Wind Chime
In the winter of 2004, I built a windchime with 5 chimes. It uses the pentatonic scale, in which an octave is divided logarithmically into 5 parts.
The chimes are made from pieces of 0.75 inch diameter thin walled copper plumbing pipe. The longest chime is 5 feet long and this length sets the base length of all the rest, it is the lowest frequency chime. The chimes are attached using 20# fishing line to a point 1/3rd the way down each chime. This point is drilled with a small drill that is slightly larger than 12 gauge house wiring. Scraps of 12 gauge solid copper wire are used as attachment points for the fishing line.
The fishing line is tied from each chime up to a 2 inch thick and 10 inch in diameter cross-section of a limb cut from an Ash tree. The center is drilled out in this cross-section with a 15/16 inch drill. The perimeter is drilled for attachment points for the fishing line and 3 attachment point for the cord that will support the entire assembly. Down through the hole from the attachment point for the entire assembly a cord runs to the gong. The gong itself is made from a short piece of Apple tree limb about 12 inches long.
The circular disk of ash used on top was sanded on each flat surface treated with spar polyurethane, 4 coats. The gong apple piece was de-barked and sanded, with the sharp corners rounded on the bottom. Then boiled linseed oil was applied, 2 coats. The copper pipes were also given 2 coats of boiled linseed oil.
Boiled linseed oil is easy to work with and does not have obnoxious fumes. It penetrates wood well. On metal it forms a waterproof layer and provides a degree of oxidation protection. Linseed oil, derived from flax seeds, has good antioxidant properties. The oils in flax seed are actually a good dietary supplement, containing Omega-3 fatty acids, the same good fats found in sea food. Another fact is that Linoleum, is made from linseed oil, hence the name.The following equations were used to design the windchime.
With units in centimeters, f becomes the frequency in Hz of the primary resonance of the chime. V is the velocity of sound in the metal in Meters per Second, I is the inside diameter in cm, O is the outside diameter in cm. L is the length in cm. k was just separated out of the main equation for clarity.
For determining the frequency of all the chimes, one needs to take into account that there are 12 logarithmically spaced notes on the musical scale. The formula for determining the frequency is.
Original Build Date:01-15-2006
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