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Chapter 12







                                            Build a Motorized


                                                    Metal Platform



















                        etal offers strength and ruggedness that wood and plastic cannot. While constructing
                   Mrobots out of metal requires more effort (and sharper tools for cutting and drilling), a
                   properly made metallic bot will last years and years and is suitable for both indoor and out-
                   door use.
                     This chapter details the construction of a small but flexible TinBot, using metal for its prin-
                   cipal body parts. Its design uses commonly found hardware, which keeps down its cost and
                   limits the amount of hacking pieces of metal down to the size and shape you want. In fact,
                   construction of the TinBot requires only two cuts through  thin- gauge steel. The cuts are rela-
                   tively easy to make using an ordinary hacksaw.
                   Before you build the TinBot, review Chapter 23 on how to use radio control (R/C) servo motors
                   with your robots. This type of motor cannot be simply attached to a battery to make the bot
           G       operate.
                     R/C motors require a special control signal. In robotics the most common way of providing
                   this control signal is with a microcontroller. These specialty electronic circuits are designed  in-
                   depth in Part 7 of this book.

                   Making the Base


                   Refer to Table 12-1 for a list of parts.
                     Figure 12-1 shows the completed TinBot, which measures 7″   6-1/4″, and stands about
                   2-1/4″ high. It’s powered by two  radio- controlled servo motors. Ordinarily, these kinds of
                   motors operate in a confined arc of about 90° to 180°. But the motors on the TinBot have
                   been modified for continuous rotation, so they function like ordinary gear motors.
                     You can either modify the motors yourself, following instructions provided in Chapter 23,
                   “Using Servo Motors,” or buy them already modified. You can find the already modified ones
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