3 sizes of radiator bleed valve screw...???

I've lost the bleed valve and during this freeze I'm not able to use the hall radiator which is making the house freezing - having gone to the big, small and interesting plumbers merchants I can only find one "new" screw which is smaller and has a tighter thread than the one I've misplaced (the rad has two screws so I've got one to compare to).

I read in a forum here (from ChrisR) that there are three sizes of screw - anyone what they are and how to find the other two???

thanks

Hi there,

Has this come out of the middle of the bleed valve.

The kind that is screwed into then end of the rad, or is that one that is "part" of the rad.

If the former, would be easier just to change the whole bleed valve.

Rico

the thread is in the rad itself...

I've also been down to the local tip (several times), the reclamation yards, and scrap metal yards... I probably would find one one day, but it's cold, and I want one just as soon as I can!!