Here are the first few keys for my glockenspiel. I crept up on the finished lengths of the first two bars, taking 0.1mm increments and measuring frequency. With the remaining six I put my trust the physics and was surprised by how well tuned they turned out.
For those interested in the physics, the ratio of frequencies differing by a semitone is 2^(1/12).
Also the fundamental frequency of a bar is inversely proportional to the square of its length.
Thus the ratio of bar length between semitones is (2^(1/12))^(1/2) = 2^(1/24).
For example if it is known that say a bar tuned to C is 200mm long then a bar tuned to C# is given by:
Length(C#) = Length(C) / 2^(1/24)
Length(C#) = 200 / 2^(1/24) = 194.31
