amount of natural cushioning.
For the palm and forearm sections, I used pine wood,
MDF, and a few sliced up paddle pop sticks.
As far as moving the fingers went, I figured I’d need six
servos: one for each finger and two for the thumb.
To control it, all I wanted was four inputs to give the
hand four different functions, so I opted for a basic control
board PCB (printed circuit board) that would have four
buttons (for the inputs), and would be powered by a
separate 5V power supply for the six servos.
Finally, there was the shiny new Arduino Uno which
would be powered by my laptop.
This collection of bits and ideas all made a lot of sense
and I jumped right into it — exactly what the enthusiastic
tinkerer does on holidays!
I was now ready to build and program the little
Putting It All Together —
Assembly and Soldering
I had the sketches of the finger segments done, so it
was just a matter of marking the dowel and cutting all the
segments. I cut the lower end of each palm-facing segment
at 45 degrees, so the finger could close fully without the
ends of each segment touching and not being able to travel
further (Figure 5).
I needed to cater to the knuckle/hinge, so there would
be a gap of about 10 mm between two facing segments,
Use a drill bit that has a slightly greater width than the
exposed tea infuser shafts, and then drill a hole into each
end of each segment (except the finger tips). This is where
the infuser shafts will go, allowing a small amount of space
for the epoxy. Apply some epoxy to the holes and insert the
shaft into the dowel. Make sure the hinges all line up as
you don’t want to have wonky fingers bending at unusual
angles. Also, be conscious of this placement especially if
using quickset epoxy.
Now, it was time for the cartilage pieces. These need
to be cut the same size as the gap between the finger
segments (approximately 10 mm). Cut a piece of silicon the
same length as the gap, then cut it in half.
You will want to epoxy one end of the silicone to the
top half of one of the finger segments only; you don’t want
to glue the two segments together (Figure 7).
I then stretched the black elastic band pieces across the
top (non-palm facing) of each finger segment, and held
each end in place with rubber bands (you can also use
Figure 6. Hinges cut out from tea infusers
and ready for use.
the 45 degree
angle cuts on
sections so the
• Get a fresh supply of epoxy and super glue.
• Use strong string/thread for the tendons.
• Make sure the servos are mounted tight to the forearm.
• Let the epoxy cure.
• Test the code and servo on their own BEFORE connecting them to a
• Enjoy yourself and learn about mechatronics.
• Let the creative juices flow.
SERVO 08.2015 29