I guess we should break the 1890-WWII into two groups: 1890-WWI(actually maybe a few years prior to WWI, say 1910) & WWI-WWII. The period of WWI-WWII would have been greatly affected by military production. This allowed them to heavily invest in machinery. But from the mid 1800s to say 1890, they craftmen were divided into distinct tasks.
Zacharias Anschultz,
Caspar Schilling,
Egydius Schilling,
Heinrich Schilling,
Gottfried Klett,
Valtin August Klett,
Gustav August Gruber
& the Jaeger boys, who were also master borers,
all either owned a pipe/tube forge or operated one. From what little I know about the pipe/tube hammer/forge, it wouldn't be under the same roof as the rest of the facility as at the end of a day all would depart deaf and cross-eyed. I'll check with Mike Ford and get his opinion. But many of the Sauer tubes have a Schilling forge stamp as well as a Fraktur/Gothic J which I think to be for the Jaeger. When a "K" is encountered it is usually for one of the Klett boys. So were they subs or were they employed by Sauer? For now I can't say.
Kind Regards,
Raimey
rse
