junk, is another man’s ... robot.”
You’re also going to need a servo for the hand. The
servo doesn’t have to be a powerhouse; it just needs at
least 45 oz/in of torque, which is what I’m using. Currently,
it is the TS- 53 standard servo from Tower Hobbies.
Besides being a robot fanatic, I’m also hot glue junkie. I
use it for everything ... well, almost everything. I live in the
northern part of the US where the temperatures are not
that hot all the time, so using hot glue for keeping things
together is not an issue. For those of you who live in
warmer regions, you might want to use either a high
temperature hot glue stick or go with epoxy. When it gets
too hot — say around 90 degrees — the glue will get soft
and eventually cause your creation to fall apart. I’ll show
you a little technique I do to keep things together a little
longer, in a moment. A nut and bolt alternative is more
durable, but using this method can add extra weight to
I call this section finger food because this is where your
cutting skills will be used. Extreme care must be taken here.
Let’s begin work on one hand. In Figure 2, I’m cutting the
tubing into 30 mm lengths. I usually work in millimeters for
simplicity and accuracy’s sake. Three fingers and a thumb
should be enough for grabbing things, so you need to cut
four pieces. If you decide to make the fingers longer or go
with an extra finger, it will be harder for the servo to pull
the extra resistance — so get a stronger servo to do this.
I’ve found that too long of a finger looks creepy and
adding an extra finger is really unnecessary.
Next, we need to cut “v” notches in the
tubing. Like human fingers, there are three joints
per finger which means we need to pain-stakingly
cut three notches into each tube finger. Please be
careful! Take your time with this part. Make sure
that you cut the v notch pretty wide, in fact, the
wider the better. A wider notch makes it easier for
the finger to bend. Also, make sure that your cut
goes all the way to the bottom of the tube.
You’re probably wondering why we even
need the notches. The notches give the finger a
“direction” to move. If you do not cut these, your
finger will just bend willy-nilly in any direction.
There is also much more resistance to make the
finger bend. Another thing to keep in mind is to
make sure your notches are in line with one
another. Otherwise, your finger is going to bend
in different directions (Figure 3). It’s easy to
misalign the cuts when you’re working with
something so small, so take your time.
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