I have recently machined a threaded boss and two nuts in brass. I used Hex brass bar to produce the nuts, the boss would fit into the rear frame of the tuning capacitor with pressure on the rotor by adjusting the nuts on the threaded boss. The pressure is transferred to the rotor shaft by a small steel ball which sits in small counter bores in the rotor and the boss. The images tell the story. The thread size is 1/2" brass.
