Build Your Own Combat Robot

116 Build Your Own Combat Robot
FIGURE 6-7
A typical
ANSI #40 chain.
chain-link spacing and subsequent uneven loading on one of the two chains, but
we won’t cover the dynamics and physics of this scenario. This is still an acceptable
method of applying redundancy for safety. When one of the chains fails, you
still have another to carry most of the load. Double-strand roller chain is the best
way to increase load capacity, and the cost of this type of chain is only about twice
that of single-strand chain.
Most supply houses will supply the chain as a random-length loop or as long
pieces of various lengths. Cutting the chain may require that you punch or drill out
the rivet on one part of a link. You can buy a set of chain maintenance tools for
in-the-field chain repairs; these would include a roller chain breaking tool, which
is far easier to use than a hammer and a punch. Also available are chain pin extracting
tools and a unique roller chain puller that allows you to tighten the chain before
inserting a master link connector. For maximum chain strength, a chain can
be custom ordered from the manufacturer in the exact length you need. If you
choose to go this route, you will not need a master link.
The master link is a separately purchased connector link that allows you to create
a continuous loop of chain. You should also buy several extra master link connectors
to fasten the chain together at the length you’ll want. This fastener consists
of a side piece of a link with two pins that fit in the roller parts of the two ends of
the chain, and a figure-8 side piece to fit over the pins on the other side. A clip
snaps over the slotted ends of the pins, locking the master link in place. Figure 6-7
shows a typical chain.
Chain Sprockets
The sprockets used with roller chains look a little bit like gears, but they have more
rounded teeth and are not meant to mesh with each other like a “standard” gear.
For combat robots, you should buy only steel sprockets for their strength. These
sprockets are specified by an ANSI number (sprockets and chains must have the
same ANSI number, or they will not mesh together because the pitch lengths will
not be the same), the number of teeth on the sprocket, and the shaft bore size.
Most sprockets you will find include a keyway to lock them to a shaft with a similar