MAKE THE
THROWING ARM
Drill a 1⁄8-inch hole through the center
of the long dowel about ¾ inch from the
end [7]. Use the round face of the ham-
mer to shape the large washer into a
cup [8]. Attach the washer to the dowel
(the cup’s rim faces up) using the bolt,
lock washer, and nut [9].ASSEMBLE THE
TORSION SPRING
Fold the nylon cord in half twice; tie
the loose ends with a square knot [10].
Feed the folded cord through the
¼-inch holes [11], leaving ½ inch of
cord on the outside of the frame. Place
a washer over each bundle of cord.
Insert the 5⁄8-inch dowels into the
cord loops [12] ; position the throwing
arm in the middle of the cord.
Rotate the dowels toward the front
of the frame until the arm presses
against the crossbeam [13]. Insert the
1⁄8-inch dowel into the smaller hole.Lower the throwing arm to the
frame and, using marks as a reference,
screw in both the eyebolt and anchor
and the screw eye. Increase the cord’s
tension by turning the dowels forward.
Lower the arm, hook it into position
[14], and remove the dowel locks.
To fire the catapult, load the bucket
with a projectile and carefully push the
anchor hook out of the eyebolt [15].BUILD A CATAPULT78910111266 May/June 2022