I've been looking for days for a 5/16 x 24 coupling nut. I'm out in the boonies, so there's 2 little "local" hardware stores near me (less than 10 miles). No luck. The main stores (Lowes, Menards, Ace, Blains) are about 20 miles away. I called them all and nobody has the fine-thread (24), just the coarse (18). The Farm & Fleet guy said he had one, so I went there and it was the coarse-thread. Idiot!
A couple of the guys on the phone said they could order them, but they both would only sell them in quantity, and I'd end up spending about 20 bucks to get more than I could use.
Just gonna have to do things the hard way.
BTW, kidgambit.
Are you sure you didn't just screw a coarse nut onto a fine shaft?