Eterna Cal. 1466 was one of a family of ultra-thin automatic watch movements produced in the 1960's. This was the basis for the modern ETA 2892.

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

• The base plate of the movement was steeply beveled to make it thinner at the edge than at the center, matching the profile of the Eterna-Matic 3000
• The rotor weight is also stepped so it is thinner at the edge
• All components were placed close together but were kept a practical size for robustness
• The components are arranged around an opening at the center to house the automatic winding mechanism
• The rotor bearing is large and robust, with seven ball bearings rather than the typical five but each reduced in diameter
• The date wheel fits into a recess in the front plate, keeping the thickness the same on date versions

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.

• 18,000 A/h, Eterna-U shock protection
  • Eterna 1455U - (1962-) 12.5 ligne
    • Eterna 1465U - (1962-) date
  • Eterna 1456U - (1962-) 13 ligne
    • Eterna 1457U - (1962-) day, date
    • Eterna 1466U - (1962-) date
• 21,600 A/h, Kif-Ultraflex shock protection
  • Eterna 1500K - (1963-1973) 13 ligne, date
    • Eterna 1500KB - (1963-1973) no seconds hand
    • Eterna 1501K - (1963-1973) day, date
• 28,800 A/h, Kif-Ultraflex shock protection
  • Eterna 1504K - (1973-1975) 13 ligne, date
  • Eterna 1504KB - (1973-1975) no seconds hand, date

• Eterna-Matic 3000
• ETA 2892, the successor movement