Oscillating Desk Fan
Like a number of projects I developed for the Mountain Vista Railroad, it started as a joke. I'd just completed a window fan, when a visiting modeler quipped, "Now you need to make a desk fan." Pause. "That oscillates." He was expecting an acerbic retort, but instead saw me staring off into space and going, "Hmmm..."
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About an hour later, I finished a functional proof-of-concept mechanism (above). Although terribly crude and not expected to be used for anything but testing, it nevertheless spurred me on to Version 2.0 (below).
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Next, I completed the drive mechanism, which involved a micro-gearbox that I modified to obtain two different rotational rates: one for the fan, and one for the oscillation. The oscillation was achieved using a crank and link.
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However, while I was installing the fan in the building, I slipped with a tool and demolished it. Undaunted, I started over, taking the opportunity to make improvements.
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Principle of Operation
Functionally the mechanism is nearly identical to that of the windmill. The key to its operation is a pair of telescoping tubes with a rod at the center. The spin rod spins the blades via a pair of modified watch gears. The spin rod rotates within a length of microtube that's soldered to the frame; at the other end of the swing tube is a crank arrangement that, through a gear reduction and an eccentric, rotates the swing tube back and forth. The swing tube runs through a fixed tube that's attached to the desk. Hopefully this illustration helps clarify that long, rambling description:
New Home
After the Mountain Vista was decommissioned, the fan was transferred to the White River & Northern X, where it lived inside the Stephen A. Greene Fireworks office, after a brief stay in the yard office.
To get it there, I chopped down the base of the law office to a minimal piece of the former desk. This was necessary because the fan and desk were pretty much inseparable.
After I got the fan installed in the layout base under the office structure, I opened up the window beside it, and added a white LED to illuminate it; otherwise the fan would go unnoticed.
In truth, the project wasn't as straightforward a as it appears: the original motor failed, and I had to replace it. Trouble is, I didn't have an exact replacement, so I had to chop away part of the gearbox to install an entirely different micro-gearhead motor.
Here it is seen while it was briefly in the yard office:
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Another New Home
The fan is now located in the well-lit gas station on the Men At Work diorama, and it has a new, more robust mechanism.
