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Creating a crank operated switch that you can keep spinning indefinitely. Answered

The idea is to have a rotary switch connected to a crank so that when the switch is turned on you can keep on spinning the crank and it won't utterly destroy the switch, also you could do the same backwards, spinning the crank in the other direction so the switch turns off, but you can keep spinning it without it damaging the switch. I can't really find a simple way to do it though, since I'm very inexperienced.

Additionally, I would love suggestions to make the crank feel "heavier", like those emergency crank flash lights.

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rickharris

Best Answer 3 years ago

In the context of what you have described you have a problem - Illustrated below. - Once the cam has turned on the switch so it can go past the switch must mover out of the way.

Then if you reverse the Cam it won't touch the switch to turn it off again.

You can get round this by making the striker flexible so it flicks past the switch every revolution and then on reversal is stiff enough to activate the switch in the other direction and then flick past it again.

BUT this will make a noise every time the striker passes the switch. Perhaps that won't matter.

Possibly an elastic band could be attached to allow a flexible connection as below. turn one way to switch on the other way turns off. it will also make your crank fell stiffer.

switch.jpgcrank switch.jpg
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Dokramuhrickharris

Answer 3 years ago

This is really interesting. Another thing I could try is just have the crank go one way, and have another button to reset the switch to the off setting. Thank you!

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Jack A Lopez

3 years ago

I do not yet have a good picture of this. How many states does the switch have? Is it two, just on and off?

Is it supposed to require more than one turn of the crank to turn the change the switch state?

For example suppose the switch is off. Then 10 turns of clockwise crank rotation turns it on, and stays on. Then any real number of turns of clockwise rotation, like 1 more, 10 more, 1000 more, do nothing.

Then, from the switch on state, 10 turns of counterclockwise rotation, turns the switch off, and it stays off. Moreover, more counterclockwise turns, 1, 10, 1000 more counterclockwise turns do nothing.

I mean for this uh... crank operated switch, I am imagining something like a leadscrew,

https://en.wikipedia.org/wiki/Leadscrew

with a nut that rides on the screw, basically on a line, backwards or forwards, and the nut actuates the slide switch, somehow. E.g. a roller that rolls over a microswitch,

https://en.wikipedia.org/wiki/Miniature_snap-actio...

Also there is some sort of provision at the ends of the leadscrew for to stop the nut from travelling (like grinding off the threads on the ends), and also there is some provision to keep the nut from falling off the leadscrew (like maybe some springs or something)

The really crazy part of this fantasy, is I am imagining the leadscrew could be made from ordinary, hardware store, bolt stock, like 1/4 inch by 20 tpi. Or maybe smaller bolt could be used, like machine screw stock, if you needed it to be smaller for some reason.

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Josehf Murchison

3 years ago

Ok the crank in an emergency light does not just feel heavy it is heavy.

That crank goes large gear to small gear magnifying the drag and increasing the speed of the spinning generator.

So I suppose you could do the same for a rotary switch.

Just Google "infinite rotary switch" there are thousands to choose from.

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steveastrouk

3 years ago

You could do it electronically, using a magnet on your crank, and two hall-effect switches. The two switches get connected to a flip-flop chip, on the set and reset pins

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Downunder35m

3 years ago

Are you old enough to drive a car?
If so, chance are you already have what you need.
The switch in the distributor of an older petrol engine does exactly that.
Also to be found in many lawn movers and other small engines.