Moritz Grossmann ATUM

After the successful launch of their first collection – BENU (2011), Moritz Grossmann Manufacture now introduces – ATUM, their second line of watch collections. Named after the Egyptian god of creation, this manual winding timepiece epitomizes mature technology and the ultimate in manufacturing perfection.

The superb functionality of the ATUM is reflected in its subtly balanced aesthetic appeal. The movement is embedded in a three part precious metal case with a slender bezel. The applied markers with polished chamfers clearly contrast against the solid silver dial. The subsidiary seconds dial above the 6 is recessed, so that the hands can hover tightly over the crispy defined minute scale.

The hands are manually fashioned in the manufacture and are endowed with a lance shape as well as broad chamfer to match the three-dimensionality of the hour markers. Each hand is meticulously tampered and ground to achieve a sharp, elongated tip.

The colour of the hands is chosen in the interest of maximum contrast against the base colour of the dial; Shiny stainless steel hands match the dark dials while flame annealed steel hands are the perfect complement for all brighter dials. Brown, an unusual colour for steel, is the result of a carefully timed annealing process that needs to be stopped with one second accuracy.

Introduced in 2013, the ATUM stands out with some additional breakthroughs that refine user friendliness and functional reliability.

  • The newly designed oscillator – the Grossmann balance – is crafted in house in its entirety.
  • The Grossmann winder with pusher features an enhanced hand-setting mechanism
  • The re-modified Glashütte stop work supports the flexible arrangement of the parts.

Optimized for artisanal manufacturing techniques, the ingenious design of the Grossmann balance improves the adjustability of inertia and achieves high kinetic energy combined with minimized air resistance and the smallest possible mass. The number of screws in the balance wheel rim was minimized, and the bores in the rim are equidistant. This makes its possible to vary the moment of inertia by inserting mass screws with different head lengths in the bores.

The smooth cylindrical balance staff is integrated in the hub and can easily be replaced if necessary. The Grossmann balance interacts with a Nivarox 1 balance spring which is overcoiled with a quarter arc on the inside and secured to the slotted roller with a brass pin.

The watchmakers at Grossmann addressed the requirements imposed on a manually wound watch by focusing on improved convenience and greater functional reliability.

The Grossman winder with pusher features a refined hand setting mechanism that eliminates two possible error sources: the ingress of particles in the case while the hands are being set and the unintentional alteration of the hand while the crown is being pushed home again. When the user briefly pulls the winding crown out, this mechanism switches to the hand setting mode and stops the movement. The crown immediately returns to its home position but can be turned to precisely set the hands. Afterwards, the movement is restarted with the pusher adjacent to the winding crown without altering the positions of the hands. At the same time, this switches the mechanism back to the winding mode.

A modified Glashütte stop-work secures the tension of the mainspring. After winding, it allows the ratchet wheel to reverse somewhat and slightly relax the mainspring.

The ATUM is being launched in rose and white gold versions with Argenté or charcoal dials.

The following ATUM models are available

  • ATUM rose gold, Ref 002.B211-11-1 Argenté dial, Price: EUR 24,300
  • ATUM white gold, Ref 002.B221-11-1 Argenté dial, Price: EUR 25,300
  • ATUM white gold, Ref 002.B221-13-1 charcoal dial, Price: EUR 25,300

Technical details
Movement
Manufacture calibre 100.1, manually wound, adjusted in five positions
No. of parts: 198
No. of jewels: 20 jewels, 3 of which in screwed gold chatons
Movement dimensions: Diameter: 36.4 mm, height: 5.0 mm
Escapement: Lever escapement
Oscillator: Shock-absorbed Grossmann balance with 4 inertia and 2 poising screws, Nivarox 1 balance spring with No. 80 Breguet terminal curve, Gerstenberger geometry
Balance: Diameter 14.2 mm, frequency 18,000 semi-oscillations per hour
Power reserve: 42 hours when fully wound

Special features
Grossmann balance; lateral pusher for disabling the handsetting mode and
starting the movement; space saving and modified Glashütte stopwork with backlash; adjustment with Grossmann micrometer screw on a cantilevered balance cock; Pillar movement with 2/3 plate and frame pillars in untreated German silver, 2/3 plate, balance cock and escape-wheel cock hand-engraved; broad horizontal Glashütte ribbing, 3 -band snailing on the ratchet wheel, raised gold chatons with pan-head screws; separately removable clutch winder; stop seconds for handsetting

Operating elements
Crown in 750/000 gold to wind the watch and set the time, pusher in 750/000  gold to start the movement

Functions
Hours and minutes, subsidiary seconds with stop seconds

Case, dial & strap
Three-part, precious metal
Case dimensions: Diameter: 41.0 mm, height: 11.35 mm
Dial:  Solid silver, hour markers in solid silver.
Hands: Hand-crafted, steel or stainless steel
Crystal/display back: Sapphire crystal, antireflection-coated on one side
Strap: Hand-stitched alligator strap with butterfly clasp in precious metal

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