[dsfyu404ed]

The spec is almost certainly for the machining after it's been forged.

[WalterBright]

I would have loved to take a field trip to Saginaw Gear and see all the various steps in its manufacture.

[dsfyu404ed]

Like this but bigger.

https://www.youtube.com/watch?v=dzIsR4Mg158

"ball screw" and "lead screw" are your search terms. For aerospace it's gonna also be center drilled to save weight as well.