Here's a fairly quick read re. copyright in the context of US law:
http://copyright.lib.utexas.edu/copypol2.html
I'm all for protecting private property, including intellectual property; w/out rights to our own properties, we have no other rights. However, there are solid arguments in favor of distribution of authored materials for educational purposes for the use intended by the materials' author and original intent. As I see it, academic institutions regularly utilize the Fair Use principle, as the purpose is to further distribute within the intellectual market the very materials needed to make any commercial application of such materials viable. In the simplest terms, an archaic machine itself loses its value -- commercial and practical -- when knowledge of its operation ceases to exist. (That is, separating the machine itself in the context of engineering and design and their necessary patents from an authored description of their operation, a necessary condition for the machine's original intent and purpose.)
It would be difficult to define an online group dedicated to vintage sewing machines, their use, operation and maintenance, history, etc. as anything other than an educational endeavor for personal enrichment.