Paul K. Dickman wrote:

Ya, that's probably off an atlas six.
They are a zamak gear with a 1/2" bore with two keyways, and stack on a
babbitt bushing with a 3/8" bore.

And they self-disintegrate over the years too. My father-in-law had 2 Atlas
6" lathes. The first one he junked (by tossing it down behind his workbench)
because of the "rotting back gears" problem.

Grant