"Bob Engelhardt" wrote in message
news
You are not ever going to find a ready-made wrench for that. The
welded-up suggestion is a good one. Another approach might be to
use a die grinder to cut the other 4 flats on your nut & turn it
into a hex. The nut being brass would make it more easily done.

However, fitting a wrench to that nut is likely to be only the first
problem in fixing that shower. After 60 years, that nut is not
going to come out gracefully and there's a good probability that
something will break in the process.

The right way to fix the valve is to replace it. I know, it's in a
tiled wall, but they make large plates to cover the hole.
Google/images "remodeling shower cover plate". Ask This Old House
did a segment on it:
https://www.thisoldhouse.com/how-to/...d-shower-valve

You might be able to fix the old valve, but you _know_ that it won't
be the end of it. Do it right, replace it, and be done with it.

I've partly disassembled a tree of old brass pipe from a contractor
neighbor's scrap pile. Some of the pipe-doped fittings unscrew fairly
easily, others require enough vise clamping pressure to crush the
pipe.

The pipe can be machined into 1/2" ID pivot pin bushings that
withstand more force than Oilite.

-jsw