Even experienced professionals fall into these traps:
Elias knew that "winging it" with splines led to catastrophic vibration. He spent a rainy Tuesday navigating the British Standards Institution (BSI) shop ISO portal Bs Iso 4156 Pdf
If you are working on a legacy machine built before 2005, check if the original drawing cites BS 3550 (obsolete). In that case, you need a conversion table—available as a supplementary document from BSI. Even experienced professionals fall into these traps: Elias