy
• Safety Issues: Be careful when poking holes through the cardstock
SKILLS USED
Folding, measuring, cutting along lines, poking holes safely
SUPPLIES
• 2 fin gripper finger templates, or two strips of cardstock or other
heavy paper or thin cardboard, about 11 inches by 1 1/2 inches
• Templates for the tube, tube bottom, and springy base, or three
pieces of cardstock in these sizes:
• 1 skinny strip, 1 1/2 inch by 11 inches wide
• 1 fat strip, 4 inch by 11 inches wide
• 1 circle 3 1/2 inches across, with 1-inch tabs on opposite sides.
• Disposable drinking straw
• Scissors
• Sharp pencil
• Tape
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Making Simple Robots, 2nd Edition
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