MBandF Horological Machine HM9 Flow
Dual Independent Balances with Planetary Differential Kinematics
Technical Deep-Dive Monograph
1. Historical Context & Design Lineage
Founded in 2005 by Maximilian Büsser, MB&F (Maximilian Büsser & Friends) revolutionized the watch industry by treating timepieces as radical three-dimensional kinetic sculptures rather than conventional flat dials. Introduced in 2018, Horological Machine No. 9 (HM9), nicknamed ‘Flow’, was inspired by the aerodynamic streamlined car and aircraft silhouettes of the 1940s and 1950s (such as Norman Bel Geddes’ streamliners and the de Havilland Venom jet).
2. Movement Architecture & Energy Transmission
The HM9 engine required three years of in-house development. Measuring a sculptural 57 mm × 47 mm × 23 mm across 301 components and 44 jewels, the manual-winding movement houses a single high-capacity barrel delivering 45 hours of autonomy. Time is displayed on a vertical speedometer-like dial perpendicular to the wearer’s wrist, allowing effortless reading while driving.
3. Escapement Kinematics & Tribology
The heart of HM9 is its twin resonance architecture: two completely separate, independent balance wheels with screwed poising weights oscillate at a classical cadence of 18,000 vibrations per hour (2.5 Hz) within lateral sapphire blisters. Between the two oscillators sits a central planetary differential—an epicyclic gear train that continuously receives impulses from both balances, mathematically calculates their average rate, and transmits the synthesized, stabilized frequency to the time display train.
4. Metallurgical & Materials Science Analysis
The Grade 5 titanium case is one of the most complex geometric watch cases in history, requiring over 300 hours of milling on multi-axis CNC machines. It features three curved sapphire crystals, including two bulbous pods over the balances and a central canopy over the differential. Because conventional flat O-rings cannot seal three-dimensional organic curves, MB&F patented a proprietary 3D gasket system, achieving a reliable 30-metre water resistance.
5. Chronometric Performance & Testing Standards
By averaging out individual rate variations and positional disturbances between the two balance wheels through the planetary differential, the HM9 demonstrates extraordinary rotational chronometric isochronism.
Calibre Specifications Matrix
| Specification Parameter | Manufacturer & Laboratory Value |
|---|---|
| Calibre | MB&F In-House Proprietary 3D Horological Engine |
| Type | Three-dimensional manual-winding kinetic sculpture |
| Component Count | 301 movement components, 44 functional ruby jewels |
| Frequency | 18,000 vph / 2.5 Hz (Each balance wheel) |
| Power Reserve | 45 hours (Single mainspring barrel) |
| Regulating System | Dual independent balance wheels with central planetary differential averaging rates |
| Case Dimensions | 57 mm length × 47 mm width × 23 mm height |
| Case Metallurgy | Grade 5 Titanium (Aerodynamic streamlined automotive/aviation fuselage) |
| Gasket Innovation | Patented three-dimensional 3D gasket system |
| Water Resistance | 30 metres / 3 ATM |
| Time Display | Vertical dial perpendicular to wrist (driver's instrument display) |
Primary Sources & Citations
- MB&F Official Technical Dossier: Horological Machine N°9 'Flow' (mbandf.com)
- Watches by SJX In-Depth Analysis: 'The Architecture of MB&F HM9 Flow'
- Monochrome Watches Technical Feature: 'MB&F HM9 Flow Dual Balance Planetary Differential'
- Maximilian Büsser, 'MB&F: 15 Years of Creative Horological Kinetic Sculptures'
Boutique Sales Enablement Dossier
Sales Enablement In Active Pilot
The luxury boutique sales enablement and client engagement dossier is currently piloted on flagship reference benchmarks: Day 01 (Rolex Submariner 126610LN), Day 02 (Omega Speedmaster 3861), and Day 08 (Audemars Piguet Royal Oak 15510ST).
Haute Horlogerie Technical & Advisory Suite: MB&F Horological Machine N°9 “Flow” (Course C20 Capstone)
Jev SystemOne 9.0+ StandardKinetic Horological Sculpture (Maximilian Büsser & Friends avant-garde horological art), Mid-Century Aerodynamic Streamlining (Inspired by 1940s-50s automotive speed records and aviation jet profiles), Twin Independent Balance Wheels (2.5 Hz / 18,000 vph oscillating in dual lateral pods), Central Planetary Differential (Mechanical averaging of dual rates: r_out = (r1 + r2) / 2 beneath signature battle-axe bridge), Vertical Heads-Up Driver Dial, Patented 3D Gasket Enclosure (Tri-part aerospace case in Grade 5 Titanium or 5N+ Red Gold, 5 sapphire crystals, 30m water resistance)
◆ Floor Quick-Reference Card: MB&F Horological Machine N°9 “Flow” (HM9)
The climactic finale of independent 21st-century horology, the MB&F HM9 Flow reimagines the mechanical wristwatch as a mid-century jet engine fuselage, housing two independent balance wheels linked by a planetary differential that drives a vertical instrument dial.
