My buddy wants to build a string out of 452X and wants to know how many strands to use for a 60 to 70 pound bow? Also what is a good serving material for the center serving and the loops? He dosn't want a material that is too large and hard for the arrows to snap onto, so what diameter should he get? He also wants the serving material so it dosn't have a tendancy to slip on the string. Thanks for the help.