Well, folks, I thought I would mark the season on a more
personal note than usual. I wanted to share with you a small Christmas present
I got for myself. This is the motor unit from the cheapest ceiling fan available
from Home Depot… $25 USD. I bought this because I am toying with the idea of
building a working scale model of the SMART PRT platform. This is something
that has been in the back of my mind for a while, but I have always been
thinking small – like 1/8th scale. That degree of miniaturization,
however, gives little leeway, dimension-wise, and so requires a lot of specialty
parts and machine shop work. As I was browsing the internet, looking for useful
robot parts, I noticed that most of the affordable components were of a size more
suitable for a quarter-scale model. It turns out that if you want to build something
like this a good size is the dimensions of a battlebot. The downside is that
any track layout won’t be something you can put in the spare bedroom! Nonetheless,
I started looking for hub motors that would fit in a 6” wheel. Unfortunately
even the ones for bicycle conversion seem to be too big, and not exactly what I
would want anyway. I was, however, reminded of various Youtube videos which explain
how to make little wind generators out of ceiling fan motors by placing rare
earth magnets around the inside of the casing. This is, in essence, also a brushless
DC hub motor, and if you rewire the coil leads, it could be given the
characteristics of a multi-polar stepper or servo motor. This motor happens to
be exactly one quarter scale, if you add a little rubber around the outside for
traction.
Anyway, the idea appeals to me, and so I am exploring what
it would take… even though the last thing I need is a new project. I have too
many ongoing ones already! I must confess, though, that I have drawers full of
electromechanical junk that I would like to find a use for and robotics has
become an increasingly affordable hobby and one I have always wanted to dabble
in. Also, maybe the robotics aspect of
this project is something that would attract a whole new crowd. After all, the
swing-arm aspect of the design is not all that different from the standard three-axis
articulating arm that is standard on industrial robots. There are high school kids
making these things nowadays. It can be even be done with Legos.
This is what the motor looks like inside, with the outer
inductive ring removed. (The ring pulls the outer case around.) Actually there
is quite a lot of space.
Well, I’m not going to rush out and buy the other three fans
quite yet. With stuff like this I need to hold off a bit, dip my toes in, and
make sure I’m really up for it, or it will just become more junk for my
collection. But I really had to at least pop one of these things open to see
for myself, and, after all, it IS Christmas… Happy holidays!
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