Identify Screw Threads from Major Diameter and Thread Pitch
If you spot an error let me know or if you think I have missed a series out out.
Or any comment.
The table, on the attached link, lists most major thread series sorted in order of increasing Major Diameter then Thread Pitch, from 3mm to 3/4"
Measure the thread Major (outer) Diameter and then the Thread Pitch, and try looking it up.
This is not guaranteed to get you the answer but might help.
info is included for for:-
Metric (Coarse and Fine)
Old French Metric - only where not the same as Metric Fine or Coarse
System Français (SF) - only where not the same as Metric Fine or Coarse
Unified Coarse UNC - which covers American National Coarse ANC
Unified Fine UNF - which covers American National Fine ANF
Unified Extra Fine UNEF
British Standard Fine BSF
British Standard Cycle BSCy
British Standard Pipe Parallel BSPP
British Association BA
(Grey Cells are calculations from imperial to metric or the other way round)