TIL about BSW screw thread standard https://en.wikipedia.org/wiki/British_Standard_Whitworth

Came across this when a local store gave 1/8" screws and a thread tap instead of M3. Seems to be still used in some of the equipments in India? The screws and thread tap was a bit rusty though, might be old as well.

This answered why some of the bolts I already have are different than metric ones. 😄