Good Morning Smart People! I'm working on a small project, a ring box. The lid is a leaf shutter, like an old camera. The body is a wood cylinder glued to the outer edge of the shutter. The bottom rotating ring of the iris is glued to a pvc tube which is glued to a wooden bottom cap. By rotating the bottom cap, the pvc tube rotates, which rotates the iris open and closed. That's the easy part.
Simultaneously, I want a plunger to raise and lower inside the pvc tube revealing the ring as the iris opens, and moving it lower inside as the iris closes. I've carved spiral grooves in the pvc tube, and put acrylic rod "ears" on the plunger to fit in those grooves. This facilitates the up and down motion. To keep the plunger from rotating along with the pvc tube, thus not moving up and down on the grooves, I've cut large windows in the pvc tube to allow longer acrylic "ears" on the plunger to reach straight vertical grooves in the stationary body of the box. This keeps the plunger from rotating, but allows for the vertical movement. This all happens in one quarter turn of the bottom cap. It works. Most of the time.
The problem is that the four points of contact on the plunger, two in spiral grooves, and two in vertical grooves are a little loose, so they don't bind, and this allows the plunger to wobble, becoming stuck in the pvc tube half way through the motion.
Am I on the right track, and need some simple tweeks, or is there a better way to make the two motions with the one turning bottom cap? Thanks in advance for your suggestions.
Mike
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