Many builders use/used investment cast or machined steel plugs inserted into or over the tops of the seat stays.
http://www.framebuilding.com/
The flat sheet metal seat stay caps are a lot more work and the over sized ones can be more so to keep them properly located while brazing. It's very easy to overheat the thin sheet metal.
The flat brazed on caps and fluted brazed caps can be filed to size to be flush with the outside diameter of the seat tube but they are still a lot of work.
Chas. Colerich Oakland, CA USA
marcus.e.helman@gm.com wrote:
> I have always thought the oversized caps looked sloppy, like the builder
> could not be bothered to do the work necessary to get the caps flush with
> the stays. Is this just another esthetic approach to ending the seat
> stays? Is there more to it than that?
>
> Best regards,
> Marcus Helman
> Detroit, MI