Servo - August 2015

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 wooden hand.

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. Figure 5.