30 SERVO 08.2015
small alligator clips). Then, I added a tiny drop of
super glue under the elastic where it met the wood
to hold it in place (Figure 8).
When set, I tested there was the right amount
of flex by opening and closing the finger, and if it
felt right, I applied epoxy resin to the underneath of
each end of the black band, trimming the excess
off each end after the epoxy had set. If it didn’t feel
right, the super glue bond was easily broken,
allowing me to stretch it more or less and apply
super glue again. I used Blu Tack to stick the now
hinged-up finger to the table, while I placed and
glued the elastic.
Now, on to the palm and forearm. I cut the
piece of pine to 300 mm in length which was
plenty for the forearm, then I traced my original palm
sketch onto the piece of MDF and cut it out. Paddle pop
sticks were added to the palm to simulate padding.
After lining up the end of the fingers with the end of
the palm, I marked and drilled holes for the ‘finger-to-palm’
hinge, which was the last exposed hinge (Figure 9).
Again, I used Blu Tack to hold the fingers in place while
applying epoxy to the palm holes and hinge ends.
After completing the palm and the forearm, I attached
them together with a flat piece of steel and moved onto
the thumb connection point on the palm.
I had to figure out how my real thumb actually moved,
Figure 8. All four fingers with elastic resistance strip applied
Figure 7. Tendon guides and cartilage
cushion/stop added. Tip of finger is at left.
Figure 9. Earlier stages. Tracing out the shape of the palm on
a piece of MDF.