Small parts: Does this exist premade and what is it called?

July 17, 2017 6:14 AM

Basically take a wheel (flat or with a groove down the middle) and glue two of the same gear or sprocket to either side, so that the gears line up with each other and the teeth stick out completely past the wheel. Or take a really thick gear and cut a grove around the middle of the circumference, deeper than the teeth. What would this thing be called?
posted by anaelith to Grab Bag (8 answers total)

I think you may be describing something similar to a key/keyway/keyed joint, which if not exactly what you're looking for, may help with finding additional keywords/descriptions.
posted by bindr at 7:02 AM on July 17, 2017

What is the groove for?
posted by Bruce H. at 7:05 AM on July 17, 2017

These guys seem to have examples of what you mean in the lower right of the picture. Perhaps ask them?
posted by dowcrag at 7:10 AM on July 17, 2017

Best answer: If the teeth are gear teeth, the usual reason to have a groove down the middle is to allow easy cutting of paired sets of helical teeth with opposite handedness. That's a double helical gear, and it works like a herringbone gear but needs less specialized tooling to make.

If they're sprocket teeth, that would be a ganged sprocket or double single sprocket.
posted by flabdablet at 7:21 AM on July 17, 2017 [3 favorites]

Best answer: aka duplex sprocket.
posted by flabdablet at 8:30 AM on July 17, 2017

Are you trying to transition from gear to belt drive? If you describe the application it may help with identifying the correct part you described or an alternate approach.
posted by no1hatchling at 11:02 AM on July 17, 2017

Reminds me of the pulley gear assemblies from old VCRs.
posted by tilde at 4:47 PM on July 18, 2017

Response by poster: Haha, OK, here is my application for this: I want to make some spiffy counters for boardgames. Basically bead on elastic, the elastic goes around in the groove and holds the bead snug, the teeth keep the bead from moving accidentally, and if you use large enough parts it should be easy to operate. Sharpie on some numbers and Bjorn Stronginthearm's your uncle. Could even put two beads, one for current stat and one for maximum stat for games where that changes.

I know I can diy this, but thought I'd check for something pre-made.
posted by anaelith at 3:33 AM on July 20, 2017