The section titled key data for thread at the end of the pdf may be of use

http://www.georgefischer.co.uk/mallpipethreads.pdf

also

http://www.draughtsman.co.uk/informa...drills/bsp.htm

looks like 45mm tap drill from the last reference

wrote:

Hi
i need a data sheet for all BSP threads till 2". i can only find it
till 1" on the internet. particularly, i need the drill size for 1 1/2"
BSP.

thanks in advance.

aliT