I found a set of four of these on an 1890-1910 panel saw. Otherwise unmarked/unbranded;but with these sawscrews, where the steel central studding was peened into the face-side [unslotted] nut, but turned into the reverse-side [slotted] one. Give the problems with full brass sawscrew shanks being eroded away by fretting against the plate - if there's any movement - this seems like a better solution. And although the saw itself is nothing special, the fit of the nuts on each side into the tote was significantly tighter and more precise than any I've seen elsewhere. Has anyone got information on them?