Ultra-thin

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One of the most difficult accomplishments in horology is producing an ultra-thin watch movement.

Background

As with other notable accomplishments, creating an ultra-thin watch movement typically involves serious engineering to overcome difficulties. Perhaps the most difficult aspect of thinness are the questions of durability and structural rigidity. It is critical that movement plates be stiff enough to resist flexing or warping over time, since gears must be precisely located. This is especially true with an ultra-thin movement since these have similarly-thin gears that could un-mesh if they come out of alignment.

Most ultra-thin movements include simpler bridge and cock setups, often with one bridge doing the task of two. This presents serious engineering challenges when combined with the necessity to move gears both vertically and horizontally to make space.

One potential solution to these problems is to combine the movement and case into a single unit. This causes issues with servicing but typically leads to greater structural stability.

Ultra-Thin Movements

Traditional movements are measured in two dimensions: Diameter and height or thickness. Although it would be tempting to trade thickness for width, this is not practical: Some components (notably the balance and escapement and barrel) must have a minimal thickness to be functional. These create a minimum thickness that can be achieved. This is especially true for ultra-thin tourbillons and automatic movements since these components take up quite a bit of room in a movement.

Smallest Volume

Threshold: 300 mm³

  • Watch movement: Citizen G720 (2002) 30 mm² surface area, 73 mm³ volume (5.0 mm x 6.0 mm x 2.5 mm)
  • JLC 101: 228 mm³

Quartz

Threshold: 1.5 mm

Hand-Winding

Threshold: 2.1 mm

Automatic

Micro-Rotor

Threshold: 2.4 mm

Central Rotor

Threshold: 2.5 mm

Date

Threshold: 3.3 mm

Full Calendar

Threshold: 6 mm

Perpetual Calendar

Threshold: 6 mm

Chronograph

Threshold: 5 mm

Automatic Chronograph

Threshold: 6 mm

Minute Repeater

Threshold: 4 mm

Tourbillon

Threshold: 3.5 mm

Automatic Tourbillon

Ultra-Thin Watches

Quartz Integrated Watch

Threshold: 2 mm

Mechanical Integrated Watch

Threshold: 4 mm