Another key and more questions.

Doug MacQueen

I recently purchased this wonderful key mostly to research the method of manufacture. Certainly blacksmith made and several hundred years old.
There is no evidence of it being soldered together. However it occurred to me that forge welding may be involved. Any thoughts?

Richard Phillips

Diderot’s Encyclopedia shows something of how keys were made. The original french text as printed, is difficult to read in facsimile which has been archived
https://archive.org/details/encyclopdieoudi03alemgoog/mode/2up?view=theater
and it still uses the long ‘s’.
There is some English translation, but i have not found anything on locks and keys. There are Internet copies of the relevant plates
https://quod.lib.umich.edu/d/did?didno=did2222.0001.607;rgn=full+text;size=50;sort=occur;start=1;subview=detail;type=simple;view=reslist;q1=lock

https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Ftse1.mm.bing.net%2Fth%2Fid%2FOIP.l8R7iSTjaAKth_lj_k8jNgHaL_%3Fpid%3DApi&f=1&ipt=8a6080ea98d285462ddc09fb986f7d5d9834e71fc80daced3ffc03c63fd5ee3d&ipo=images
Unfortunately the resolution is poor and they do not enlarge well.
Some of the design was forged, using various dies/swages. Must have been hard work by hand then. My practical experience of blacksmithing is very limited, others here know much more.