Humanoids have fascinated me for many years, and I suppose that would also
include the majority of the world population, as well. Honda’s Asimo got my
attention, but the Robo-One competitions really got me hooked. Watching
them fight each other on the Internet only escalated my passion. My interest
in humanoids has grown into an obsession ever since.
I’m known for being quite the robot fanatic, to the
point it drives everybody I know crazy. Let’s face it, the
robot community is young and has everywhere to grow,
and since robotics is all about efficiency, knowledge and
experience must be passed on to others — which only
makes this hobby flourish. Therefore, I am here to impart
my knowledge and passion upon you, so hopefully this
article will help spark your imagination.
Hands Versus Grippers
I’ve made a few grippers for my robots, and they have
been very effective. Although grippers are fairly easy to
make — and they have their place in robotics as a whole —
they’re just not as cool as digits. Grippers have no real
personality, and they’re kind of plain. I mean no offense to
those of you who have grippers on your bots. Like I said,
I’ve made many a gripper, but I want to step it up a notch.
Hands have got to be one of the hardest features to
duplicate. With so many joints and tiny parts, anybody in
their right mind would quickly give up, especially if you
don’t have a visual of a good hand design. Also, being able
to implement a power source to cause the fingers to grip
and keep the bulk of your design to a minimum is a
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challenge. Our hobby deals with small parts, but we’re not
clock makers! Once you master the art of hand making,
your robot hobby will soar to a whole new level. In fighting
competitions, nothing says “awesome robot” like having
your robot ball its fist for that knock-out punch! Plus, hands
help give a humanoid more personality. Let’s get started!
Gathering Our Materials
The perfect place to gather up the materials for this
project, is the local hardware store. Trust me, this type of
store is definitely the place to go to find inspiration for new
ideas and/or to improve existing ones. That’s how I came
up with this design for my hands. Everything I needed was
right there in the store.
Start in the nuts and bolts section, even plastic nuts
and bolts. My store had plastic washers that were 3/8”
thick, 1-1/4” in diameter, with a 3/8” hole in the middle
(Figure 1). I thought this hole was going to be a problem,
but it actually worked out perfect. (More on that in a bit.)
This plastic washer served as the palm of the hand.
Next, I needed something for the digits. Something
flexible, but something that could hold its own and return
straight. I found some clear, flexible 3/16” OD tubing on a
spool that was sold by the foot. I got three feet of it, which
was way more than I needed, but at a dollar a foot I
couldn’t go wrong. So, now I had the fingers.
My next concern was what to use to pull the fingers
with. I must have walked around that store for 30 minutes,
trying to figure out what to use. A store employee asked if I
needed any help, so I told him, “I need something to pull
the fingers in ... something lightweight but strong.” I didn’t
figure he could help me (and was going to dismiss any
answer he came up with) but then he says, “what about
fishing line?” You could have knocked me over with a
feather. Why didn’t I think of that! Needless to say, I
thanked him a lot and picked up a spool of 6 lb fishing line
(it was the only strength they had) for just a couple bucks.
You could use a higher rated monofilament if you want.
(You could even cut some off of your fishing pole.) Lesson
learned: Never, ever underestimate someone else’s ideas,
no matter who they are.
The little black items you see in Figure 1, are little
plastic sleeves that go on the ends of bolts — another
suggestion my newfound hardware store friend came up
with, now that he knew what I was doing. These will serve
as the finger tips.
Most hardware stores will carry products from K&S
Metal for hobbyists. One sheet of .032” thick aluminum will
work just fine. They come in 6” x 12” sheets. I got my
aluminum from a scrap metal yard. You’d be surprised what
you can find at these places. Like, they say, “one man’s