PARTS IS PARTS:
Terminal Bl cks
Made to Order
● by Nick Martin
Read the robot forums and
everyone agrees: Crimp-on ring
terminals and terminal posts are the
most reliable means of making high
current connections. The problem
is there are a limited number of
suitable commercial products and
they are often the wrong size and
shape, or made of brittle materials.
This cookbook of ideas will have
your bot powered up to terminate
opponents instead of dying from
dodgy connections. The ideas
presented will scale up or down
from beetleweight to super heavy
classes and will save you weight and
money. There are many ways to
make the terminal blocks. You can
use anything from a milling machine
down to hand tools; the finish may
be rougher with hand tools, but the
terminals will function just as well.
types of lock washers and will not
vibrate loose — even when you
forget to tighten them up properly
(don’t ask me how I know this!).
What NOT to use: open-ended
terminals might look appealing, but
will often pull loose. Brittle insulators
such as Bakelite will fail under impact
and should not be used. Cheap plier-type crimpers will not give you reliable
connections and are best donated
to someone you secretly hate.
make my terminal blocks. However,
a circular table saw, a band saw, or
even a jigsaw will get the job done.
Materials and
Construction
Cut the plastic stock to size — A
circular table saw or a band saw will
give the best results for this operation. If you are using a circular saw,
a carbide ripping blade works best,
while on a band saw, a wood cutting blade with a lower tooth count is
better than a metal cutting blade.
Cut the plastic down to a
rectangular bar of the size you have
designed; in the demonstration
block, this is 20 x 25 x 60 mm.
Drill and counterbore the
terminal screw holes — Mark out
the locations of the terminal screws
and position the stock in your drill press
securely. Drill the 1/4” hole through
the plastic and without moving the
Design
Rather than designing your bot
around a standard shaped terminal
strip, make a terminal that fits into
your ideal frame design.
Start by asking yourself
how the terminals could
take up less space, how
they could be safer, and
how they could be easier
to use and mount. The
reference design shown in
Figure 1 is just a starting
point and you can add
features such as side
mounting, thru-wall leads,
or extra connections.
Use nylon insert
nuts to keep the ring
connectors locked down.
They outperform all
Use a plastic that is cheap, easily
worked, and not too brittle. The best
plastic for low temperature situations
is UMHW as it is easy to machine and
resists impacts. Nylon 6/6 would also
be a good choice, and Delrin would
be better for high temperature
areas, although it
has lower impact
resistance.
I used a light
milling machine to
FIGURE 2. Milling
the separator.
FIGURE 3. The base
with wire cut-outs.
FIGURE 1. Dimensions of
the basic terminal block.
SERVO 09.2008 33
