Movement Quality Controls at ONVA

At ONVA, we inspect and adjust each movement by hand for quality and timekeeping. There are multiple points checked before a movement is allowed to be used in one of our watches, and considerable labor may be involved to improve the quality of our movements as they are received from suppliers.

One of these verifications has to do with timing stability and overall precision.

You’ll see here two videos. This is an image of the hairspring in the regulator pins. More about that later, but the thing to notice between each video is how much the spring is moving in between the pins.

•The first video has notably more movement than the second.
•The second video was taken after adjusting the regulating pins— less movement between the pins is preferred.

Why does this matter?

A hairspring has two measurable lengths— the physical length (this is fixed and how the spring is installed, mounted at the stud next to regulator pins and the collet on balance staff) and the functional length (adjustable, how much of the spring is being used to affect the oscillator). The functional length of the hairspring affects how fast or slow the watch will run. The longer the functional length, the slower, the shorter the functional length, the faster.

When the hairspring contacts the regulator pins, the functional length is at those pins, and the rate changes from vibrating at the stud mounting alone. When the spring passes between the two pins, temporarily, the timing changes as the functional length for a few milliseconds is actually the stud for the time the spring is not contacting the regulator pins. This results in significant positional errors as gravity will make the spring passage between the pins much slower in the stem positions.

By closing the regulator pins, the spring has a more consistent vibration point, and the functional length is more regular. It’s important that the spring still has some room to “breathe” between the pins, albeit small, so that the spring is not damaged when moving the regulator pins for more precise timing adjustments.

This will significantly improve the delta (difference between full wind and half wind), and overall rate stability.