Mbf Caliber Legacy Machine Perpetual

MB&F Caliber LM Perpetual

Mbf Caliber Legacy Machine Perpetual

Caliber NumberLM-Perpetual
TypeManual wind
Number of Parts581
Power Reserve72 hours
Vibrations Per Hour18,000 bph (2.5Hz)
FunctionsHours and minutes at 12:00, day of the week at 3:00, date at 9:00, month at 6:00, retrograde leap year between 7:00 and 8:00, power reserve indicator between 4:00 and 5:00
Manual winding with double mainspring barrels. Bespoke 14mm balance wheel with traditional regulating screws visible on top of the movement. Superlative hand finish-ing throughout respecting 19th century style; internal bevel angles highlighting hand craft; polished bevels; Geneva waves ; hand-made engravings.
Country of ManufactureSwitzerland
Known Models
Legacy Machine Perpetual

The MB&F LM Perpetual is an in-house perpetual calendar movement that was originally launched in 2015 in the Legacy Machine Perpetual. This caliber is hand-wound with double barrel springs, allowing for up to 72 hours of power reserve.

Fool Proof Perpetual Calendar:

In the words of Maximilian Büsser:

“I call perpetual calendars boomerang watches because they come back for repair so often. The mechanisms jam, block, break, or jump days when they shouldn’t.”

Anyone who has ever owned a mechanical perpetual calendar timepiece knows how sensitive they can be to making adjustments. Most watches like this include instruction manuals warning not to change certain calendar displays at certain time because it can seriously damage the movement. The MB&F Legacy Machine Perpetual wanted no part of that tradition:

“The aim here was to create a calendar which is fool proof. You can press the correctors whenever you like. You can manipulate it any way you like. Whatever you do, you’re not going to break anything, you’re not going to damage anything.” -Stephen McDonnell

This works thanks to a safety feature that automatically disconnects the quickset pushers while the date is being changed over. Therefore, it is not possible to cause damage during the changeover. No pusher tools are needed for adjustment.

Mechanical Processor:

MB&F is calling this innovative technology a “mechanical processor” and it is currently patent pending.

“This revolutionary processor takes the default number of days in the month at 28 – because, logically, all months have at least 28 days – and then adds the extra days as required by each individual month. This ensures that each month has exactly the right number of days. There is no “skipping over” redundant days, so there is no possibility of the date jumping incorrectly.”

Mbandf Mechanical Processor

It also accounts for leap years without needing to be adjusted.

“Using a planetary cam, the mechanical processor also enables quicksetting of the year so that it displays correctly in the four-year leap year cycle, whereas traditional perpetual calendar mechanisms require the user to scroll through up to 47 months to arrive at the right month and year.”

Perhaps the irony of the LM Perpetual is that it’s a fool-proof perpetual calendar mechanism which doesn’t need touched.

World’s Longest Balance Wheel Pinion:

The Legacy Machine Perpetual displays a suspended 14mm balance wheel on the top of the watch, as part of the dial, and places the escapement on the bottom. The achieve this, they needed to invent an extra long balance pinion to connect the balance to the escapement.

Caliber Number:

As seen with the innovative designs in their timepieces, it’s clear that MB&F doesn’t color within the lines, they are independent in every sense of the word. This even carries over into the way they designate their calibers. Unlike most brands that use a numbering system, MB&F calls this caliber by the same name of the watch itself.

This movement is in the Legacy Machine Perpetual watches, therefore it is considered to be MB&F caliber LM Perpetual.

Partnership Project:

The LM Perpetual is a project with Northern Irish watchmaker Stephen McDonnell.

“McDonnell had been a long-time Friend of the brand and played an instrumental role in the realisation of MB&F’s very first timepiece, Horological Machine No.1. As Büsser was thinking of developing a perpetual calendar for the fourth watch in the Legacy Machine collection, McDonnell replied that he had an idea for a perpetual calendar that addresses many of the drawbacks associated with conventional examples.Three years and a great many sleepless nights later, Legacy Machine Perpetual was born.”

Limited Edition:

The LM Perpetual is available in the following configurations:

  • Grade 5 titanium with green face (limited to 50 pieces)
  • Platinum 950 with blue face (limited to 25 pieces)
  • 18k red gold with grey face (limited to 25 pieces)
  • 18k white gold with purple face (limited to 25 pieces)
  • 18k white gold with dark grey face
  • 18k yellow gold with blue face (limited to 25 pieces)

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Examples of watches with this movement:

Additional Resources:

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