Ceiling Fan Speed Gauge

One deficiency of modern ceiling fans is the fact that it is hard to tell by looking the speed setting at which it is operating. So I came up with this gauge to permit a qualitative measurement of fan speed. It uses a pivoting weight and some basic physics. See the equation in the photos (R is the distance from fan axis to flag axis, g the gravitational constant, and r the distance from flag axis to flag center of mass. The values I used are R = 0.584m, g = 9.81m/s2, and r = 0.1m).

I considered adding tick marks to the circular face of the gauge so RPM could be read directly, but the relationship between flag angle and RPM depends on several factors that will vary for each fan, including but not limited to a) where the flag hangs at rest, and b) how far from the fan hub the gauge is mounted. So instead, I used a strip of paper glued to the gauge and put index marks on it.

Unfortunately, it was harder than I thought to read a gauge zipping past me at several feet per second but as the fan turned the corner I could see the approximate angle of the flag. In theory this gauge could be used for anything rotating about a vertical axis, though.

Besides 20 or so grams of filament, you'll need a couple binder clips and a few coins or washers for weight, and some paper and glue.

---

There's more where this came from! Other fun designs:
[creation binder-clip-bear-trap-improved]
[creation iris-bottle-trap-live-small-game-trap]
[creation aero-prop-helicopter-toy-qfrederick]
[creation helical-high-capacity-battery-magazine-aa-version]