Dating waltham movements
The pictures on this page can help to identify movements without seeing the keyless work, but be careful to make sure that all the features, the shapes of the plates and bridges, the placement of the screws and pivots, are exactly the same; similar is not close enough!
If you click on the pictures a bigger one should pop up in a new window.
Movements from the 1920s or earlier, with cover plates that don't have integrated detent springs, don't generally appear in the Bestfit or similar books and are therefore harder to identify. There are hundreds, possibly thousands, of different Swiss movements.
The setting lever spring was an evolution of the earlier simple cover plate that simply kept all of the parts of the keyless work in place.
Stem set keyless work needs a detent to hold the crown in the winding or setting position.
I don't mind you using these for your own personal research, but if you want to use them elsewhere such as on an internet forum, a web site, or in a publication, please read my copyright notice first and include attribution.
If you have any questions or comments, please don't hesitate to contact me via my Contact Me page.