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

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.

The feet are poplar dowels, drilled and beveled.


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.



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.



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.

After milling



Making the cap

Milling the bevel for the mouth.



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.



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.


Next, a temporary stop-block is clamped to the pipe, where the cap will eventually go. Here I'm positioning it precisely.


Temporary stop-block in place



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)



Cut the face to length



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.

The washers are soft-soldered to the screws by means of a jig to insure concentricity.



Soldering the washer in place. The aluminum jig assures concentricity of the washer to the threads.

A drilling jig insures that the screw-hole will be concentric with the hole for the pipe foot.

Drilling ...




... 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.

Installing the screw



Drilling the cap. A drill inserted in the first hole insures alignment while the second hole is drilled.

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