Ok Rolex watchmaker aficionados - I'm curious about what appears to be a regulator on the balance bridge (see circled photo below) of the calibre 3235.


As a free sprung balance, being a regulator doesn't make sense - at least to me.

Then I thought, maybe its for making micro adjustments to the beat error? While I've always found adjusting the stud on a Rolex movement to be easy and well-design - perhaps Rolex wanted to get watchmaker screwdrivers away from the stud connection for making beat error adjustments.

While considering the regulator and spring stud adjustment I briefly considered this is a mechanism for the regulating nut that controls the balance bridge height. But that was a fleeting consideration - it's one sided and doesn't make intuitive sense to adjust the height from here.

I land on a micro-adjustment mechanism for the spring stud (beat error). But can anyone confirm or deny non-scientific, uneducated guess?

 

I’d like to see the rotor turned away from the balance cock, for a better view. I suspect the screw you refer to is for adjusting endshake of the balance staff. There doesn’t appear to be any connection Of the screw to the moveable stud carrier.

 

@Canuck Here are a couple more pics to help explain the movement. I don't have one on hand so I must rely on web images.

The 3135 has two regulating nuts, one on either side of the balance bridge. It allows for end shake adjustment on both sides. It seems strange that this new movement would only have end shake adjustment on one side of a bridge.

 

It would appear that the “regulating nut” you refer to is concentric with the screw that holds the balance clock in place. I wonder if the screw you are wondering about might have a pinion on the lower end that meshes with the teeth on the regulating nut? If so, then turning the screw adjusts the nut without having to remove the balance wheel and cock? That would be my guess. The calibre 3035 uses a single screw on the balance cock to allow for adjusting endshake. I don’t know why it wouldn’t work on this newer calibre.

 

I think that you're right. The only reason I thought it odd to use one on a bridge is the bridge will rise and lower asymmetrically. As in, one side will go up and down while the other is in a fixed position. I would've assumed a parallel vertical movement would be preferred.

 

The amount of adjustment that might be required to arrive at the correct endshake would not likely exceed 0.01 mm, or little more. I doubt that would be critical.