According to my experience, the angular resilience of brass is 2-3 degrees, that of phosphor copper is 5-7 degrees, and that of stainless steel is 7- 10 degrees. The galvanized sheet does not need to rebound, and the angle of R is generally 90%, such as r 1.0, which is actually r0.9, but it is impossible to achieve the accuracy of 100% by any empirical formula. It is recommended to make fine adjustment after bending, which is foolproof.