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332    BUILD ROBOTS WITH LEGS


                                    5-1/2"
                                                         Front/rear
                                                          leg link
                                                                  Figure 27- 15  Linkages are
                                          3-5/8"
                                                                  made from 1/2″ brass strips, cut to
                   3/8"
                                                           Middle  length. The holes on either end are
                   Make 2 of each                         leg link  1/8″. Make two of each length.

                   BUILD THE FRONT/REAR LEG ASSEMBLY
                           Prepare the left front/rear leg assembly using one rear leg and one front leg, plus
                           one long linkage strip. Use 4- 40   3/4″ machine screws, nylon spacers, and 4- 40
                           locking nuts, as shown in Figure 27- 16. Be sure not to overtighten the locking nuts.
                           Repeat for the right front/rear leg assembly. Make this one in mirror image to the
                           first.


                   BUILD THE MIDDLE LEG ASSEMBLY
                           Prepare the middle leg assembly by attaching the legs as shown in Figure 27- 17.
                           Use the middle spar, large round servo hub, short linkage strips, and fasteners as
                           noted. You will need to drill out two of the holes in the servo hub to accommodate
                           the screws. The other end of the linkages connects to the large servo hub. Drill out
                           two holes at the 5 and 7 o’clock positions on the hub, as shown.

                   ASSEMBLE TO COMPLETE THE HEX3BOT

                   Remember the note about the locking nuts. The nuts should not be overtightened on their
                   screws, or the robot may have difficulty in moving. Use a screwdriver and wrench to tighten
                   the nuts so that they just begin to impede free movement. Then back off about 1/8 to 1/4
                   turn.

                     1.  Begin with the servo that operates the middle legs. Attach the servo mount to the
                        underside of the base using a pair of 3/8″   3/8″ miniature L brackets and 4- 40
                        7/16″ machine screws and 4- 40 nuts.


                             4-40 x 3/4"
                            machine screw
                     Linkage strip
                                   1/8" nylon spacers (X2)


                          Washer   Lock nut
                                           Leg                    Figure 27- 16  Side view of the
                                                                  legs and linkages, showing the
                                                                  hardware for assembly. The locking
                                                                  nut should not be so tight that it
                                                                  prevents the linkage from moving
                                                                  freely.









   27-chapter-27.indd   332                                                                     4/21/11   11:52 AM
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