WHAT TO EXPECT
• Time Needed: 1 hour
• Cost: Less than $10
• Difficulty: Easy
• Safety Issues: Watch out for popping balloons!
SKILLS USED
• Blowing up balloons
• Balloon twisting techniques
SUPPLIES
This build doesn’t require anything fancy. Just make sure you have
extra balloons on hand — they tend to pop!
• 3 twisting balloons and a balloon hand pump
(available in party goods stores)
• Flexible vinyl tubing, 1/4 inches (15 cm) inside diameter
(available in hardware stores)
• Electrical tape
• Scissors
A
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INSTRUCTIONS
1. Take a balloon and stretch it
lengthwise a few times to make
it easier to inflate. Then blow
it up almost all the way with
the pump. Leave about 4 to 5
inches uninflated at the tip (the
end of the balloon). When you
take the pump off, let out a little
air. This is called “burping” the
balloon, and makes it easier
to twist it. Tie a knot in the
neck to seal it. Repeat with the
second balloon
(Figure
A
)
.
2. Take one of the balloons and
pinch it gently about 3 inches (8
cm) from the knot. Twist it around
three times. Do the same to
the other balloon, then connect
the two balloons by twisting
them together where they are
already twisted
(Figure
B
)
.
3. To make the elbow, bend one of
the balloons in half
(Figure
C
)
. At
the bend, pinch a golf-ball-sized
section in your fingers. Twist it
around three times, spinning it
like a dial. Then circle it around
the balloon itself until it reaches
its starting point
(Figure
D
)
. Do
the same with the second
balloon.
B
C
D
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E
F
22
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4. Tie the tips of the balloons together using the uninflated extra rubber.
Tie another knot about half an inch (1 cm) above the first. The balloons
will form a diamond shape with hinges in the middle.
5. Now take the vinyl tubing and cut a piece 10 inches (25 cm) long. To
make a release valve, take the scissors and cut a small slit about
halfway down. Don’t let it go more than part way around. When you
bend the tubing back, the slit will open to let air out. To make a seal you
can open and close, cover the slit with a short piece of electrical tape
(Figure
E
)
. If you fold over a tiny bit of the tape at one end and let it stick
to itself, it makes a kind of tab that’s easier to lift when you want to let
the air out. Test the seal by inserting the air pump into the tubing and
making sure no air comes through when it is closed.
6. Poke one end of the tubing through the gap between the two knots in
Step 4. Take a third balloon, inflate it, then let the air out. This is your
air muscle. Pull the opening of the air muscle balloon over the end of
the tubing that pokes out between the knots. The balloon should cover
about 1 inch of the tubing. Secure the balloon to the tubing with a piece
of electrical tape
(Figure
F
)
.
7. Take the top and the bottom of the balloon diamond and press them
together. This is the movement your inflatable hinge will make. Decide
how close you would like them to get, and tie the tip of the air muscle
balloon to the tips of the other two balloons to hold them in this
position.
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8. Insert the end of the air pump into the other end of the clear tubing, as
far as it will go. Secure it with more electrical tape if needed
(Figure
G
)
.
9. To test your design, use the
pump to slowly and carefully
inflate the muscle balloon
(Figure
H
)
. As it fills with air, it
should lengthen and push the
balloon hinge open. To let the
hinge close up again, open the
release valve by unwinding the
tape enough to expose the slit,
and bending the tubing back
to widen the opening. The air
should escape and the balloon
should return to roughly the
same length as when it started.
G
H
Cover Page “i”
Preface Intro Chap 1
Xxxxxx Chap 3
Chap 3 Chap 5 Chapter 2
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