It needs to be in the C4 major scale, and the diameter of the copper pipe is 1/2 inch, the smallest kind at Home Depot. I calculated it incorrectly and my glockenspiel sounds terrible!C5 is 0.366 m in length.
the easiest way is to use a chromatic tuner. start with your pipe on the long side and shave off a little at a time until you hit the correct pitch.
There are different types of pipe, with different wall thicknesses and temper. Perhaps the calculations were to a different type of pipe.
