On Sun, 5 Feb 2006 16:57:40 +0000 (UTC), Frank Erskine
wrote:

I'm trying to find out whether the ¼" bush for a camera tripod is a
Whitworth or a UNC thread - both are 20 tpi, but of course the thread
form is different.
Any ideas please?

I'm pretty sure it's UNC.

From memory a gutter bolt fits.

sponix