ETA was one of the three firms “chosen” to develop advanced automatic watch movements by Ebauches SA, thanks in part to their history with Eterna. The chief designer at ETA, Heinrich Stamm, had created many of the company's important watch movements, and was famous for the Eterna-Matic line of watches. For the 1960's, Eterna wanted to develop an ultra-thin successor to their successful Eterna-Matic “Centenaire” line and Stamm took up the challenge.
The result was Cal. 1466 and the related family of movements. Measuring just 3.6 mm high, despite a central rotor winding system, Cal. 1466 made the ultra-thin Eterna-Matic 3000 possible. It was essentially an all-new movement unrelated to the previous Cal. 1438 and contemporary Cal. 1470. This family featured a direct seconds drive, a major modernization, and is much thinner than any previous movement. Common to Stamm's designs, Cal. 1466 features “Eterna” gear tooth profile and un-spring winding ratchet wheels for hand-winding.
The reduced thickness was due to a number of advancements
Maintenance is assisted by the design as well. Just three screws are needed to remove the entire self-winding assembly.
The success of this movement made it the template for the future ETA 2892 family, still one of the most highly-regarded automatic watch movements today.
All movements in this family are 3.6 mm thick, including the date models. The day/date Cal. 1457 is 4.15 mm thick. All have 21 jewels and a power reserve of 44 hours.
This movement family includes both 12.5 ligne and 13 ligne variants. Both are very similar, apart from the base plate size.
Movements were made with “Eterna-U” shock protection (denoted with the letter “U” after the movement number) or Kif Ultraflex (denoted by “K”).
Cal. 1455, 1456, 1457, 1465, and 1466 operate at 18,000 A/h, while Cal. 1500 and 1501 operate at 21,600 A/h and Cal. 1504 operates at 28,800 A/h.
Cal. 1466 is the most famous of a family of movements.