CHAPTER 24 ■ BODY BUILDINGDon’t forget that one of the most significant benefits of all washers is to spread the forces and load
across more of the surface. Appropriately, the switch has two washers (keyway washer and lock washer)
sandwiching the plastic container between two nuts.
Installing the 9 V Battery Holder
Sandwich holds its battery with a preformed metal clip (Mouser 534-080 or 534-095). Add some masking
tape to the ends of the clip to prevent the sharp metal edges from scratching the battery.
With a washer on the outside, install the battery clip inside the robot’s body between the power switch
and line-following switch (see Figure 24-25). You’ll need to drill a hole for the screw.
Figure 24-24. Line-following switch installed. Inside the container: switch body, nut, keyway washer. Outside
the container: lock washer, nut, and switch toggle actuator
Figure 24-25. 9 V bracket battery holder with taped tips
Adding the Circuit Board
On the recommended breadboard, there are four holes to attach the line-following circuit board to the
robot’s body. At the beginning of this chapter, you marked and drilled holes for the mounting screws.
Circuit Board Mounting Hardware
To hold the circuit board onto the robot’s body, you’ll need:
- Four #4-40 1½-inch long machine screws (available at local hardware store)
- Four #4-40 nuts with built-in lock washers (available at local hardware store). Plain
#4-40 nuts with separate lock washers are also acceptable