The White River and Northern Model Railroad: Clinic

	The N Scale

	Model Railroad

Getting a haircut on the White River and Northern IV

Getting a haircut on the WR&N IV

Yes, this barber pole lights up and rotates! Bear in mind this is N scale: the pole is roughly 1/4-inch tall, which is about as small as I could make it given the materials used. I had considered taking the easy way out and modeling a street-side barber pole, which is usually mounted atop a cast iron stanchion. This would have been far easier to animate; and this is why I chose to model the wall-mounted style instead—I really wanted people scratching their heads trying to figure out how it was done. (It worked.)

Behind the diminutive barber pole is an enormous mechanism—comparatively speaking—which is illustrated in cross-section below. A geared micromotor rotates two shafts that extend into fittings formed at the ends of brass tubes bonded to the edges of a styrene mounting block. The ends of the shafts were tapered slightly so that they could apply a small amount of pressure to the ends of the barber pole; this was accomplished by mounting the rods in a drill chuck and gently filing the ends as they slowly turned. The junkbox yielded a set of three matching gears, and a scrap of thin phosphor bronze was cut to form a retaining spring that would hold the drive rods in place.

Wedged between the tips of the two counter-rotating shafts, the pole itself was made from a length of styrene rod that was carefully drilled lengthwise to form a tube. The spiral stripe was made by masking the tube with a narrow strip of masking tape and painting the exposed area with red stained glass paint. The tube is held in place with two short bits of brass thin-wall tubing soldered sideways into the ends of the main brass tubes.

Assembly was something akin to a puzzle. After creating the two fittings that hold the barber pole, the lower brass tube was bonded to the styrene block mount with CA. One microbulb lead was threaded through the lower microtube; the pole was dropped down over the bulb, and the other bulb lead was threaded through the upper microtube. The upper brass tube was bonded to the styrene mount and the bulb leads were soldered to the brass tubes. The drive rods with gears were inserted, and then the retaining spring was screwed to the styrene mount. The finished assembly pokes through a slot carved in the side of the building, and is removable for maintenance.

The neon sign, which was made by Quality Products of Castro Valley, California (now defunct, I believe), is lit using four blue colored bulbs instead of the single supplied white light. The barber shop interior includes a young customer getting his hair cut in front of a mirror, and a regular microbulb was positioned on the ceiling to shine directly on the figures so they were easily visible; the interior assembly was attached to the mechanism and wired into the same supply. The building is a stock DPM kit.

After all of that work, the building that housed the barber shop wound up located at the back of the WR&N IV! While the layout no longer exists, the barber shop was saved and can be seen on Rick Spano's Sceniced and Undecided, where it belongs—at the front of the layout. By the way, the barber shop resides in one half of a building that also features the video store with chaser light sign, another dynamic lighting effect accomplished with a micro-mechanism.

Making Repairs

Nine years after building the barber pole, the lamp finally burned out, and so one evening I showed up at Rick's armed with a replacement microbulb. Now came a true test of the mechanism's design—after all this time, I wasn't quite sure what I was up against. I knew it was removable, but when I dug into the building's innards, I'd forgotten that I had also used the two mounting screws to pass electrical power to the mechanism, eliminating the need to cut and re-solder wire connections. My life was even easier than I'd anticipated!

The only thing I didn't do that would have made the design ideal was make one of the two brass tubes removable. It would have been simple enough to solder the tube to a small brass plate that screwed onto the styrene block mount, but I imagine I was more concerned about making the mechanism too bulky. The block and tubes were made much longer than what is shown in the illustration so that the gears were set well back from the front wall; this allowed me to create a detailed interior right next to where the barber pole was mounted, further confounding visitors. The interior is part of the removable assembly, and can be seen in the second photo (notice the boy is not sitting in a chair—no need to model what can't be seen).

As it turned out, it wasn't too difficult to break the CA bond between one of the tubes and the mounting block. Once that happened, disassembly, bulb replacement and reassembly went quite quickly and smoothly. I was careful to scrape away the old dried CA from the styrene block so that the tube would return precisely to its original position (the tolerances for parts this small are very tight). In addition to a detailed view of the fittings on the ends of the tubes, the third photo also provides a good idea of how small these parts are.

Retrospect

After successfully replacing the bulb, I pondered improvements that I'd make if I were to start over. The first thing that came to mind was to use one or more LEDs instead of a microbulb. Back when I originally made it, flea-sized surface-mount LEDs were not prevalent; but even now, using LEDs in an application such as this would likely be a bigger challenge than making the microbulb easier to replace. Aside from this, about the only improvement I'd could think of would be to use red and blue decal stripes instead of translucent paint to make the spirals. In fact, I wonder now why I didn't think of this back then; I'd already used decals to great effect for the Mobil Station sign as well as the diagonal stripes on the crossing gate arms...

Lately I've been thinking about taking a crack at a Z scale version. For this, I'd solder tiny metal O-rings to the leads of an axial microbulb to pass current, then enclose everything in a piece of white shrink-wrap. The resulting part should be about the right size, and would be rotated using the same principal as this one. It should make visitors even crazier trying to figure it out!

Image specs: The images were captured with a Canon 20D digital SLR and a 50mm prime lens plus a 36mm extension tube. The exposure was quite long, and since the rotating barber pole produced a blur, a separate exposure of the pole held stationary with my fingertip was digitally inserted into the scene.

See the barber pole in action! | Watch it on YouTube

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