Eterna Caliber 3501 Watch Movement

Brand	Eterna
Caliber Number	3501, EMC 3501
Movement Type	Mechanical, manual-wind
Shape	Rectangular
Lignes	10.75”’ x 13.25”’
Diameter	24mm x 30mm
Height	4.1mm
Jewel Count	18
Beat Rate / Frequency	28,800 bph / 4 Hz
Lift Angle	Unconfirmed
Power Reserve	~48 hours
Anti-Shock Device	Kif
Eterna Spherodrive?	No
Hand Count	3
Functions	Central hours; central minutes; central sweeping seconds
Hacking Seconds?	Yes
Country of Manufacture	Switzerland, Swiss made
Finishing	Damaskeening (stripes)
Known Models	Eterna Madison Three Hands (Add your watch to the comments below…)

Eterna caliber 3501 is a rectangular handwound mechanical watch movement. This movement is a 3-hander without a calendar.

You may also see this movement listed as “EMC 3501”. EMC stands for Eterna Movement Company (not Eterna Manufacture Caliber).

Eterna 3501 VS 3505:

There is a similar rectangular caliber 3505 with the main difference being that the 3505 is equipped with Eterna’s Spherodrive system – allowing for a longer power reserve as a result of less friction and lost energy. This is how Eterna described the two in marketing materials from around 2013:

“In a conventional watch movement and in the Eterna 3501 calibre, one end of the barrel arbour supporting the barrel and the mainspring pivots on the base plate, and the other in a bridge. In the Eterna 3505 movement with Eterna Spherodrive, the smooth bearing for the arbour in the barrel and the two smooth bearings for the arbour in the base plate and in the bridge are replaced by an innovative lubrication-free double ball bearing mechanism.”

Other differences are that the 3501 has 18 jewels and 2 ball bearings, while the 3505 has 17 jewels and 6 ball bearings.

Interesting note: Eterna marketing materials from circa 2012 mention that the 3501 has 19 jewels and the 3505 has 16 jewels. Real world images show that the 3501 has 18 jewels and the 3505 has 17 jewels. The reason for the discrepancy or change in jewel count remains unknown.

Can the 3501 be overwound?

According to the official user manual, the 3501 cannot be overwound – unlike most handwound watches.

“A lock mechanism ensures that the movement spring cannot be over-wound.” -3501 User Manual (page 4)

Recommended Service Intervals:

With regards to the recommended service intervals for 3501 powered watches, Eterna states:

“It is advisable to have your watch overhauled and fully cleaned at least once every 4 years, and in particular to have the movement overhauled, since its operation may be disrupted due to the ageing of the oils and grease.” -3501 user manual (page 8)

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