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Deburring/Finishing

Big Gun Repair

Above: In 1945, the submarine had a 5-in., 25-caliber wet mount gun for shore bombardment and anti-ship combat, along with several smaller guns.

This story was originally published here as a web exclusive and updated for the July/August 2016 Top WebEx issue.

Restorer turns to flexible hones to repair WWII submarine’s big gun

July/August 2016 - Restoration expert Rich Pekelney painstakingly restores historical maritime vessels ravaged by the sea. Decades of submersion in a corrosive environment rrequires Pekelney to perform a combination of historical research, exhaustive documentation, parts scavenging, and metalworking and coating.

Such was the case for the USS Pampanito, a World War II submarine museum and memorial on Fisherman’s Wharf in San Francisco that hosts over 100,000 visitors a year. The boat is owned and operated by the Maritime Park Association, a nonprofit that has spent the past 34 years engaging in a meticulous effort to restore the Balao-class fleet submarine to the height of its peak configuration during the war.

“The primary goals are to get it as close to summer 1945 condition as we can, while at the same time preserving as much of the historic fabric as possible,” says Pekelney, who in addition to being a volunteer restoration expert is also a member of the board of trustees of the Maritime Park Association. “We owe it to future generations to preserve our history and USS Pampanito is part of the history of the submarines.”

FFJ 07816 gun image1

These are rare weapons, with only 11 in varying states of preservation surviving today.

According to Pekelney, when USS Pampanito was donated to the museum by the Navy and opened in 1981, there were no guns onboard. However, in 1945 the submarine had a 5-in., 25-caliber wet mount gun for shore bombardment and anti-ship combat, along with several other smaller guns.

As part of the restoration effort, the Maritime Park Association was able to acquire a stripped version of the same gun from the Navy that bad been originally used on USS Piranha. These are rare weapons, with only 11 in varying states of preservation surviving today.

The gun was in disrepair, de-milled, rusty, vandalized and not properly assembled. It lacked a variety of parts, including covers, bolts, seats, gears, handles, fittings.

Restorers set out to preserve historical accuracy with particular car to reinstating the weapon’s training (movement left/right) and elevating (movement up/down) capabilities.

During its idle 75 years, the training and elevating gears and other components were completely seized and frozen due to paint in the bearings, hard old grease, dirt, bad gear mesh, corrosion and possible material creep.

FFJ 07816 gun image2

Bronze sleeve bearings had to be cleaned by a sanding/honing process and in some cases small amounts of material were removed to allow smooth operation.

“This gun, as far as we can tell, has not been operated or trained or elevated in decades—probably since the time of war,” says Pekelney.

Because the gun was designed to be submerged with the submarine, hard bronze sleeve bearings were used throughout, instead of traditional roller bearings. As part of the project, dozens of bronze sleeve bearings had to be cleaned by a sanding/honing process and in some cases small amounts of material removed to allow smooth operation.

After hours of laborious and time-consuming hand scraping and sanding processes to restore the bearings,  Pekelney’s method of expanding spring-loaded hones were minimally effective, wore out quickly and did not keep the sleeve bearings absolutely round.

In search of a better solution, he sought the advice of Charlie Butcher, a 40-year master diesel mechanic. “[Butcher] pulled out a Flex-Hone and told me not to fool with anything else,” says Pekelney. 

The Flex-Hone tool, manufactured by Los Angeles-based Brush Research Manufacturing, is characterized by the small, abrasive globules that are permanently mounted to flexible filaments. It is available in many sizes, abrasive types and grits and is automatically self-centering and can be used with any standard electric drill. Parts such as bushings, bore sleeves, hydraulic and pneumatic cylinders, and other cylindrical cavities can be surface finished in the field using a relatively inexpensive item.

FFJ 07816 gun image3

The Flex-Hone tool has small, abrasive globules that are permanently mounted to flexible filaments.

Preservation

“The Flex-Hone [gives] good control over how much material is removed, and the holes remain concentric,” says Pekelney, adding that for the museum environment it was important they preserve as much original material as possible. “I was able to clean up these bearings pretty quickly. The hones have saved a huge amount of time compared to hand scraping.”

Pekelney’s inexperience with the flexible hone proved to be a non-issue. “The tool enabled me, an inexperienced machinist, to repair bearings with very little risk of damage that otherwise would have required journeyman help,” says Pekelney, who is already planning future uses for the tool.

“I wish I had known about the ball hones when I was working on the submarine’s Bofors 40mm guns,” he adds. “I spent hours working on one particular bushing that probably would have taken minutes with the Flex-Hone.” FFJ

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