====== Omega 3861 ======
**Calibre 3861** is a [[manual winding]] [[chronograph]] movement from [[Omega]] produced since [[2019]].

===== History =====
[[Lemania]] created [[Lemania 1872|a family]] of [[cam switching]] [[chronograph]] movements in the 1960s just as chronograph watches were becoming more popular in the mass market. The [[Lemania 1873|Lemania Calibre 1873]] was part of a family of similar 12 [[ligne]] movements, running at 21,600 A/h and lacking modern features like [[hacking seconds]] or [[automatic winding]]. In [[1968]], [[Omega]] selected the Lemania 1873 as the basis for their [[Omega 861|Cal. 861]], used in the [[Omega Speedmaster Professional]] line of watches. Omega updated the finishing and materials of this movement in [[1992]] and [[1996]] (becoming the [[Omega 1861]]) but the basic movement remained the same for 50 years.

In March [[2019]], Omega introduced the [[Omega Speedmaster Professional 310|Speedmaster Apollo 11 Anniversary Limited Edition]] to celebrate the 50th anniversary of the Apollo 11 moon landing. This watch featured a new movement, this **Cal. 3861**, which improves on and modernizes the venerable Cal. 861. Chiefly, the movement adopts Omega's signature [[co-axial escapement]], a major accomplishment of engineering. Omega also added a [[hacking seconds]] lever, a surprising omission on 50 years of [[Omega Speedmaster Professional|Speedmaster Professional]] watches. Many components are made from durable material, chiefly the [[free-sprung]] [[balance]] uses a [[balance spring]] constructed of [[silicon]]. This gives it [[magnetic resistance]] to 15,000 Gauss and, combined with factory adjustment, earns it a [[METAS]] [[Certified Master Chronometer]] status.

Like all previous movements in this family, it features a 30 minute chronograph counter at 3 00, a 12 hour counter at 6 00, and [[small seconds]] at 9 00. It is plated in gold or [[rhodium]] and finished with [[Geneva waves]].

===== Movement Family =====
  * [[Omega 860|Cal. 860]] (1968-) - 17 jewels, no 12 hour counter
    * [[Omega 861|Cal. 861]] (1968-1992) - 17 jewels
    * Cal. 862 (1968-) - 21 jewels
    * Cal. 863 (1980-1987) - [[Rose gold]] plated and decorated, 21 jewels
    * Cal. 865 (1967-1968) - 17 jewels, [[monopusher]], no counters
    * Cal. 866 (1968-1992) - [[Moon phase indicator]] at 12 00 and [[date]]
    * Cal. 910 (1969-1971) - Adds 24-hour [[second timezone]] set by pusher
      * Cal. 911 (1971-1972) - [[Small seconds]]
    * Cal. 920 (1968-1970) - [[Monopusher]] with no counters, date
    * Cal. 930 (1969-1970) - [[Bullhead]] version
  * Cal. 861 (1992-1996) - 18 jewels
    * Cal. 863 (1993-1996) - [[Yellow gold]] plated and decorated, 21 jewels
    * Cal. 864 (1992) - [[Chronometer]] rated
    * Cal. 866 (1985-1988) - [[Moon phase indicator]] at 12 00 and [[date]]
    * Cal. 867 (1992-1994) - [[Skeletonized]] by [[Armin Strom]], 21 jewels
  * [[Omega 1861|Cal. 1861]] (1996-) - [[Rhodium]] plating, 18 jewels
    * Cal. 1863 (1994-) - [[Gold plated]] and decorated
    * Cal. 1866 (1999-) - [[Moon phase indicator]] at 12 00 and [[date]]
      * Cal. 3604 A (2003) - [[Skeletonized]] Cal. 1866
  * Cal. 3861 (2019-present) - [[Co-axial]] escapement, [[silicon]] balance spring, [[anti-magnetic]], [[chronometer]] rated


<WRAP ud ud_mov>

**Description:**
  * [[Manual winding]] movement, [[co-axial]] [[chronograph]]

**Functions:**
  * Hours, Minutes
  * [[Small seconds]] at 9 00
  * [[Chronograph]] 30 minutes counter at 3 00, 12 hour counter at 6 00

**Data:**
  * 12 [[ligne]]
  * D 27 mm, H 6.87 mm
  * 26 [[jewels]]
  * 21,600 A/h
  * Power reserve 50 Hours

**Production period:**
  * [[2019]]-Present
  * Predecessor [[Omega 1861]]
</WRAP>

{{tag>Movements Lemania_calibres Manual_winding_movements Chronograph_movements Omega_chronograph_calibres}}