It’s o-rings and spacers stacked and compressed, pushing the o-ring out like an expansion collet.
And here it is with a part on it.
Ohhh I thought for metal. For plastic this makes sense. I’d think for metal it’d come loose.
pretty boring
So it’s a lathe?
The whole thing is a lathe, yes, but what they are pointing out is the fixturing on the lathe. Specifically the piece in the chuck that can clamp onto the ID of a work piece to be cut. Which is pretty neat!
Ah a Joe Pie classic. If you’ve seen his videos, you know.