Zenith 670

	Brand:	Zenith
	Family:	Zenith Elite
	Height:	3.47 mm
	Jewels:	27
	Reserve:	50 hours
	Frequency:	28,800 A/h
	Winding:	Automatic, Bi-Directional Automatic Winding, Central Rotor Automatic Winding
	Diameter:	25.60 mm (11.5 ligne)
	Complications:	Date, Hacking Seconds, Instant Date Change, Quick Date Correction
	Hands:	Central Hour Hand, Central Minute Hand, Central Seconds Hand, Date Window at 3:00

Distinguishing Technical Characteristics
Central-Rotor Automatic Clockwise Balance Cock Balance at 1:30 Barrel at 7:30 Central Rotor
Production: 1994 – Current
1910s	1920s	1930s	1940s	1950s	1960s	1970s	1980s	1990s	2000s	2010s	2020s

Cal. 670 is an automatic movement from Zenith. It is a compact 25.60 mm movement with date used in Elite models. Unusually for a Zenith Elite movement, it features a central seconds hand. The similar Cal. 680 has small seconds at 9:00.

Some versions place the date window at 3:00, others at 6:00, and still others omit the date window.

Note that Zenith officially lists the height of this movement as 3.47 mm but nearly every other reference specifies 3.28 mm.

Zenith also produced a Cal. 670-S for spherical (domed) dial applications.

The similar Cal. 670 SK uses a silicon escapement and is also available skeletonized.

Hublot HUB1710

Hublot uses Zenith Cal. 670 as their Cal. HUB1710. This is used in various Big Bang models.

Technical Aspects of the Zenith Elite Movement

The basic Elite movement measures 11.5 ligne (25.60 mm) diameter and most models are under 4 mm thick, despite a central automatic winding rotor and date complication. A few models used a larger main plate to move the date window outward or to support complications like a running 24 hour ring. The thinnest Elite movement is the hand-winding Cal. 650 at 2.83 mm and the thickest and most complicated is the large Cal. 687 at 6.20 mm.

Unusually, many Elite movements (apart from the 660 and 670 lines) feature small seconds at 9:00, a distinctive feature that differentiates the watches that use it. Some, however, feature central seconds, an adjustable 24 hour hand, a power reserve indicator, and other complications.

All Elite movements use an annular Glucydur balance wheel with a self-compensating balance spring and fine micrometer screw for adjustment. The automatic winding rotor is mounted on ball bearings like the ETA 2892 and originally included a tungsten carbide element for higher winding power. Most Elite movements boast 50 to 55 hours power reserve and all operate at 28,800 A/h.

Zenith Elite 670: Central Seconds

Cal. 670 was one of the original Elite movements, and remains in production as of 2020. It has central seconds, unlike most Elite movements, and serves as a base for a few complicated versions. Cal. 670 SK, introduced in 2018, is especially notable, as it includes a silicon escapement and is often skeletonized.

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