Wooden pager rotating machine

    wooden rotating machine
    Wooden pager rotating machine
Back in 1998, I wanted to test how the Blackberry pagers we developed would perform as they are moved sporadically through the local environment. With the pagers receiving at 900 mHz, moving them around by even a few centimeters, or changing the orientation can make a big difference in terms of reception. If you put the pager in one spot for a test, you can never really know if that spot a 'lucky' or 'unlucky' spot. That, and in real life, the device never spends that much time in a fixed location.

Playing with my Fischer-Technik mechano set, I devised a small mechanism that could move and rotate the pager in three axis at once, thus going through a very large range of orientations in a continuous fashion. Such a device would be useful for some of our tests. It would be even better if the device did not in itself interfere with radio waves, so of course, wood was an ideal material. I would have used wood regardless, mind you, but this was an extra reason!

    crown gear
    Crown gear on one side of the machine

I wasn't sure if the wooden gears would actually work when I started (this was the first time I attempted wooden gearing), but as I built more, and tested the parts, it all worked, so I kept at it until I had the finished machine. The whole thing is powered by an AC electric motor, with an a little electromechanical (no electronics) interval switch powered by another motor. There's cams and switches to select continuous motion, or intermittent motion at 12, 60, or 240 second intervals.

    wood machine gears
    The machine parts, drying from varnishing, made for an interesting still life

There is no coupling between the test software and the machine. The idea is for the machine to sufficiently randomize things that any sort of bias in the setup gets averaged out by the many positions that are eventually tried.

The machine does have the flaw that it is not readily portable, and also needs 110 volt electrical power to run. When flying to different parts of the country, taking this machine with me is not a practical option. So I decided to build a much smaller version, powered by one of those super efficient lego motors. Of course, once you start building with legos, might as well build the whole rotating machine out of legos


More on making Wooden gears. Also Check out my Gear template generator

More Wooden machines on my Woodworking website