Maybe a dumb question but I came across one of those seikos that's you can't hand wind and that got me thinking. How many times do you have to rotate one of those till it's fully wound? Is one rotor rotation the same a one crown rotation? Would how much wind a rotor rotation provides vary from brand to brand, movement to movement?

 

The simple answer is, "No".

If you think about how many times the rotor rotates in the course of a day, it must be thousands of times. To wind an automatic watch manually, it takes anywhere between 40 and 60 turns. Manual wind watches typically take far fewer turns of the crown. I have Zeniths that are fully wound in 10 turns and run for two days.

 

No, rotor would have to be massive to wind 1:1 with crown.

 

Thanks guys.

 

The average automatic takes 50 - 60 turns of the crown to reach a full wind. A rotor might have to make 650 to over 1000 rotations to fully wind a mainspring. Of course, that all depends on the ratio of the gears in the keyless works, and the ratio of the gears in the self winding system.

 

As others have said, the gearing inside automatics is such that rotor revolutions do not equate to crown rotations. In fact, if you turn the crown until you hear a single "click" of the ratchet wheel, you may have rotated the crown 5-10 degrees (guesstimate). It might take 2-3 full rotations of the rotor to wind it the same amount. Also consider some automatics wind in only one direction. Others wind more efficiently, in both directions no matter which way the rotor spins.