Hello,

Just a great deal of trial and error. The Wikipedia article on screw threads helped me a great deal to realize that instead of having to use a calculator for anything all that was needed was the base pitch number and everything else is ratios. I also thought it would be good to have MoI do the precise calculations for me rather than rely on pen and paper. FelixPQ was kind enough to send me some engineering handbook scans as well for reference.

Well here is my result, I got bored and decided to play with my nuts :¬)

Also this link may be of use to someone else with what was our conundrum ... http://www.roymech.co.uk/Useful_Tables/Screws/Hex_Screws.htm

Martin