Bicycle Mechanics - Raleigh rear der anti-pivot nut threading

I lost the screw that hold the antipivot nut of an 30+ year old Raleigh Grand Prix rear derailuer (Raleigh brand on the der)-I still have the nut-i.e. the nut that goes into the dropout of an axle mount rear der to keep it from pivotting. Anyone know anything about the threading on the nut I'll need to replace it-can I use hardware theading, will it be special bike threading, metric threading, etc? If special bike threading, is it still available or will I have to pull it off another axle mount der of that era?

Slightly puzzled by the term 'antipivot' nut but the der hanger screw standard
is 10Mx1.0 thread. This is standard (fine thread metric) size, also the same as
the axle threading in the rear. Campy used to use 26TPI to be obstinate, but
the differences are miniscule, or are you referring to something else?

He's talking about the old style claw hangers that were held on by the wheel nuts and had a small bolt and special nut to stop them pivoting around the axle.
Seeing you have the nut, take it to your local hardware store and try them until you find one that fits. It is more than likely to be metric. Be careful you don't go too long as the bolt will interfer with the chain/freewheel.

I've had to find a couple odd sized fasteners lately and found the big box and even mom and pop hardware stores don't have the size. I resorted to a no kidding nut and bolt supply outfit to find the correct size.

Slightly puzzled by the term 'antipivot' nut but the der hanger screw standard
is 10Mx1.0 thread. This is standard (fine thread metric) size, also the same as
the axle threading in the rear.

Only because I care :), M10 x 1.0 is metric extra fine, M10 x 1.25 is metric fine and M10 x 1.5 is metric coarse. Both of the fine pitch varieties are next to impossible to find at any normal hardware store. The extra fine pitch might as well be an endangered species as you will rarely if ever see it (outside of bicycle wheel axles of course).

try a ace hardware store , they seem to have a wide section of metric hardware, if that fail try your lbs , they should be of help.

Maybe find a trashed old bike and take it from there. I've got a couple out in the garage you could have. Doubt it would be worth the postage.

Even in Metric threading pre ISO there were thread pitch variations that were country specific. Early Japanese motorcycles, and possibly bikes, used JIS metric fasteners. Difficult to find today if needed. France had it's own pitches for metric threading for pre ISO standard metric threads too as did Germany from what I have read. Just because it is "Metric" does not mean much on older equipment.

Also lots of proprietary threads in the bike industry such as Raleigh, Chater Lea, Campy etc and older brit bikes have Whitworth and BCI fastener threads to contend with too.

Can make bike restoration or finding current fasteners which fit older threaded parts challenging to say the least. A thread pitch gauge set, metric and english, is your friend!