Pneumatic Organ

Project Sponsors

Unitarian Universalist Society of Bangor

120 Park Street
Bangor, ME 04401
(207) 947-7009

Point of Contact

Main Point of Contact

Samuel McDonald –

Group Members

Aaron Dallman –

Evan Hanzl –

Justin Willis –


Weekly Updates

Video of final testing 


The group met to draft a team contract. This contract will be our reference point for all future conflict resolution within our group, and was signed by all members. Next we assigned the initial round of research for the group. Topics covered included a glossary of terminology, common failure modes, existing schematics, and information on the manufacturer, E.W. Lane. A main point of contact was assigned for the team (Samuel McDonald) and an initial contact email was sent to the client. Finally, the group presented all current research so all members could remain informed.


The team has been preparing for our initial contact with the clients at the Unitarian Universalist Society of Bangor (UUSB), and our first look inside the organ itself. After our brief first look, the team sat down with Chris Packard, John Arimond, and Eric Olson along with the project adviser Keith  Berube to discuss next steps. It was understood by all parties that communication is to be a primary focus for the duration of this project. A maintenance history of the organ was discussed, as well as a schedule for future visits to the church. It was decided that the group will have access to the organ for diagnostics and repairs on Tuesday evenings.


At this week’s adviser meeting, the group discussed some of the issues already identified within the instrument. The main priority seems to be repairing the “stops” of the organ, many of which have become broken. Also discussed were the hazards associated with working within the organ, including dust and lead contamination. The group may decide to clean the dust from within the organ before proceeding with the diagnostics. An ultrasonic leak detector which the group may have access to was discussed, as well as some vibration analysis equipment from Professor Karen Horton.


This week was Fall break, and the group did not meet. Instead, the group continued to work on preliminary presentations for capstone class. Sam and Justin discussed pneumatic pipe stops, while Evan and Aaron presented on the history of the organ and basic operation.


This week the group returned to the church for the first time since the initial client meeting. The focus of this meeting was primarily on identifying non-functioning pipes and the root cause of these issues. During the investigation, some pipes were re-attached and made functional. Until a new glue is proposed and selected however, these fixes will not be permanent. Focus has now shifted to creating a detailed diagram of the operation of the organ, as well as writing the first interim report of the semester. Next scheduled  meeting at UUSB will be Tuesday, October 24th.


This week the group discussed zephyr skin, a kind of thin leather that is used throughout the organ for seals and bellows which the group has identified to be failing. This material will be difficult to source, and the only supplier the group has found is located in Germany. The group continued to discuss the use of traditional “fish glue” to repair the pipes vs. updating to a modern adhesive such as epoxy. A meeting was scheduled at the site of the organ with Mr. David Wallace and his son, who are specialists in the construction, renovation, and restoration of organs based out of Gorham, Maine. This will be an opportunity for the group to seek advise from a professional in the industry and seek new solutions for this project


Strong winds and heavy rainfall caused power outages this week and prevented the group from getting together for the three weekly scheduled meetings. Instead, the group continued to focus on individual research.


This week’s on site visit with the Wallace Company was extremely informative for the group. We discussed methods and approaches commonly used to repair these instruments, tooling used in the industry, adhesives and leathers, and a means to access some sections of the organ previously unreachable. According to Mr. Wallace, the original fish glue adhesive used in repairing the organ will be the best option. He also offered his company as a third-party means of ordering supplies otherwise limited to industry professionals. The group must now begin the process of ordering our first batch of supplies to begin testing solution processes. 

Our next visit to the organ is now focused on the operation of the stop action of the organ. Many of these stops have failed open, meaning that multiple ranks of pipes will always play and can not be selectively closed. 


The group has begun to focus heavily on the stops of the organ. These stops restrict the flow of pressurized air into the ranks of pipes, allowing one key to play multiple pipes of the same pitch in different octaves, with varying tonal qualities. Many of the fourteen stops in this organ have failed, leaving some stuck open and others completely non-functional. One proposed solution includes removing the current assemblies which rely on leather bellows to actuate a seal on the windchest with linear actuators or solenoids. Another possibility is to replace the current leather membrane which is very difficult to obtain with a synthetic material with similar properties. The final proposed option is to source the original material and do a historic restoration. The group is gathering information and performing tests on all options before the final decisions are made and the repairs can begin.


The team has begun exploring various options to purchase materials for the repair phase of this project. Most manufacturers of zephyr skin leather will only accept professional companies as customers and finding a source for this material will prove difficult. At the organ, the team measured the force required to actuate the stops within the wind-chest, as well as the amount of deflection (movement) required to close the valve and create a seal. The team also decided to investigate the blower used to supply the organ with air. Aside from some dust and worn brushes, the “ORGO-BLO” motor (made in 1915) was in remarkably good shape.


