Hi there....Jonsvba ......Thanks for that , ..Actually I didn't learn it anywhere...I just sort of picked it up as I went along...over the last 40 years or so......If you'd like to look in on " My BE2b reproduction " thread.....(about 15 items ago on the "full" version of Replica Aircraft thread list ) , in answer to Maxim 08 (John), I gave a brief history of my work in engineering......I understand that you're about to join the " mad brigade "....Cheers...John