Wind Chimes

tubular-bells

Tubular Bells  

  

Tubing

 

If you suspend a piece of tubing by pinching it lightly between the thumb and finger of one hand, and strike it with the other hand, it will ring.  If you adjust your pinch point up or down, and strike the tube each time you do so, you will notice that:  1) the tone will get higher or lower, and 2) the time of audible resonation will increase or decrease.   

 

When you get to the sweet spot, mark your tube with a pencil.  If you measure how far the sweet spot is from the top, you will find that it is about 22.5% of the total length (22.42% actually).  You will find that the sweet spot on any given tube will be about 22.5% of the length.  (There are secondary sweet spots closer to the ends of the tubes, which might also appeal to you.  Try finding them.)

 

If you strike the tube with different materials, such as steel and rubber, you will hear a different tone.  Therefore, use the same material for this purpose as will be used in the finished product.

 

In two tubes of the same length and diameter, the one with the thicker wall will have the higher pitch.  In other words, you can achieve the same sound with a shorter, thinner walled tube.  Thin walled tubing costs less.  However, if the tubing is too thin, it will flail around in a strong breeze.

 

My recommendation for a first set of chimes is to use aluminum tubing with a 20mm diameter and a 1mm wall.  This will provide a pleasing sound at a reasonable cost.  Scrap aluminum electrical conduit or old tent poles will also work, and might be found for free.   

 

Tubing is readily available in eight foot lengths, which is 2440mm.  One length is enough to make a six tube set of chimes, cut so:  350mm, 370mm, 390mm, 410mm, 430mm, 450mm.  Smaller (5mm to 10mm) increments will yield a thrumming, resonant sound.

 

Aluminum tubing can be easily cut with a coarse hack saw blade.  A fine blade will tend to plug up.  Clean up any uneven or ragged spots with a coarse file.  If the file plugs up, clean the teeth with a wire brush.  (A Nicholson Magi-Cut File is well suited for this purpose.)

 

Before drilling 4mm (or larger, if using heavy cord) holes for hanging a tube, remember that you want to preserve the sweet spot.  The sweet spot must be at the top edge of your finished hole.  Therefore, to drill a 4mm hole, you must center your bit 2mm below the sweet spot.  (A smaller hole is difficult to thread.)   

 

To prevent the drill bit from wandering, make a dimple at your centre mark.  Do this by putting the point of a (concrete) nail on the mark and then striking it lightly with a hammer.

 

To remove the sharp edges from a drilled hole, take a bigger bit and turn it by hand in the hole.  Burrs on the inside of the tube can be removed with a rattail file or a dowel wrapped with coarse sand paper (40 grit or 60 grit).

 

Old aluminum tubing can be cleaned up by using coarse sand paper.  Finer sand paper can be used, but it will take more effort.  Sand paper will score the surface easily, and you can create decorative patterns with little trouble.  You can also easily add patterns by using a wire brush.

 

 

 

The Roof, The Clapper, and The Pendant

  

These can be of any materials you like.  An old aluminum pot lid will work as well as oak for the roof; an old hockey puck will serve as well as cedar for the clapper; an old serving spoon is as good as hickory for the pendant.

 

To lay out the hanging points on the roof, start by choosing the size of the clapper.  The clapper will be spaced 4mm from the tubes.

 

Using a hockey puck (76mm diameter) as a clapper, the primary layout circle will have a radius of:  38mm + 4mm + 10mm = 52mm.  This will yield a circle running through the center of 20mm tubes.

 

Bear in mind that the finished layout will in fact be a hexagon, the sides of which will run through the center of the 20mm tubes.    

 

Draw a Center Line across the length of a sheet of paper.  From the Middle of this line, use a compass to draw Circle One with a radius of 52mm.  Draw Circle Two and Circle Three, centered on the points of intersection of Circle One and the Center Line.  Draw Circles Four, Five, Six, and Seven, centered on the points of intersection of Circles One and Two, and Circles One and Three.

 

Draw lines tangential to the tops and bottoms of Circles One, Two, and Three.  Draw lines tangential to the other Circles and Circle One. 

 

A hexagon is drawn, the corners of which are slightly beyond the intersection points of Circle One and the other Circles.  This placement is necessary to ensure the air space between the clapper and the tubes.

 

On the Center Line, mark points 20mm left and right from the Middle mark.  These three points, and the points of intersection of the hexagon lines, will be drilled with holes of 4mm diameter.

 

On the clapper, lay out three holes on a center line, at the Middle and 20 mm left and right of the Middle, as was done with the roof.  These points will be drilled with 4mm holes.

 

On the pendant, drill one 4mm hole for tying off.  (Or, drill a second hole near the bottom, and tie the cord so it hangs below. It will lay on the sides of the pendant, but may be considered a design feature.)

 

 

 

Lacing the Tubes to the Roof

 

Use Braided Mason’s Twine for lacing.  Nylon or polyester will do.  Long boot laces, or cord salvaged from curtains or blinds, can also serve the purpose.  (Adjust the size of your drilled holes according to the cord size.  Better to have holes a little bit large than a little bit small.)

 

Allow for a 30mm airspace between the tops of the tubes and the Roof.  Calculate the length of twine required to suspend the longest tube, including a full wrap across the side of the hexagon above.  (Allow about 400mm per tube X 6 = about 2400mm.  Add some for knotting, and call it 3 meters.)            

 

When lacing the tubes, do a full wrap around each side between the tubes.  This will provide the friction necessary to prevent the heavier tubes from sagging and pulling the lighter tubes up.  You can adjust the tube heights afterwards with a little plucking at the wraps around the hexagon.  Tie a knot.  The surplus cord may be tucked under the wraps around the hexagon.  (Searing a knot with a flame will ensure that it will not slip.)  

 

To suspend the chimes, feed the ends of a piece of twine Down through the holes in the roof that are 20mm left and right of Center, then pull both ends Up through the center.  Knot, and cut off the surplus.  Your may want to add a key ring at the end to resist wearing at the point of suspension.

 

 

 

Lacing the Clapper and Pendant

 

Feed the ends of a piece of twine Up through the roof holes that are 20mm left and right of center, and then back Down through the center.  Then feed both ends together Down through the center of the clapper.  Feed one end back Up through each of the holes that are 20mm left and right of center.  Again, feed both ends together Down through the center hole.  The clapper will stay at whatever height it is set at, and can be adjusted for height with a little plucking.

 

The best location for the clapper, in terms of sound production, is close to the bottom of the tubes.  That is why having the tube bottoms about level is a desirable design feature.  Experiment to find the best location for the bottom of each tube.

 

Tie off the Pendant and trim the twine.

 

Hang your chimes and enjoy them.

 

Note One:  Oak or cedar will weather far better than birch or spruce.  Any EXTERIOR grade plywood will weather well, especially that used for signs.  PURE Tung Oil is a good, simple, protective finish that is also food safe.  

 

Note Two:  Copper tubing sounds dull.  Commercial and Industrial electricians sometimes throw out or recycle scrap aluminum conduit.  Offer to make a set in exchange for access to the pile, and you may have a lifetime supply of tubing in a hurry.

 

 

For more information, go to:

Samuel (Tubing Supply)

 

An Engineering Approach to Wind Chime Design

 

Chuck’s Chimes

 

Standing Waves and Musical Instruments

 

Physics of Sound and Music:  Instruction and Problems

 

Making Wind Chimes (by Jim Kirkpatrick)

 


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