The "cake slice lifter" is a clock makers screw plate for indenting (early cold forming!) threads on brass clock plate spacers (no cutting).
Graeme
That's my thought, too. I found the following on the Davistown Museum site:
"Screw plates of hardened steel were used to form the threads of screws for clock and watch work. Each plate had threaded holes, in twos or threes, of diminishing sizes for different-sized screws. The action in making the thread was to squeeze the thread on the softer metal of which the screw was to be made. The tool was used by holding the wire to be screwed in a vise and turning the tool onto it by hand. Small screws could, however, be turned into the plate. The handle on each plate provided leverage and in some had a convenient loop for hanging the plate on a hook when not in use (for larger sizes, see PI. 34). A lubricant such as lard oil was essential in screw making. "