• Central Planetary Differential: Sits beneath MB&F’s iconic battle-axe bridge, mechanically averaging the rates of both oscillators into one output: r_out = (r1 + r2) / 2. Random positional errors cancel out mathematically by up to 29%.
• Patented 3D Gasket: Tri-segment case sealed with a complex three-dimensional elastomer gasket to provide 30 m (3 ATM) water resistance across 5 curved sapphire crystals.
• Driver’s Vertical Dial: Perpendicular dial allows pilot or driver to read hours and minutes at speed without rotating the wrist.
• Road Edition: Vintage automotive speedometer-style dial, red gold or rhodium movement finishing. Strictly limited production.
Advisory Tip: Have the client rest their wrist naturally on a steering wheel or table edge: demonstrate how the vertical dial presents the time directly in line of sight without any awkward arm contortion.
◆ Client Advisory Script: The “Is This A Real Watch Or Wearable Sculpture?” Dialogue
Context: A high-net-worth collector looking at the MB&F HM9 Flow asks why it looks like a jet fuselage, whether it is actually wearable daily, and whether dual balance wheels make it more accurate than a conventional chronometer.
Client Skepticism: “This looks more like a 1950s experimental fighter jet or a spaceship than a luxury watch. It’s 23 millimeters tall! How do I wear this, and why on earth does it need two balance wheels?”
Senior Horology Advisor Reframing: “Maximilian Büsser created MB&F around a single radical question: what if a mechanical watch wasn’t a flat circular disc designed to fit under a cuff, but a three-dimensional kinetic sculpture that tells time?”
Client Intrigue: “Explain the aerodynamic curves and the cockpit layout.”
The Dual-Balance Aviation Demonstration: “Notice the fuselage: it draws directly from post-war aerodynamic streamliners like the Mercedes W196 and the twin jet nacelles of a de Havilland Venom aircraft. When you slip it on your wrist, notice where the dial is: it is completely vertical. If your hand is on the steering wheel of your car or resting on your desk, you don’t twist your arm to check the time. You glance down, and the dial faces you directly like a cockpit instrument gauge. Now, look under the two lateral sapphire domes: those are two completely independent balance wheels beating at 2.5 Hertz. In between them, under that central battle-axe bridge, sits a planetary differential gear system. Each balance wheel has its own natural variances. The differential takes the mechanical rate of both oscillators and calculates their exact mathematical average in real time. If one balance runs slightly fast and the other slightly slow, the differential cancels out those positional variances. It is an extraordinary mechanical averaging computer.”
Client Realization: “And the engineering required to mill that titanium case?”
The Haute Horlogerie Capstone Close: “Milling that three-piece Grade 5 titanium case and sealing five separate curved sapphire crystals with a patented 3D elastomer gasket took MB&F three years of pure aerospace development. You don’t buy an MB&F HM9 Flow to tell people you have a nice wristwatch; you wear it because you are a patron of contemporary horological art. It is one of the most daring mechanical objects ever conceived in the history of watchmaking.”
◆ Clinical Diagnostic Dilemma: Planetary Differential Averaging Mathematics & Vertical Dial Winding Safety
Clinical Scenario: A client acquiring an HM9 Flow asks: “1. If one balance wheel is running at +8 seconds per day and the second is running at -2 seconds per day, how does the differential calculate the final rate? 2. How do I safely wind the manual movement and set the vertical dial without straining the 90-degree bevel gears?”
How does an accredited MB&F independent horology specialist explain differential averaging mathematics and proper crown operational protocol?
View Clinical Advisory Master Solution
• The planetary differential mechanically solves the arithmetic mean: Output Rate = (Rate A + Rate B) / 2.
• In the scenario (+8 s/d and -2 s/d): (8 + (-2)) / 2 = +3 seconds per day.
• By averaging two independent oscillators operating in distinct physical quadrants, independent random variances and position-induced fluctuations are mathematically attenuated by approximately 29% (standard error reduction: σ / √2).
2. Winding Protocol & Right-Angle Gear Protection:
• Winding is performed via the knurled crown situated on the rear fuselage between the two engine pods. Wind smoothly clockwise until distinct tactile resistance indicates the 45-hour single barrel is fully tensioned; never force past the natural stop.
• When setting the vertical dial, gently pull the crown out and rotate in a smooth, steady forward motion. Because the time indication is translated through a 90-degree conical gear train to reach the vertical face, rapid back-and-forth oscillating turns must be strictly avoided to prevent tooth wear on the micro-bevel pinions.