[Shop-talk] What the heck screw do I need? And where do I get one?

[David Scheidt]

I have a number of door knobs that need set screws to hold them to
their spindles.  (Square threaded spindles in mortise locksets.)  The
normal size of these is 1/4-20 or rarely 5/16-24 or even more rarely
1/4-28.  The existing screws are 28 tpi, with a major diameter of
0.280.  That's no screw thread I know of, but I have a house full of
them (identical glass door knobs, presumably original to the house,
circa 1925.) so it must be something.


-- 
David Scheidt
dmscheidt at gmail.com