Some of the topics covered in this caliber listing:
Sellita officially spells this caliber as: SW510 BH a.
This is one of the caliber numbers that has been caught in Sellita’s growth and extensive movement offerings – like an overwhelming 20 page menu at a restaurant. Spaces are not a good idea in a caliber number, it’s bad for SEO and potentially causes caliber confusion in the community when letters are left off.
Because of this, it appears that some brands have come up with their own way to write out the caliber number (although neither is in line with the actual manufacturer’s spelling, you can’t blame them. Also, it’s already admirable that they went as far as putting the actual caliber since there are still many brands that do not).
Christopher Ward writes it as SW510 BHa.
Titoni writes the number as SW510BHa.
Vandaag spells it as SW510BHa.
There are other Sellita calibers similar to the SW510 BH a, including the SW510 BH b, SW510 M BH a, and SW511 BH a.The main differences are as follows:
SW510 BH b – No date version of the SW510 BH a.
SW510 M BH a – This is the manual-wind version of the SW510 BH a.
SW511 BH a – same as the SW510 BH a with the exception of the 15 minutes chronograph counter at 3:00 rather than the 30 minutes counter found on the SW510 BH a.
Grades of SW510 BH a:
There are three grades available for this caliber: Elabore, Top, and Chronometer. Learn more about Sellita grades here.
Removing the Crown and Stem:
According to official documentation, Sellita states that the crown should be pulled out two clicks to the hand setting position before attempting to remove it. Find the detent button slot on the movement near the crown area and use a 1mm screwdriver to press while pull out the crown/stem. Do not push too hard!
As of this caliber listing, there does not seem to be a supplier with individual SW510 BH a movements available for sale. If you need a part for service or repair, it’s possible that most parts from the base SW510 would be suitable, however, you should study the tech sheets to be sure.
There is not a specific technical document for the bi-compax date version of the SW510. Sellita points the variants to the main SW510 docs. This is unfortunate if you’re specifically working on an SW510 BH a movement, but it’s likely that Sellita would be able to provide the corresponding documentation to an individual or organization which has placed an order for raw movements of this caliber number.
If you have wholesale information (pricing, minimum order quantities, lead-time) that you’re willing to share, please add it in the comments below.
Watches with this movement:
The caliber image above was found in a Titoni Heritage Bi-Compax Chronograph watch. The brand has several models using the same movement. Christopher Ward is another watch brand using the SW510 BH a in the C65 Chronograph model. Additionally, a microbrand called Vandaag also uses this caliber in their Schallmauer model.
Bonus: Mathey Tissot also lists this caliber as being used to power their Type XXIISE (Homage Type XX Chronograph) watch, but based on the stock photo here, the watch is a no-date. This means either they don’t realize they are actually using an SW510 BH b, or they are using an SW510 BH a and it has a phantom date position. Frankly, either reason is frowned upon, and it’s not being listed here without verification.