The Sellita caliber SW220-1 is a Swiss made automatic watch movement with a day/date. This movement is based on the SW200-1 family framework, but is considered to be a clone of the ETA caliber 2836-2, with the same measurements and jewel count. Technical documentation for this calibre was found dated as far back as March 2012 and were revised in August 2017. You may see this movement spelled as SW220-1 or SW 220-1, Sellita has officially (and inconsistently) used both.
Some of the topics covered in this caliber listing:
Sellita SW220-1 VS SW200-1:
The main difference between the SW220-2 and SW200-1 is that the SW220-1 has a day of the week and date calendar complication, whereas the SW200-1 only has a date. Watches with either movement can have the calendar displayed at 3:00 or 6:00 on the dial.
Sellita SW220-1 VS ETA 2836-2:
ETA has a similar day/date caliber 2836-2 with the same measurements as the SW220-1. So, are these two movements are interchangeable? The answer is yes.
How accurate is the Sellita Cal. SW220-1?
The average accuracy rating of the Sellita SW 220-1 depends on the grade of the movement (Sellita Grades).
A note about grades: Although the chart above states that the anti-shock device depends on the grade (Standard/Special are sold with Novodiac and Premium/Chronometer are sold with Incbloc), this is not always the best way to identify the grade of your movement since brands can change the shock system themselves or special order them a certain way.
You will get better accuracy results with a full power reserve.
What is the power reserve on the SW220-1?
About 40 hours.
Although Sellita has been offering updated components to achieve an increased power reserve in some of their movements, the power reserve of the SW220-1 remains around 40 hours on a full wind. Sellita themselves present inconsistencies in their documentation. For example, in the official technical documentation (source) the running time is listed at 38 hours, however, the specs list on the SW220-1 page states: “Typical power reserve: 41 hours” (source).
How many turns of the crown to reach full power reserve?
Sellita does not really provide information about how much winding it takes for full power reserve on the SW220-1, only that it takes a minimum of 27 turns. Keep in mind that this movement is based on the SW200-1, so you may want to limit the manual winding of the movement (see here). This could explain why Sellita also provides and official recommendation pertaining to the max speed of 100 turns per minute. In other words, take it easy when winding your SW220-1 powered timepiece!
Which position should the crown be in?
Official Sellita documentation states that the crown should be in the time setting position before being extracted.
What tool should be used to extract the crown/stem?
Use a 1mm screw-driver to press the detent button. Avoid using tweezers or any other tool with a point because this could jam the setting lever and damage the setting lever spring.
During a service, Sellita states that any parts which are not new should be cleaned then treated with Moebius Fixodrop (ES/BS 8981) Epilame before assembly. As for lubricating the movement, they call for the lubricants listed below. Oil charts can be found on starting on page 11 of the tech docs.