A simple mechanical device

[mtbc]

I occasionally wonder about a simple but strange machine that was in my childhood home. I am probably quite wrong about the dimensions but the machine took the form of a hollow metal tube maybe a foot long, a couple of inches in diameter and plated with chromium or somesuch. It had a metal plate closing each end and stood horizontally on those plates, maybe an inch above the tabletop. Along the top of the tube but toward one end of it was a button atop a short lever: one could press the button down some; the lever would move a short distance perhaps around a hinge I barely recall. In the center of the bottom of the tube was a small, shallow, conical protrusion with a tiny hole in its tip: pushing the top button made a small metal spike protude maybe but a couple of millimeters downward out of that hole. There must have been a spring somewhere inside the tube: releasing the button returned the machine to its prior state. I have no idea what the use of this device was.

Comments

[aldabra]

I have a vague synapse trying to tell me this might be for tracing patterns by laying them over a piece of paper and making dents along lines, like pinpricks but less obtrusive, for dressmaking or leatherwork or something. But I can't dredge up any confirmatory facts or google images. And it seems odd to limit yourself to the middle of a foot, rather than having a handheld prong.

[mtbc]

I do like your tracing and denting theory even if we don't yet imagine enough to flesh it out! Thank you.

My father had a light-mechanical and electronic engineering background, if that's a clue, though I'm failing to construct something plausible involving figuring drill holes for component legs on PCBs.