Simplified making of double bourdon melody pipes page 3.

By BOB ESSEX

The Stoppers.
The Stoppers are cut from 10 mm. thick hardwood and trimmed to about 1 mm. less than the internal dimensions of each pipe. A  6 mm. hole is drilled through the centre and a short length of 6 mm. dowel is glued in place.   The edges of the stoppers are chamfered and rounded slightly before the small rectangle of chamois leather is glued, with Copydex  -  only to the bottom surface of the caps, not to the sides.

Round knobs, drilled to take the 6 mm. dowel are glued on to finish the stoppers.  I use the small turned-wooden polished beads recovered from those beaded car seat covers which seem to be no longer fashionable.  

Cutting and tuning.
If the dimensions of the pipes on the spreadsheet have been adhered to, the pipes will all be rather longer than they need be to produce the desired note.
The double pipes should be tuned one side at a time by covering the mouth of the opposite side.  The upper lips should be temporarily held with an elastic band in the most favourable position to produce the best sound.  The pipes can then be cut to length so that the stoppers are approximately 10 mm. recessed into the top of the pipes.  The upper lips are secured to the body of the pipe using Copydex. Pipes should always be voiced and tuned on the actual organ wind.  Blowing by mouth is a useful test, but not accurate enough for anything but approximate tuning.

Celeste versus Unda Maris.
If both sides of the double pipe are tuned exactly the same, they will sound the same note together, but rather louder than a single pipe.  If one of the pipes is then tuned very slightly sharp, by pressing the stopper in a tiny amount, the pipe will then give a hollow, wavering note with an ethereal quality.  This tuning is called Celeste, meaning “heavenly”.
A distinct “beat” is heard, the speed of which depends on how much variation there is between the tuning of the pipes.  A typical Celeste should have a beat of about half to a quarter of a second.

                             By tuning one of the pipes slightly flat, instead of sharp, the sound produced is called Unda Maris, meaning “Sea Waves”.  Melody pipes are usually tuned Celeste.  Unda Maris tuning is usually used for deeper Cello pipes in the accompaniment or the bass section of the organ.

Upper lips.
Upper lips made from similar hardwood to the caps.  These are about 40 mm. long and the same width as the blocks.  They are bevelled to form a knife-edge.   This edge should not be too sharp, but rounded slightly with sandpaper.  It is most important to give a fine polished finish to the caps, blocks and upper lips to get the best possible sound from the pipes.

Bob Essex  3/2005  Thanks to Bob for sending this article in to the A.O.B.G.

Caps and gaskets.
Caps should be cut from hardwood. each is 30 mm high and cut to the overall width of the pipe.  The top surface forming the upper lip has a 45-degree bevel on its outer edge. The cap is then placed on a sheet of thin cardboard to mark out the size of the gasket, which is cut with a craft knife. Cereal-packet cardboard is just about the right thickness   The completed caps and gaskets are glued to the pipe body using Copydex.  This is latex adhesive which forms a semi-permanent bond, but the caps can be easily removed if necessary.  It sticks easily to the varnished surface of the pipe-body.