Page 82 - 15 Dangerously Mad Projects for the Evil Genius

Chapter 5 ■ Balloon-Popping Laser Gun 61

WARNING! center. Also, put the board into the can, and make
sure everything fits and that the arm has enough
Some perforated board is made of fiberglass, so room for its complete travel, before gluing the
wear a mask and safety goggles when drilling it
motor into place (Figures 5-21 and 5-22).
because fiberglass is not a good thing to have in
your lungs. Before we add the electronics, we need to test
the motor to make sure everything we have done
Be careful when drilling the perforated board, so far works. We also need to work out the polarity
because it is easy to break if the drill “digs in” to of the motor so we know which terminal goes to
one of the perforations. Choose a drill bit that is positive and which to negative.
just slightly smaller than the diameter of the self-
After putting the arm in its resting position, take
tapping screw.
your 9V battery and very briefly touch the contacts
Once the screw is in place, find just the right to the motor contacts. If it flies up to the top
place for the motor to fit so the nail hits it dead

Figure 5-21 The motor attached to the board Figure 5-22 The motor attached to the board
in the “up” position in the “down” position