Page 167 - Robot Builder's Bonanza

136 ASSEMBLY TECHNIQUES

Figure 13-7 Plastic brackets may be
used to secure parts to robot bases, like
this pair of brackets used to secure radio
control servo motors to the underside of
a robot.

• 1″ 3/8″ or 1″ 1/2″ corner angle brackets. Typical uses are for attaching pieces at right
angles to base plates and for securing various components (such as motors) to the robot.

PLASTIC BRACKETS
Metal brackets can add a lot of extra weight to a robot. Plastic brackets add only a little weight
and for small robots are just as good. The bracket is made of a durable plastic, such as
high- density polyethylene (HDPE).
To add strength, the bracket uses molded- in gussets that reinforce the plastic at its critical
stress points. The result is a bracket that is about as strong as a steel bracket but lighter. Figure
13-7 shows a pair of plastic brackets used to secure servo motors in their mounts. The brack-
ets make it easy to assemble and disassemble the parts of the robot.
Alas, plastic gusset brackets are not easy to find. They are available from some furniture-
building outlets, as well as select online resources. See the RBB Online Support site (refer to
Appendix A) for leads. Sizes and styles are fairly limited, but those sizes tend to be quite ade-
quate for most jobs.

Selecting and Using Adhesives

Glues have been around for thousands of years— stuff like tree sap, food gluten, and insect
secretions. Maybe the first Post- it was made with a piece of papyrus soaked in camel spit. You
never know!
Modern glues— more accurately called adhesives— are chemical concoctions designed to
bond two surfaces together. While there are bazillions of adhesives out there, only the ones
available to consumers are covered here. Intentionally left out are the glues that need expen-
sive tools to apply, are very dangerous to use, or are only available in 55- gallon drums.

SETTING AND CURING
All glues bond by going through a number of phases. The main phases are setting (also called
fixturing), then curing. During the first phase, setting, the adhesive transforms from a liquid

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