How to Design Organ Case Pipes

This post is about my use of design technology that assisted me in building several mechanical action pipe organs as an independent pipe organ builder. I am going to use the original design objects that I used to build the organ described in my previous post here as examples. That organ was designed as a new instrument built around a core set of late nineteenth century artifacts. The challenge lay in creating a valid functional design built around those artifacts that were specifically three sets of discarded organ pipes still valuable for their great tonal beauty.

An interesting aspect of that pipe organ, and all subsequent that I built, was the use of technology to help successfully achieve the final results. It must be apparent from my previous posts that I have a strong background in computer aided design and manufacturing technologies.

I wrote several computer programs for pipe organ design shortly before I began building pipe organs as an independent builder. The programs automated and simplified tasks that were particularly challenging by creating useful geometry in a computer aided design and drafting program.

Pipe groupings that make up the front of an organ case are a traditional part of early organ building, and one of the tasks I simplified by using a purpose written computer program was to accurately model the front pipes that would form part of the organ case design. The front case pipe grouping for an organ I built is represented here in both its computer form, and in a photo of the actual instrument.

The image at the top of this post is a screen capture of an organ case pipe design program I wrote using a Java development tool called BlueJ. I used BlueJ to program in Java while briefly working at a small private liberal arts college that followed my stint as an organ builder, and I found myself in a position there to learn an object oriented computer programming language. The original organ case design program was written in a procedural programming language, and I used the opportunity to rewrite one of my organ design programs in a new programming language paradigm to significantly lessen the learning curve.

The organ case pipe design program like the other programs I wrote created a script file of drawing commands that produced accurate geometry when read into a computer aided design program. The result of the case pipe design program was a set of twenty-five accurately dimensioned pipes interpolated from three user input octave dimensions that determined the scale of the set. The interpolated values were accurately computed using geometric progressions.

The pipe geometry created in the computer aided design program could then be used and edited to create a set of pipe groupings visually appropriate to the intended organ case design. I hope the screen images included here adequately demonstrate this process without going into any further discussion that would be well outside the scope of this post.

Windchest design with nested pipes in plan or top view represented another major design challenge that I simplified by writing a set of rule-based winchest design and pipe nesting programs. A screen shot of the windchest design in plan view for the first organ I built is shown below. The rectangles represent the plan view outlines of the wood organ pipes, and the outer circles represent the plan view outlines of the metal organ pipes. The inner circles represent special devices called slider seals. An associated computer program would calculate the appropriately sized slider seal based on the wind requirement of its corresponding pipe, and represent it in the drawing as a uniquely colored circle.

Reuse and Repurpose

My workshop is located in a building peripherally considered to be part of the Northeast Minneapolis Arts Association. Each spring the association hosts an open studio art tour know as Art-A-Whirl where the largest concentration of activity can usually be found at the Northrup King Building. It struck me when walking through the Northrup King Building not long ago how many artists reuse old material in their new work, and because of this I thought about the first organ I built as an independent pipe organ builder.

That organ came about when I was asked if I would be interested in the remains of an early twentieth-century pipe organ that were removed from a church in northern Illinois. What I found useful in that material were three sets of pipes that could be used to make a late-baroque cabinet organ if revoiced and added to by new pipe ranks that would provide the new organ with a complete and well-rounded set of tonal resources.

I therefore set about designing a one-manual mechanical action organ built around a specification that included the three older sets of pipes along with two new sets that completed a unified tonal plenum based on the late baroque style common to southern German organ building of that period. The new organ design included a new slider windchest, new wind supply, new casework of solid walnut, and a new mechanical action to directly connect each key to its corresponding pipe valve, all produced in my shop.

I contracted out the keyboard and metal pipes to respective firms who did work in reproducing early organ material to stay true to the historical nature of the instrument. Carvings were done by a local artisan whose normal business was furniture refinishing.

I would not have originally intended to build an organ using older material had it not been available for free, although organs have been built this way for centuries. Obviously though, there are many artisans who use older artifacts in their work, and base much of it on this principle of reuse and repurpose.