need to make tabs on the metal.
Simply set the servo on the
aluminum and mark where the
servo mounts should be (Figure
10). Cut the aluminum along your
lines to make the tabs; mark and
drill the holes. I drill holes about
1/16” smaller than the bolts. The
bolt should tap (making the threads
into the hole) right into the hole, so
you don’t have to use a nut and
washer (Figure 11).
If you’re hot gluing, you need
to make score lines with a knife on
the side of the servo and on the
aluminum where the servo is to go.
Heat the side of the servo and the
aluminum with a heat gun so the
hot glue sticks to the score lines.
Scoring lines into the plastic and the
aluminum gives the glue something
to hang onto and enhances its
gripping ability. If you don’t do this,
things will easily come apart. You
need to heat the aluminum,
otherwise the hot glue will harden
too fast because the aluminum
disperses the heat of the glue so
well. As you can see, I also glued
the forearm servo to the aluminum.
For the fishing line, I used a
round servo horn and added a
thick, round plastic washer to it for
pulling the fingers. I used a round
surface for pulling because it gives
the servo better leverage and can
hold a tight grip with little effort. If
you use a lever horn for pulling, the
servo will have to strain to hold a
grip position — draining precious battery power. Important
note: Make sure you center your servo or position the servo
where you want it before attaching the fishing line or you
might break them. I already made that mistake once!
Conclusion
FIGURE 9.
FIGURE 10.
FIGURE 11.
Hands add a whole new dimension to your robot,
giving it more of a personality. Consider making larger, full
size hands by adding a servo per finger and making a
potentiometer sensor glove so when you move your fingers,
it responds accordingly. You hold the creative possibilities in
the palm of your ... well, you know. SV
SERVO 06.2010 41
