Omega Caliber 1260

Omega caliber 1260 tuning fork movement from an Electronic F300 Hz wristwatch. Designed by Max Hetzel, this movement began production in 1972.

Although this tuning fork movement was designated by Omega as a caliber 1260, the base movement is an ESA (Ebauches S.A) 9164 found in several other watches from Baume et Mercier, Eterna, Longines, Tissot, etc.

“The Accutron, an electromechanical watch developed by Max Hetzel and manufactured by Bulova beginning in 1960, used a 360 hertz steel tuning fork powered by a battery as its timekeeping element. The fork allowed it to achieve greater accuracy than conventional balance wheel watches. The humming sound of the tuning fork could be heard when the watch was held to the ear.” –wikipedia

The humming sound mentioned in the wikipedia quote above is why these timepieces were often called “hummers” or watches with “hummer movements”.

Spinning Seconds:

The Omega 1260 F300Hz example pictured on this page was filmed before service for demonstration purposes to show viewers what it looks like when a 1260 is in desperate need of an overhaul. It was experiencing the dreaded spinning second hand issue when adjusting the time (you can watch a video of it here (spinning seconds at about the 4:15 timestamp), and learn more about why that happens at: http://omgili.com/newsgroups/alt/horology/grg2n6sr31newsmotzarellaorg.html

Caliber Commentary:

This comment by YouTube user Lukas Vrabec was posted on the video linked above:

“Difference between quartz and turning form movement mechanism: Tuning fork is tuned to 300 Hz and directly runs hands via wheels. – hence that non-stop movement of second hand Quartz crystal gives impulses (usually 32,768 Hz = 2^16) to simple electronic divider making it one pulse per second which is used to drive small stepper motor – hence that one movement per second of second hand.” –source

Another comment did not realize that the video was pre-service:

“That watch needs a service! You’re damaging the index wheel because the clutch is dry and not disengaging. The second hand should not turn when you change the time. The index wheel is very delicate in this movement and you should also never turn the hand backwards to change the time, always forwards.”

“Time Setting Position: Turn the crown in either direction until the desired time is reached.” –source

“Specifically, one should not remove the stem (which is required to uncase the movement) until the oscillator module is removed. The purpose is to protect the index wheel, index finger and pawl finger.

The 1250 (esa 9162/64) does not have a mechanical stop or hack function. The canon pinion function is dependent upon a friction wheel which is not only part of the setting mechanism, but also part of the train. The friction wheel is often no longer correctly lubricated by the time service is performed. As a result, any inadvertent anti-clockwise force is transmitted directly to the index mechanism. The results can be pretty ugly…and even if one does not “curl” the index/pawl fingers, index wheel teeth can be damaged.

Index wheels are increasingly rare and expensive…so you do not want to damage them. These are among the best tuning fork movements designed…but they have their foibles: the friction wheel, the plastic date indicator teeth among the most troublesome. The index system is well designed a guage is included with each movement…if you follow the service manual, you will have the best accuracy of any tf system, excepting the beta 21.”