Silent DC Motor for Automatic Watch Winder | Feasibility Study Stage

[sophiecentaur]

TL;DR Summary

Our house is very quiet at night and I want to build a silent winder for my automatic watch.

At night, the house is totally silent and I want to make a silent winder to keep my automatic watch topped up. At the moment, our clock radio makes a disturbing whine all night and it disturbs us (real princesses) . I'm in the feasibility study stage.

A winder needs to rotate about 600 times a day and there are a number of ways to obtain that but - silently? I have no experience of playing with stepper motors but I have read that the clicks can be audible. The alternative would be brushed or brushless motors. (I even wondered about a shaded pole AC motor but I guess the hum a lot (worse than the old synchronous electric close motors).
I imagine that a stepper motor could run very slowly and with a low click rate, which could give it a long lifetime in this application. Easy to drive, too.
I expect that some of you will suggest a Raspberry Pi system but there would be much simpler and cheaper solutions - even with a 555 timer and a counter haha. (Plus I haven't yet got into that area off hardware)

It's basically a mechanical project and that aspect will consume a fair few man hours.

 

[Guineafowl]

What is an automatic watch?

Microwave turntable motors are very quiet.

 

[hutchphd]

How much torque do you need?
I made a small rotating centerpiece (1 foot tall) aluminum tree for illumination with a color changing LED as a small homage to my 1960's childhood Christmas memories. (although we always had a pine).
The 1 rpm tree rotation used a standard battery wall clock 1AA cell clock module (Banggood for a buck). There was not a lot of extra torque but it worked remarkably well and silently.

 

[sophiecentaur]

What is an automatic watch?

Wow - you make me feel really old!
Watches used to have springs and you wound the springs every night. Then they invented automatic (self winding) watches, with an off centre weight inside that rotates as your arm moves and keeps the mainspring wound. Pretty much all the classy watches you can buy are of this type. Not as good as quartz for timekeeping; more of a luxury item. If you have more than one then the one you are not wearing needs to be manually wound or put on a machine that rotates it slowly to keep the spring. I have an entry level Tissot 'Visodate' with a crystal window on the back to show the escape wheel and the winder moving around (only novelty value).

The 1 rpm tree rotation used a standard battery wall clock 1AA cell clock module (Banggood for a buck). There was not a lot of extra torque but it worked remarkably well and silently.

I can hear battery clocks clunking audibly at night (real princess stuff). I did consider that approach but I wonder whether the power would be great enough to rotate the watch / bracelet in a vertical plane if the balance were not very good. We have a similar rotating Christmas decoration but you can hear the motor at night.

Microwave turntable motors are very quiet.

That would be difficult to tell with all the other stuff going on in the microwave. lol
EDIT PS I see that those motors are 4W synchronous and I think that would imply a very detectable level of noise.

 

[Guineafowl]

Ah! Don’t worry, I had one of those but it was called a kinetic watch. As I remember, it didn’t matter which way the weight swung.

Microwave turntable motor, cheap, quiet, simple. Make it turn a wrist-sized piece of pipe lagging. You could even put stops in so it auto-reverses. Put it in a soundproof box if you must, but you will habituate to a steady hum better than clicks or steps.

 

[anorlunda]

LOL, the tags for this thread should say "quarantine cabin fever" I doubt that your self-winding watch needs to be rotated 600 times per day. I suspect that 6 or maybe 60 times per day would be adequate. When we wound our watches manually, they would run for a week or more before winding again.

If you have the watch in your possession, you can do the experiment yourself to determine how many times per day it needs to move to stay wound.

Have you seen the solar powered flower toys like in this picture? They sell them in the $1 stores around here. You could strap your watch to that. Since it is solar powered, it only dances in daylight.

 

[hutchphd]

My Christmas tree didn't make no stinkin' noise...but I did have to be careful with the bearings and alignment to make it run well. The motors are really dead quiet (delrin gears)..
So you just lay the watch on a slanted turntable?

Of course I am getting deaf as a stone...

 

[Guineafowl]

That would be difficult to tell with all the other stuff going on in the microwave. lol
EDIT PS I see that those motors are 4W synchronous and I think that would imply a very detectable level of noise.

I have one somewhere - never throw useful stuff away - so I’ll dig it out. I imagine the 4W is nominal and related to starting up with a glass tray and heavy plate of food.

Does the watch have to be in your bedroom?

 

[sophiecentaur]

Ah! Don’t worry, I had one of those but it was called a kinetic watch.

Afaiaa, kinetic watches use a moving weight to charge a battery for a quartz movement. The automatic system is mechanical all the way.

I doubt that your self-winding watch needs to be rotated 600 times per day.

The specs for various automatic watches are all published and they vary between 500 to 800 turns a day. Some figures can be found in this link. Those figures may be surprising but compare it with 20 to 30 turns of the crown (winder button) to wind the mainspring fully with finger pressure.

So you just lay the watch on a slanted turntable?

The watch rotates around the axis of all the wheels inside. See the link above and drool over some of the grossly overpriced watches.

Does the watch have to be in your bedroom?

But of course. It's the last thing I take off at night (after my overalls and workboots!)
This is a novel situation for me. It's usually me, making the clever dick suggestions for solving some other guy's problem. "If I were you, I wouldn't be starting from here etc. etc." I do appreciate the input as I hadn't thought of many of the things mentioned in the thread.

I guess I should just go ahead and buy a few different motors and see which one I fancy the most. The clicks from the stepper would / could be at a very slow rate with no gearing and I would need to do the test over night. Also the motor could be deep inside a heavy case for insulation.

 

[Tom.G]

Ahh... Just make something that works and throw a pillow over it!

 

[sysprog]

My early '70s cheap self-winding Timex watch still works perfectly and was never noisy. Maybe I could have put it the dryer to wind it, but that wouldn't be close to silent. I sometimes wound it by hand just in case.

 

[sophiecentaur]

My early '70s cheap self-winding Timex watch still works perfectly and was never noisy.

"Tickaticka Timex" was the jingle for a Timex watches ad. I had a friend who knew about and who mended watches. He told me that cheaper watches have a comparatively loud and slow tick so that the bearing surfaces can be rougher and cheaper (no jewels). Otoh, my Tissot has a very fast tick (the sweep second hand appears to move smoothly) and the balance wheel is almost a blur BUT you can only hear the mechanism with the watch right against your ear. Timekeeping is very consistent because you have a very high Q oscillator (with low losses - little sound).

throw a pillow over it!

That's about it. Most consumer products are a light weight as they can get away with and a 'heavy' box should match the click sounds less to the surroundings.

Of course I am getting deaf as a stone...

Me too. But it's selective. Even with my hearing aids out, I can still hear ridiculous sounds at night.

 

[256bits]

Attach you watch to one of these. to mimic arm movements.


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

 

[256bits]

Even with my hearing aids out, I can still hear ridiculous sounds at night.

Those special hearing aids being let out at night do bark a lot at times.

 

[berkeman]

At the moment, our clock radio makes a disturbing whine all night and it disturbs us (real princesses) .

Would the sound of a bubbling fountain be relaxing? If so, you could make a nice little fountain with a paddlewheel to wind your watch. Quite the discussion piece for your future parties...

 

[anorlunda]

Quite the discussion piece for your future parties...

Wow, you entertain your party guests in the bedroom?

 

[sysprog]

Well, the sound of Professor Donald Knuth's fast fingers on the keyboard might be obscured by the sound of the diapasons, and the pipe organ music might make us forget about his $\TeX$ for a minute . . .

 

[Tom.G]

Wow, you entertain your party guests in the bedroom?

Best entertainment around!