Page 354 - Robot Builder's Bonanza

SCRATCH BUILD OR PARTS KITS 323

Figure 27- 4 A precut and preformed
aluminum X- Y joint, available from a
number of online specialty robotics
retailers.

Plans for the joint parts, which can be constructed using nothing more than hand tools,
appear later in this chapter. These same joints are then used to create a fully functional and
robust six- legged walking robot, which is provided as a free bonus project on the RBB Online
Support site.

BUILD FROM PREMADE PARTS
Numerous sources such as Lynxmotion and Pitsco provide premade parts for X- Y joints.
Prefabbed aluminum brackets like the one in Figure 27- 4 come cut and drilled to work with
most any standard- size servo motor. The bracket weighs about the same as the PVC X- Y joint
(half an ounce), but the PVC version is considerably cheaper to build.

Various types of these aluminum brackets can be combined to create different arrangements.
G For example, you can create an X- Y bracket with an L bracket in order to reconfigure the
orientation of the servo motors used for the joint. Among other things, this can be used to
provide a more streamlined shape or to create mechanisms for 3- DOF joints.

Some kits with premade parts use modular metal and/or plastic construction and are
designed as development systems for building walking and rolling bots. Example: The
Bioloid robot sets offer numerous permutations including sophisticated bipedal designs.
The kits, which are designed for advanced study, are available in different parts assort-
ments.

BUILD FROM A MIXTURE OF PARTS
There’s nothing stopping you from combining your own homemade parts with prefabbed
ones, mixing and matching as needed. For example, you might combine a PVC X- Y joint with
a premade L bracket. You might also provide your own chassis for the robot, leaving just the
leg pieces as store- bought.

MOTOR SHAFT SUPPORT AND YOKE BRACKETS
The simplest of servo brackets, like the one in Figure 27- 3, lack a means to support the load
placed on the servo motor by the weight of the leg pieces. This isn’t a major problem for

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