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Making
the Pipes
Most
of the page below was written some months ago, just after I finished rough-tuning
the pipes. (I haven't worked on them since, as I have been working on
the cabinetry and on the windchests) Several people have written to me
about voicing the pipes, asking about my method for determining pipe lengths,
or other key parameters. I wish I could say that I have all the answers,
but I simply don't. I started with the general guidance from Audsley's
(and others') books and built one pipe. I measured its pitch, and scaled
the rest of my set from that one, varying length, width, depth, cut-up,
wood thickness -- everything. I made each pipe extra-long, and cut it
"to pitch." The only place I got in trouble is where I deviated
from this plan: the bottom octave, I did not scale width and depth, and
the pipes get progressively weaker and more "breathy" as I approach
low-C.
I made
the decision to set aside voicing (and generally fussing with) the pipes
until after I had the windchests hooked up and working, so that, when
I got a satisfactory result from a particular pipe, I'd be DONE with it.
That bit of work is coming up, probably later this Spring. (Spring 2005)
I have
signed up for woodworking at "Paly High" again this quarter,
and will be using the time to build the base upon which the organ will
sit, and which will contain the blower and the pressure regulator.
-A,
12/28/05
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Part of the family of pipes. The organ will have one rank of open
pipes. All are built to the same proportion -- scaled for each pipe.
Even the wood thickness is scaled.
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The feet are poplar dowels, drilled and beveled.
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Pipe detail showing a little of the construction. The flat pieces
at the bottom are the caps, shown turned over, so you can
see the air passage inside. They will be held in place with 2 wood
screws each.
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Planing the wood for the pipes. The face is maple; the sides are
clear redwood. As it is the air column that vibrates, not the wood,
the choice of wood is less important than in other instruments.
Audsley suggests hardwood for the face and softwood for the sides
and back.
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The air enters the pipe from the bottom. The passages are formed
by gluing a block to the bottom of the pipe and milling the shape
shown.
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After milling
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Making the cap
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Milling the bevel for the mouth.
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Preparing to glue the face on the pipe, I first sanded
them flat. I'm not really jointing them here -- I'm using the flatness
of the jointer table to hold the 2 sheets of sandpaper are taped
to the table. That way, I can get the face of the pipe really flat
for gluing.
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Now
... where to put the cap?
Fifty thousandths below the bottom of the mouth. Precise, accurate,
carefully executed total wild guess.
Actually,
I clamped the pipe together first, and made it speak. Several dimensions
were tested -- 0.050" worked best.
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Next,
a temporary stop-block is clamped to the pipe, where the cap will
eventually go. Here I'm positioning it precisely.
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Temporary
stop-block in place
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Next the pipe face is aligned to the stop block and glued in place.
Then the stop block is removed. (as it has been in this photo)
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Cut
the face to length
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The base of the pipe is drilled to accept the foot. Notice the screw
and washer. These provide a "throttle" to adjust the airflow:
back the screw out and it occludes the air passage, run it in, and
the air flow increases.
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The washers are soft-soldered to the screws by means of a jig to
insure concentricity.
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Soldering the washer in place. The aluminum jig assures concentricity
of the washer to the threads.
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A drilling jig insures that the screw-hole will be concentric with
the hole for the pipe foot.
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Drilling ...
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... and tapping the hole for the "throttle" screw.
I found that the machine-screw threads in the poplar provide enough
drag to insure the screw doesn't back out on its own.
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Installing the screw
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Drilling the cap. A drill inserted in the first hole insures
alignment while the second hole is drilled.
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