Well, #MachinerysHandbook has let me down for the first time in about two decades. All I wanted to know was the nominal diameter of a brass rod if I want to #die-thread it for #6-32 using a standard #SAE die.

It 𝘢𝘱𝘱𝘦𝘢𝘳𝘴 I can use ⌀ 0.125" if I'm careful, move slowly, clear the die frequently, and use a lot of #TapMagic. I have several inches to thread, so I'm extra glad I have my #lathe and #tailstock for rigidity and control. (Never threaded on the lathe. Yet.)