More Watch (Case) Design

[colinh]

I was thinking about shock resistance recently.

 

Would it be possible to design the keyless works so that when the crown is screwed in the winding stem isn't contacting any of the works?

 

Then the entire movement (with or without the dial) could be isolated from the case by rubber/silicone washers etc.

 

It occurs to me that maybe this is what's already done with some watches—I haven't opened enough yet :)

 

 

 

Unrelatedly, I still don't understand what a separate bezel is for (unless it's a rotating one, or for aesthetics, or manufacturing convenience—i.e. a case that can have a diver's bezel or a fixed one). As far as I can tell it just adds another point of weakness.

 

 

 

I'm doing 3D models of a case at the moment. Perhaps I really will stick my lump of bronze in the lathe one day...

[Marc]

The Vostok Amphibia screw down crown does I believe disconnect from the stem when screwed in thus isolating the movement from the case at that point. It does result in a characteristically wobbly crown when not screwed in which has to be held out with light pressure when manually winding the watch. Not enough to pull the stem into the setting position, but just enough to keep the crown engaged with the stem for winding. Apparently this has resulted in new owners reporting a problem with the crown/stem and hand winding as it is unaccustomed behaviour but once you get the hang of it it does work. I believe that this was developed primarily to allow a manual winding movement to be used with a screw down crown by decoupling the crown from the stem once fully wound thus allowing the crown to be further rotated so that it can be screwed onto the case tube, the decoupling of case from movement from a shock protection point of view proving to be an added benefit.

 

Certina also developed a system where the movement was isolated from the case by a thick rubber shock absorber for their DS series of watches, and I believe that others have also dabbled with such a system. I don't know if anyone has combined the two concepts though.

[colinh]

Thanks. That was interesting, especially about the Vostok.

[bobm12]

I can't figure out how the movement can get isolated from the stem when the crown is screwed down. I haven't seen the watches brought out in this thread so maybe that's why. In any case, it seems like a good idea specially when it improves shock protection among other things.

 

I don't know colin, bezels may even be there to protect the crystal I suppose. Do you have anything in mind regarding them for your design?

Edited October 2, 2014 by bobm12

[Marc]

The sneaky bit is that the movement and the stem remain connected.

The decoupling is between the stem and the crown. Since it is the crown that couples to the case (when screwed down), by decoupling the stem from the crown the movement is isolated from the case.

Have a look here for more info.

 

http://forums.watchuseek.com/f54/vostok-amphibia-analysis-design-methodology-491757.html

[bobm12]

Thank you Marc, very interesting link. Now everything is falling in place! :)