Author Topic: Barber Pole  (Read 177 times)

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    • David's Modeling Journey
Barber Pole
« on: September 20, 2020, 06:58:24 AM »
When I decided the smaller of the shops in the Shops II building would be Jim & Glenn's Barber Shop, kitbuilding came to a grinding halt as I spent the better part of a couple of days trying to figure out how I'd make another working barber pole. Although I'd done it twice before (once for the White River & Northern IV, and again in Z Scale on the James River Branch), this time I had a major complicating factor: there was no place to hide the mechanism, since the space was wide open and full of windows. I investigated all sorts of possibilities, including incredibly tiny gear trains and other micro-mechanisms. This would involve the tiniest mechanical parts with which I've ever worked in order to animate the smallest object I've ever made, at a time when my skills were rapidly deteriorating.

My solution turned out to be a very direct approach, in all senses of the word. No gears, no friction drive, no mechanism to speak of; instead, the pole would be spun by a short length of 0.005" stainless steel spring wire attached directly to a geared motor under the sidewalk.

One disadvantage of this approach was that a short length of the drive wire would be visible between the bottom of the pole fixture and the sidewalk; if it was visible enough to be distracting, my plan was to either locate a large potted plant beneath the pole, or pose a figure right under the pole to disguise the wire. Another disadvantage was that it's impossible to illuminate.

But the advantages were much more compelling: for starters, it required no precision assembly and alignment of gears or other mechanism parts; I just needed to drill a few tiny holes. Cosmetic advantages included being able to make an incredibly small pole—a classic 1950s Marvy pole is two feet tall and six inches in diameter, and I could come pretty darned close to that (which is much smaller, in fact, than the Z Scale one I built). Plus, I could mount it on a bracket and have it standing freely away from the wall, as many real ones are.

I started with the bracket. Since it's easier to shape material around holes rather than drill holes precisely within a small shape, I drilled two #76 holes in 0.010" thick plain sheet nickel, cut around it, then did the final shaping with a nail buffer. Incidentally, it took three tries to get a proper bracket.



I was sweating over what to do about the top and bottom caps; I surely couldn't fabricate good-looking parts that small. But after various tiny items from my copious supply of tiny items totally failed to work, I wound up fabricating them from 1/16-inch brass tubing. First, I rounded the edges of the ends, then removed slivers by rolling the tube under a knife, and finally soldered the bits (among the smallest parts I've ever made by hand) to the bracket. The holes filled in with solder, as I expected, but they were easily drilled back out, although I didn't drill all the way through the top cap.


Next, I attached the finished bracket to the window trim part. Naturally I bonded it with CA, but I wasn't convinced such a minuscule bond was strong enough, so I bolted it in place with two Scale Hardware 0.5 UNM hex head bolts and nuts, threaded through #78 drill holes. It not only guaranteed the bracket would never come off, but also looked cool—even though the bolt heads scale out at almost five inches across!


Finally, I tackled the barber pole itself. Based on past experience, this would be the most challenging part, and it still was. Last time I used decals to make the red and blue stripes, but my decals had all decayed. Instead I used thin strips of Scotch "magic" tape colored with Sharpies. I applied the stripes to a 1/16" styrene rod with a #77 hole drilled through the center (I lost count of how many tries this took to get right, but I think it was about a dozen).

After the stripes were in place, I cut a segment out of the rod to fit the bracket. Then I installed the rod on the bracket using a length of 0.018" stainless capillary tube as the bearing shaft.

The pole is rotated with 0.005" spring wire that's painted black, just like the window frame behind it, so the wire virtually disappears. Each end is simply inserted into a capillary tube, one inside the pole, and the other mounted on the end of the geared motor.

Above is a test of the mechanism; below is the permanently-installed mechanism.