I’ve been asked to make three interlocking bangles like a huge Russian wedding ring. I will be using 3.2x1.9mm oval sterling silver wire. The bangle sizer I have is numbered and she wants a No18, this equates to a 65.07mm diameter though it measures 65.4 with a calliper.
My question is what formula do I use to get the right size, as an engineer teaching metal bending we used the formula pi x d+1/2t, with rings I normally use pi x d+t where d is diameter and t is thickness, pi being 3.142, I have assumed that for three interlocking bangles they should be pi multiplied by the diameter plus three thickness’ is this right, I don’t want to mess it up.
Any advice would be much appreciated, I’ve bought enough metal to have two attempts just in case.