The team determined a more accurate method to measure the actuation force of the stops than the spring used previously. A pressure transducer was borrowed from the MET department and used to measure the pressure within the windchest. Upon testing the organ, this pressure was measured to be roughly four inches of water column, which is equivalent to about 0.14 psi. Any synthetic material selected to replace zephyr skin will need to deflect quite easily under low pressures. 


The team would like to test the adhesive properties of the fish glue purchased by Aaron. After a calculation based on known values for this glue, the team determined that the lead tubes will fail long before the glue in this test, which can (theoretically) support 1,570 pounds of force, or roughly 1.4 miles of lead tubing. The group also worked on the second interim report of the semester. 


This week the team began to finalize the second interim report. Included in this report is data from the calibration of the pressure transducer and various pressures recorded from within the organ. 

Winter Break


After revising Interim Report 2 over break, the team returned and hit the ground running. Meeting on the first day of classes, the team finalized all revisions and submitted the final draft to the project adviser and clients. The team then began to draft a list of final deliverables and write a client contract to be signed by all involved parties. This contract defines primary goals which must be completed for the project to be considered “successful” as well as secondary goals which the team will strive to complete in addition to all primary conditions. Team 7 has also begun the process of ordering materials which will be required throughout the course of this repair; namely the silicone rubber sheets and aluminum stock used as clamping material. 


After revising the client contract the team sent a draft to the clients along with an initial cost estimate for the project. The team was encouraged by Professor Berube to establish project milestones for the remaining tasks on the timeline. Purchase orders for the aluminum sheet were approved and the team plans to cut the stop faceplates from this sheet next week. The group was tasked with further investigating the chemical aging properties of silicone rubber. 


The aluminum was delivered by Bangor Steel. Sam will use his connections at the Advanced Structures and Composites Center to get free time on the waterjet to cut the stop block faceplates. The final contract revision was signed by the team and presented to the clients for final approval and signing. The group is seeking methods to cycle test the silicone rubber and was advised to consult with the “soft robots” capstone team.


The team removed the intermediate windchest found to be causing key failures on the swell side of the organ. As expected, several sections of the leather membrane on this intermediate windchest were ripped and leaking air. Before removal, Team 7 carefully marked all connecting tubes with numbers in the event that some fell out of their seatings during the process. Team 7 plans to replace the leather membrane with a silicone rubber sheet as discussed previously in a similar method as with the stops. The team meeting raised concerns about the different materials and their thermal expansion coefficients, but after some quick analysis it was found that the aluminum faceplate used to clamp the rubber sheet would only expand by 38 thousandths of an inch over the full length of the board. 


The removed windchest was thoroughly measured and translated to a spreadsheet, and subsequently a SolidWorks 3D model of the sheet. These will be used to replicate the board rather than simply replacing the original, cracked board. 


A new source of Pneumatic leather has been identified, meaning that the team can refocus on a more historic restoration than otherwise thought to be possible. This leather is rather expensive and somewhat thicker than the original sheets, but will provide a more accurate restoration. The silicone may still be installed as a trial stop block to test the efficacy of this material, but if this is done the team will leave UUSB with a pre-fabricated block made with leather and detailed instructions on how to replace it should they desire. This must be further discussed with the clients. 


Team 7 spent much of this week preparing for Interim Report 3. This penultimate report includes detailed explanations and diagrams of the build process thus far, as well as an updated budget to account for the newly purchased leather. 

Spring Break


The build has begun and the first intermediate windchest has been constructed. The team carefully laid out hole positions and drilled holes allowing space for the lead tubes as well as space for the leather membrane to expand. The team also tested the fish glue purchased earlier on the new leather by fabricating a single stop block. This will be tested in the organ soon. The leather bonds well to the wood being used, and the glue sets quickly, meaning we will not need to use faceplates in the installation.


The group has encountered some minor setbacks with regards to the windchest. The holes drilled in the board were slightly oversized, and the walls between holes were thinner than the group was comfortable with. A new drill bit was ordered, and a new board was quickly fabricated. The second time this process went much more quickly and the board was finished the day after the new materials arrived. Next steps will include gluing the leather strips on to the sheet, as well as the cardboard contacting surfaces and installing this first board within the windchest. When the team has confirmation that everything is working as expected, we will fabricate and replace the stop blocks.


Leather was glued to the surface of the board. Surfaces were prepared by lightly sanding the wood, then hide glue was spread over the full surface of the board. The leather was draped over the length of the board in sections. A line of glue connected the seams between sections of leather, and the board was clamped to another sheet of the same length and placed under weights. After the glue had set, the small cardboard pads that act as the actuation surfaces were glued to the surface of the leather. 


