by Eric the Viking » 19 Sep 2021, 12:30
I also use them for marking. I have a box of the "fat" ones bought some time late in the last millennium (no idea for what!), and that's pretty much all they ever get used for.
Assuming you have either a set of diamond needle files or a set of diamond-grit "burrs" for a Dremel, processing them is fairly easy: chuck the pin in the pillar drill, select a slow speed and remove the bulbous head (I prefer to do this with the edge of a diamond file).
You can now chuck it t'other way round easily, so swap ends, and file or grind to be pointier than before, using weapon of choice (for me that's a diamond burr). It's a faff to keep taking it out of the chuck to cool it, so I just go slowly.
As I'm lazy, I usually just put a point on it and be done, but you can make small edges for cutting gauges etc., I guess. They are cut/polished by wet+dry paper - I use diamond tools for convenience, but you can enhance the edge on a stone or using Scary Sharp techniques.
The last time I did this was to make a large, wooden set of compasses, for which it was a perfect solution.
So they do have some use. But I have no idea what metal they are (but mine are BZP), although I do know where the box is, so I'll have a look in case...
... [later] The box just says they are hardened and zinc plated. Sorry.