Organ Blower builds vital air pressure

Renewed Air Supply for the Spreckels Organ: the Newly Rebuilt Blower – Gary Allard, 2020

(September, 2020) A steady stream of pressurized air is necessary not only to sound the pipes of the Spreckels Organ, but also to activate the vast array of mechanics that direct which pipes to sound, and when. To drive air into the organ’s wind chests, a blower consisting of a motor to turn the axle and fan blades to spin and gather the air into a duct that leads upstairs to the wind chests.

In 2018 the motor on the blower shorted out after decades of faultless performance (see story below). There followed a six-week delay as the motor was removed, repaired, and re-installed. Just in time for Thanksgiving and the holidays, the Spreckels Organ was back in business. But … the blower was living on borrowed time.

As the motor was removed for repair, an inspection of the blower mechanism, consisting of three gigantic centrifugal fans as old as the motor, revealed sufficient wear to require replacement. Several vanes had developed significant cracks, and the surface of the aluminum blades was pitted after so many years of service. The City of San Diego, as owner of the organ, was ready to okay and pay for this rare procedure.

To create and install replacement blades isn’t an easy task. Like so much else about pipe organs, the blower’s repair is a unique specialty. The Curatorial team contacted Bob Otey of Auburn, Washington, who specializes in building and restoring organ blowers.

Here’s a link to a full set of photos:

Originally from Pennsylvania, Bob worked as a tool and die maker for the aircraft industry in the Seattle area. After some 20 years, he decided to venture out on his own. Due to his love of organ music, he soon found a niche market in supporting pipe organs around the country and beyond. He has restored and repaired organ blowers in Mexico, Australia, and England as well as the U.S. and Canada.

Bob appreciated the foresight of the curatorial team for inspecting the blades at the time of the blower’s motor failure. The decision to replace them now he sees as priudent. It’s common, even at prestigious performance venues and religious institutions with grand organs, for the hardworking blower mechanism to be ignored. While everyone knows the importance of keeping a fine organs in tune, many overlook the mechanical demands of the organ blower, since blowers customarily do their job without special attention for years. A sudden failure, if unanticipated, can be surprisingly inconvenient! By the time his clients contact Bob, their needs usually range from significant repairs to total failure. In the case of the Spreckels Organ, the heightened expense of a sudden or total failure of the fan blades was averted.

The blower in the basement of the Organ Pavilion consists of three large centrifugal fans connected to a common shaft driven by the motor. The original fans were made of aluminum but the new fans are made of heavier galvanized steel that generates more air volume going to the wind chests.. The new fan blades are also an inch longer than the originals, again providing additional air to the wind chests. The fans were custom made by Bob in his shop using a laser-cutting lathe to ensure precision. The first stage (innermost) fan blades are 31 x 2 inches, while the second and third stage fan blades are both 38 x 3.5 inches in size. Not your average household fan! The old blower produced about 5,000 cubic feet per minute of air, but a calculation of the new blower’s output has not yet been made.

Each fan stage is separated by a steel plate. As each stage is installed, the fan’s balancing is checked before inserting the plate and proceeding to the next stage. The fans were balanced in Bob’s shop prior to shipping, but it is possible that being bumped around during shipping as well as imperfections in the existing shaft, motor, foundation, or other onsite issues can cause a balanced fan to go out of balance. Thus, in-situ balancing is always performed before closing up the blower and installing the new housing.  

A strobe light identifies any imbalances while the fan is running. Adjustments are made by adding miniscule weights to specific blades to bring the fan back into balance.

The Spreckels Organ’s blower is at least 75 years old, maybe more. Bob predicts the now-finished rebuild could keep the organ breathing smoothly for the next hundred years or more! Who knows? One thing is for sure – its work will contribute to many more years of beautiful music to audiences here in San Diego and worldwide via the internet.

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Fall, 2018 – After Decades, the Blower Goes

During the Holiday Season of 2018, the Society expressed gratitude to the organ curatorial team and the City of San Diego’s Parks & Recreation Department in the quarterly StopTab for “their fast and efficient work to repair the 70-plus year old Spencer Turbine after it shorted out” on September 26, 2018.

To fix it, the 1500-pound blower had to be disconnected and removed from the Pavilion, which was accomplished in October by the team at San Diego’s Sloan Electric.

The motor was re-wound and the apparatus reconditioned. At the Pavilion, new electrical lines were placed to fully support the 25 horsepower capacity that the reconditioned blower would offer. On November 8, 2018 the repaired equipment was re-installed and tested — in time for a concert the following Sunday, as well as all the holiday concerts soon to come.

As the motor was being rebuilt, Sunday audiences were treated to tensive “show and tell” presentation on how the Spreckels organ makes its music.

This six-week hiatus was the longest period in living memory that the organ had been silent in the park — until 2020 and the Covid-19 pandemic shut down concerts after March 15.

With a close-up inspection of the disabled blower, it was clear that there would need to be more work arranged for it. The impeller blades on the blower, while serviceable, showed significant wear after about 70 years, so plans were made to replace them as soon as was practical. As with so much else, who could have known that “soon” would be a period of almost two years, and that the scheduling of the work would not be squeezed due to live concerts?

  • Ross Porter, 2020
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