As described in our webpage re the Development of the Chronomatic Movements, the Caliber 15 movement was developed in order for Heuer (and Breitling) to be able to lower the prices of their automatic watches. So they deleted the hour recorder (and related components of the movement), used a less expensive shock proofing system, etc. [Please see the section of the article, pasted below.]

Despite these changes in the mechanical features of the Cal 15 chronographs, of the quality of most of the materials remained unchanged -- dials, hands, cases, etc. On an aesthetic level, many of today's collectors seem to prefer some of the materials used in the Cal 15 chronographs -- for example, the amazing paint finish on the dial of the 1533G Monaco -- and some of these Cal 15 watches are priced comparably to the Cal 12 versions (in today's market). Compare the gray Cal 12 Monaco and the gray Cal 15 Monaco, and the edge may go to the Cal 15; there is certainly no discount.

So while the Cal 15 was introduced as an economy version of the Cal 12 chronographs, in today's market, I would say that the lines have been blurred, and values are now determined on a model-by-model basis, rather than across the board. Compare a rare and attractive Cal 15 (like the "exotic" Autavia), to a more common Cal 12 (like the "Viceroy" Autavia), and the Cal 15 may be the winner, in today's market.

Bottom Line: If you like the looks of a particular Cal 15 chronograph, and can live without the hour recorder, then you should not hesitate to add it to your collection. They are no longer the "poor relatives" of the Cal 12s, and are highly collectible.

Jeff

The Caliber 15 Movement

In order to be able to offer their automatic chronographs at lower prices, in 1972 Heuer and Breitling modified the Caliber 12 movement so that it was offered as the Caliber 15 movement. The most obvious difference between the two movements is that the Caliber 12 movement has a 12-hour recorder and a 30-minute recorder, whereas the Caliber 15 movement has only the 30-minute recorder. [mention re running seconds at ten o'clock] In addition to the deletion of the 12-hour recorder -- which saved considerably in the cost of parts and labor -- the following changes from the Caliber 12 to the Caliber 15 allowed the Caliber 15 to be produced on a more economical basis:

Brass Balance Wheel (rather than Glucydur). The Caliber 12 movement used a Glucydur balance, while the Caliber 15 movements used a brass balance. Glucydur is an tradename for an alloy made of berrylium, copper and iron. This material features excellent hardness and high stability over a range of temperatures, and is resistant to deformation or damage.

KIF Shock Protection (rather than Incabloc). The Caliber 12 movement used the Incabloc shock protection system, whereas the Caliber 15 movement used the KIF system. The primary difference between the Incabloc and KIF shock protection systems is in the shape of the spring which holds the cap jewel in place; both springs are hinged so that the jewel can be removed without removing the spring.

Deletion of Isochron Regulation (Micro-Regulation). The Caliber 12 movement used the Isochron micro regulation system, which derived from the regulation system used in the Buren Intramatics. The Isochron system uses two sets of eccentric screws and forked levers to move the regulator (307/1) and the hairspring stud (364) with great accuracy. This system allows the adjuster to put the watch into near perfect beat and regulation without many frustrating back and forth movements of the regulator (curb pins) and stud carrier. This regulation system is not used on the Caliber 15 movement, making it more difficult for the watchmaker to regulate the watch accurately.

The use of the Caliber 15 movement rather than the Caliber 12 movement allowed a Caliber 15 Carrera to have a retail price of $170 (versus $185 for the Caliber 12 model); the Cal 15 Autavias were priced at $185 (versus $200); and the newly-introduced Calculator retailed for $200 with the Caliber 15 (versus $220 for the Caliber 12 model).

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: I've been searching around this forum and the net, and I can barely
: find any info on the Autavia 15630? Is there some reason for
: this (is it just very rare)?

: Also, is the Cal 15 as desirable as the Cal 11 or 12?

: Thanks for the help!