DIY
CIRCUITS
The Bobbinator
Make inexpensive linear actuators out of
sewing machine bobbins.
By Andrew Lewis
LINEAR ACTUATORS ARE MOTORS THAT
work in a straight line. They’re very useful for
controlling valves and levers, building robots,
and retrofitting old mechanisms for digital
control. The simplest form of linear actuator
has only 2 positions, while more complicated
actuators can be positioned just like stepper
motors and servos.
I needed 32 linear actuators for my latest
project, and I was shocked to discover how
much they would cost. After a little thought,
I decided that I only needed simple on/off
actuators, and I would try to make them
myself using off-the-shelf parts.
on the sewing machine. Feed the end of the
copper wire into the hole at the top of the
bobbin. I left about 1" of wire sticking out of
the top, so I could solder the coil in place later.
2. Feed the wire through the thread guide
nearest to the bobbin filler. Do not use the
tensioning wheel or the other guides. Place
the spool of wire somewhere that it won’t
snag, and run the sewing machine slowly.
Watch the spool fill with copper wire (Figure
A), and apply gentle tension to the wire with
your hand. Don’t grab the wire tightly, or
you’ll cut yourself.
Wind and Wrap the Bobbin
3. When the bobbin is full, stop the machine.
1. Place an empty bobbin onto the bobbin filler
Hold the wire in place on the bobbin with your
Andrew Lewis
150 Make: makezine.com/29