The first of the intermediate windchests has been installed within the organ. Initially, the board was installed too tight, and every note on the organ would play when it was powered on, but by making some simple adjustments the team was able to fix this easily. After installing the board and re-gluing each lead pipe within the organ, it was once again powered up and tested. Several notes still did not sound, but the adjustment to fix this was again very simple. Each hole on the intermediate windchest and each air supply tube is drilled with a small pressure relief hole. To increase the pressure within the board, the relief holes on the notes that were not sounding simply had to be plugged. Some notes in the higher register still will not sound, and the team hypothesizes that the leather is too tight over these sections. This will be addressed at a later date, by artificially stressing these sections of leather to increase their range of motion. 


The second board has been fabricated and installed. Rather than fabricating a new board, the team determined that the board being replaced was in good condition, and simply needed a new layer of leather. The ripped layer was removed, and the board was planed by 0.010″ allowing the team to glue a new surface of leather. This process was exactly the same as that followed on the first board, except the team this time used small weights on each of the holes to leave a depression in the leather to avoid problems identified with the first board. The second board came out perfectly, and was installed in the organ quickly and easily. In re-investigating the original board, it was found that some of the supply tubes were crimped or otherwise restricted. This may be the cause of the failing notes, and plans are in place to address this crimping and prevent it in the future. 


The team is now in the final stages of the repair process. This past week the left side stops were all fully installed and tested, and work has begun on the right side stops. The team decided to replace the left board with a newly fabricated one rather than patching over 5 “bubbles” that were stretched too thin in the leather. Now the team must continue gluing pipes in and prepare for next week’s final presentation on the University of Maine campus. Any final adjustments can be made next week or the following week during finals. 


Project Description

The Mechanical Engineering Technology faculty was approached by the Bangor Universalist Unitarian church with a proposal to repair  their tubular-pneumatic pipe organ. This instrument was built by E.W. Lane in the late 1800’s and presents some unique challenges for the team to approach. Goals for this project include first learning about this instrument and its history, consulting industry professionals on proper repair approaches, diagnosing problems, and proposing a final plan of action. 

Team Biographies

Aaron Dallman

Aaron originally started at the university of Maine in 2009 as a civil engineering major. Through multiple years and breaks from the university made his way through the departments of mechanical engineering, and engineering physics before landing and settling into the major of mechanical engineering technologies. Just shy of 30 and being married as well as a homeowner he is the resident cranky old guy of the group. Aaron is also an automotive diagnostician &  mechanic, welder, and all around general fabricator. Aaron is a proud brother of the Alpha Delta service oriented fraternity. He is expected to graduate in May of 2019.

Evan Hanzl

Evan is a fourth year MET student from Lebanon, Maine with a background in musical theory and performance. He initially enrolled in the Mechanical Engineering department but decided to move to a more hands on field. After switching majors he declared a minor in Business Management to further his education. Evan has been fortunate enough to receive work experience with his family’s business as tooling vendors as well as an internship in the development lab at Laars Heating Systems testing new control systems on industrial boilers and water heaters. He performed various tasks such as wiring high voltage panels, custom sheet metal work and machining, calibrating equipment, graphing and interpreting data, programming PLCs and connecting gas/water lines. He hopes to work as a manufacturing engineer and eventually run his own business after graduating in 2018.

Sam McDonald

Samuel McDonald, a mechanical engineering technology student, transferred to the University of Maine in fall 2016 after completing an Associate’s degree in Pre-Engineering at Southern Maine Community College. He is currently employed by the UMaine Advanced Structures and Composites Center. He primarily uses ASTM standards to fabricate, test and analyze composite materials. His projects of involve vacuum infusions of neat resin panels, infusing fiberglass reinforced plastic composites, carbon fiber reinforced plastic composites, and full-scale composite structural members. Sam has always had a fascination with aircraft and wishes to either fly military aircraft or work in the aerospace industry upon graduation.

Justin Willis

Justin is a senior MET student from the “Down East” town of Penobscot, ME. Justin enrolled in the Mechanical Engineering Technology degree after graduating from George Stevens Academy in Blue Hill, ME. Since enrolling at the university, Justin has worked as an intern in the research engineering department of Maine Maritime Academy and at the composite manufacturer Compotech Inc. During the school year, Justin also tutors Technical Physics and Calculus courses for the University of Maine as a College Reading and Learning Association certified Advanced Tutor. Justin also provides homework help and study skills tutoring to students at Old Town High School and Leonard Middle School, free of charge through a nonprofit program he began at New Life Old Town church. Justin hopes to teach physics, engineering, or industrial technology classes at the high school or college level after he is expected to graduate in May 2018.