Seeking clicking mechanism or design...

November 21, 2009 8:21 AM

What kind of small toys or devices click when you rotate them forwards and backwards? Seeking mechanism or design...

I’m trying to help a friend design a small toy and she needs a mechanism that will click in very small increments as she rotates a small (1 inch diameter) dial that turns 360 degrees on its axis. She needs the dial to click precisely as it turns clockwise and counterclockwise in smallish increments. I was thinking a fishing reel mechanism might work, but that just allows turning in one direction. Then I thought a ratchet wrench mechanism might work, but that also turns in just one direction (and I’m not sure how the inside of a ratchet wrench works either). Can anyone think of existing toys or devices that have a clicking mechanism that freely rotate? Novel solutions? Suggestions? Thank you!

posted by pallen123 to Technology (13 answers total)

Have you considered having two ratchet wrench mechanisms in there? Have them facing each other so 1 clicks turning clockwise and the other clicks turning counter clock wise.

Other then rigging up something in that fashion, I'm having the same problem as you and can only think of things that would work in one direction and not the other.
posted by theichibun at 8:28 AM on November 21, 2009

A ratchet only turns in one direction because of the way the teeth and the pawl interact. What she really wants is the mechanism used in a grogger where the pawl doesn't interact deeply with the gear and is flexible enough to allow it to click from tooth to tooth as you rotated it.

Any old gear and something flexible to ride from tooth to tooth should do for your friend. Or you can use a spring behind a ball bearing as a kind of ball catch to ride from tooth to tooth depending on the durability you're going for.
posted by Kid Charlemagne at 8:31 AM on November 21, 2009

Hmm. I thought "combination lock" but now I'm second-guessing myself. It ticks incrementally, and is bidirectional...
posted by mumkin at 8:46 AM on November 21, 2009

The orange and green knobs in the lower corners of this adorable toy turn easily in both directions and click as they go. You could buy one and take it apart.
posted by drdanger at 9:05 AM on November 21, 2009

Fisher price pull toys, most of them up until the plastic ones have a mechanism that clicks.
posted by Gungho at 9:12 AM on November 21, 2009

Oops! The motors in these cars click in very small increments bidirectionally, but they are wind-up and release. You may be able to just use the clicking portion if you take them apart though.
posted by true at 9:13 AM on November 21, 2009

If I were going to do that I'd put a rotary encoder on the wheel, and produce the click with a single chip computer. All the mechanical ways of doing this have considerable amounts of slop.
posted by Chocolate Pickle at 9:33 AM on November 21, 2009

That should have been "an optical rotary encoder".
posted by Chocolate Pickle at 9:35 AM on November 21, 2009

There's a game called HeroClix where the base of each piece rotates and makes a little clicky sound. They're easily acquired at your local comic book or gaming shop. I'm not sure if this is the type of click you're looking for. IANAMEJACBN (i am not a mechanical engineer just a comic book nerd)
posted by mrsshotglass at 10:17 AM on November 21, 2009

She could make a smaller version of the kind of noisemaker I used to use on Purim, which uses a ratchet-like mechanism to make clicks in both clockwise and counterclockwise directions.
posted by sciencegeek at 11:57 AM on November 21, 2009

"Smallish increments": how small do yu mean? (eg, how many degrees per click / how many clicks per revolution?) If the increment is too small for a typical detent mechanism, then maybe a gear reduction and then a detent?

Actually, do you just want the audible click, or do you want the mechanical feel as well?

I think Kid Charlemagne has the easiest idea — a gear or toothed wheel, with either a flexible bit (ala the Purim groggers, whose name I didn't know before) or a little captive ball bearing (I think this is how higher quality detent mechanisms are usually made).
posted by hattifattener at 12:43 PM on November 21, 2009

There are also the New Year's Eve noisemakers where you use a handle to twirl a ratchet contained in a disk ; they work both clockwise and counterclockwise, perhaps via the same mechanism as the Purim groggers.
posted by carmicha at 12:49 PM on November 21, 2009

The scroll wheel on my mouse does that. What kind of increments are we talking about here? 90 degrees? 2 degrees? Does it just need to make a sound? Does it need to be consistent/accurate/repeatable?
posted by kenbennedy at 10:27 AM on November 23, 2009