Getting back to the question about the opener that cuts the can side
just below the rim, a key cranked geared opener that does this trick was
advertised in the 1928 Sears catalog (p. 690) as "The up to date can
opener / "Simplex" removes entire top from any shape can..."

Same design is in the 1936-37 Montgomery-Ward catalog #125 p. 411 as
"Star can opener / clamp it on edge of can and turn screw handle.  Cuts
cleanly below rim."

The last reference I have seen to these things is the 1940-41 Sears
catalog p. 887 as "Key-type pliers can opener.  Handy, compact,
efficient.  Firmly grips top-edge of can, cuts below rim, zips top
completely off.  Economical because cans may be re-used..."

If a company is claiming a new patent for these things, they have not
done a lot of research.  No wonder they went out of vogue- what a
vicious edge to leave on a can!

Have seen cans opened by these openers in mid-20th century arch. sites
in central Nevada

-Ron Reno