03-09-2020, 07:38 AM
(02-09-2020, 08:48 PM)Parazine Wrote: Likely these are watchmakers sizes, which seem to be a closely guarded industrial secret. I suspect they're a metric based system of some sort.....
Certainly the the later magnetic Speedos etc. used an odd metric fine thread. Someone who had worked at Smiths told me that this came about as a result of Smiths taking over Jaeger instruments and using their designs. There's a huge amount of general thread information on this website: https://www.gewinde-normen.de/en/index.html e.g. Bodmer thread or Whitworth instrument thread etc.