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It is my impression that ETA's calibre 2892-A2 is usually found in more expensive watches and in luxury watches where oftentimes the movement has been modified. Mechanically, I don't think the 2892-A2 is superior to ETA’s classic 2824-2. Both movements have the same diameter (11 ½´´´ Ø 25.60 mm), the same frequency (28’800 A/h), and the same date complication. The decisive difference is the thickness where the 2892-A2 is one-millimetre thinner (3.6mm). That, combined with being a reliable and well-functioning movement, has made it popular for additional complications and alterations such as moon phase, power reserve display, co-axial escapement, chronograph modules from Dubois Depraz, and so on. The Swiss Sellita Calibre SW300-1 is, as far as I understand, an excellent clone of the 2892-A2. There is also a Chinese clone, the Seagull Calibre ST1812 (reviewed by @Markin the video “Chinese eta 2892-A2 Clone - Service and Review - Seagull ST1812”), and possibly others. Mark has made a playlist of videos that excellently demonstrate how to service the ETA 2892-A2 movement. The playlist is named: "Omega 2500 Co-Axial Stripdown and Service (ETA 2892-A2)" I recommend Mark’s playlist for several reasons. Among other things, he shows how to mount the barrel bridge safely and how to hold the minute train bridge with your tweezers to easily get it into place on the main plate (which I found a bit fiddly). In addition, he shows and compares the parts that are all too easy to mix up. One thing that is not shown in Mark's service video is that the Incabloc setting (chaton and cap jewel) for the balance and the main plate have different diameters. The main plate Incabloc setting diameter is smaller than that of the balance. The reason this is not shown in the video is probably that Mark removes, cleans, and lubricates the Incabloc settings one at a time after he reassembles the balance, so he wouldn’t notice. Anyway, don't mix up the two sets! Something that I appreciate about Mark's videos in general and that sets him apart from basically all other watch repairers on YouTube is that he doesn't continuously babble in his videos but mainly talks to make clarifications. I enjoy those segments of silence where I can just focus on the work being done. When I started my service, I decided to follow Mark's disassembly which worked perfectly. But for the assembly, I made up my mind to follow ETA's technical documentation to the letter. It turned out to be a mistake. In ETA's documentation, the assembly of the movement begins with the keyless works, then the train of wheels and then the barrel bridge. The crucial problem with this arrangement is that it is physically impossible to mount the barrel bridge if the train of wheels is already mounted. It is also very fiddly and difficult to baste the end of the winding stem into the winding pinion hole because the hole for the winding stem in the main plate is both open and tapered and therefore does not hold the winding stem. Mark takes a considerably more hands-on approach. He begins the assembly with the barrel bridge. He then mounts the keyless works whose constituent parts (the winding stem, the winding pinion, and the sliding pinion) are supported by the underside of the barrel bridge, making it considerably easier to get the keyless works in place. After I revised my strategy, this service walkthrough now follows Mark’s approach. It surprises me, but it seems like no watchmaker has proofread ETA's technical documentation. Alternatively, ETA follows an established practice and expects those using the documentation to understand that the assembly order in the document is not significant. I am also somewhat sceptical of ETA's recommendations regarding lubrication. Where we traditionally use grease, for example in the keyless works, ETA chooses mainly oil (HP-1300). I guess that ETA treats all parts of the movement with epilame (Fixodrop) and that oil may then be a better alternative. For better or for worse, my service walkthrough follows ETA's lubrication recommendations. As usual, I would like to remind those of you with no previous experience in watch servicing that this service walkthrough should not be seen as a tutorial on how to service a watch movement. A lot of tools, consumables, training and know-how are required to succeed. Fortunately, there are several excellent resources and watchmaking schools online. When looking through the pictures you’ll see that a few screws and plates are either marred or have pits and grooves in them. None of this is my doing but is either the result of rust (that I removed) or the doings of a less scrupulous repairer than myself. Finally, someone may ask, “Why to bother to do a service walkthrough with pictures when there is such an excellent video?" The main answer to the question is that I find it interesting and fun, and I see it as a complement to Mark's service video. Using this walkthrough, you can quickly scroll through the pictures to read what the different parts are called and where and in what order they should go, what the screws to be used look like, and to read ETA's lubrication recommendations. So, I hope you’ll find this ETA 2892-A2 service walkthrough useful, now or in the future. *** ETA Calibre 2892-A2 Disassembly *** ' *** ETA Calibre 2892-A2 Assembly ***
Just uploaded a new four part series on the Omega Seamaster Co-Axial (with a 2500 movement). This is about 1 hour long so I have split it into four parts. https://www.youtube.com/playlist?list=PLwP8fNxqhOvPfgwFF1qHaERl5DuZ-zXqA