The Manhattan project: a contractor, patternmaker and metalcasting facility collaborated on 43,000 castings to produce a replica of the original fence surrounding New York City's Central Park Jacqueline Kennedy Onassis Reservoir.

Every day, thousands of New York joggers pound the path surrounding the Central Park Jacqueline Kennedy Onassis Reservoir, which is circled by a newly-installed ornamental fence set against the backdrop of the Manhattan skyline. Many will take note of the grace of the casting details along the fence, but few will realize the complicated engineering work that went into manufacturing the unique castings.

From 1862 until 1926, an ornamental cast iron fence surrounded the Central Park Reservoir. But in 1926, a chain-link fence replaced the original, and over time, the decorative posts were all but forgotten. Seventy years later, scuba divers cleaning the reservoir found a section of the original fence, and its appearance sparked the imagination and generosity of a New York couple, who contacted the Central Park Conservancy and pledged to provide funding for a new fence. Soon after, the conservancy launched a project to replace the mundane chain-link fence with a replica of the original ornamental fence.

Almost immediately, there were those who doubted a replica true to the original could be fashioned. The original fence's design consisted of finials and ornamental unions that were cast around, rather than fastened to, its pickets and rails. The only mechanical fasteners visible were used to join the panels to the posts. The same would have to be true of the replica--no pins, fasteners or welds could be visible. The fence would run 8,150 ft. (2,484 m) around the reservoir, stand 48 in. (122 cm) high, and consist of 1,535 fence panels and 1,538 posts. It was a tall order for Welding Works, Madison, Conn., the firm that was awarded the contract, and it was a tall order for the metalcasting facilities hired to produce the fence components.

In six months time, the fence was completed true to the original and its cast-on embellishments. But it was not without the group effort of a contractor, patternmaker and metalcasting facility that a solution to the casting dilemma could be found.

The Assignment

When Welding Works first was asked to bid on the project, it knew the casting aspect of the fence would prove challenging. The firm searched for metalcasting facilities all over New England as well as in Ohio and Pennsylvania to supply a quote on the project. However, only two metalcasters responded, and Cumberland Foundry, Cumberland, R.I., was contracted for the project. With an estimate on the casting cost in hand, Welding Works turned in its own bid to the Central Park Conservancy for the project.

When Welding Works won the fence contract, Walter Camp, vice president of the company, knew it was imperative to find a way to make the casting work.

"When the fence project was first out to bid, we looked at the job and the specifications, and we knew there would be complications," Camp said. "When we got the job, we knew the casting was a critical part, and we didn't have the details worked out yet."

Meanwhile, the pressure was on Cumberland Foundry.

"It was one of those things where we put in a bid not thinking we would actually get the project," said Al Lucchetti, president of Cumberland Foundry.

With a time constraint that left little breathing room, all focus was given to successfully completing the cast-arounds. The panels of the fence would consist of steel rods welded together, and a manufacturing method had to be developed to cast around the weldment in a cost-effective, productive manner. Every vertical and horizontal joint had to be cast-on. The fence also had to comply with new, stricter engineering codes that the original fence did not have to meet. This meant devising a mold that would fit snugly enough at each union for exact castings and determining a way to introduce the steel rods into the mold for a precise fit for each of the 1,535 fence panels. Each panel was 66 in. (167 cm) long and required 26 castings. The panels would be connected by fence posts (1,538 total), which required two castings each. All told, the entire project would encompass more than 43,000 castings.

The Solution

Central Park Conservancy supplied a plastic mold fashioned out of a section of the original fence to use as a model for the replica. Because of the tight schedule (the fence was expected to be completed within six months), Welding Works was heavily involved in the patternmaking and mold-designing process. The firm hired Case Patterns and Wood Products, Groton, Conn., to help in designing the pattern for the mold. Originally, the casting facility intended to use green sand molds, but it was soon determined it would be too labor-intensive for this project.

"We sat down with our patternmaker, Jim (Case), and brainstormed to find a way to make the mold," Camp said. "Finally, the decision to use a cast-iron three-piece (permanent) mold was made."

The challenge here was to ensure sufficient iron entered the mold and filled all the gaps while allowing removal of the casting without it becoming damaged. The solution was a permanent mold fashioned as a book mold. The fence panel would be set horizontally into the lower half of the mold, and the other half of the mold would close over it on top, like a book. Additionally, two loose mold pieces would be set in the lower half of the mold. These would accommodate for the radius of the steel rods of the fence panel and allow the molten iron to follow the contours of the panel.

Originally, the plan was to use four mold assemblies, but eventually 19 assemblies using more than 1,400 molds were made in order to speed up production.

With so many fence panels to be cast-on, a productive way of pouring also had to be devised to keep the fence panels affixed at the correct positions. Cumberland fashioned a clamping system that clamped in the fence panels as they were set in place in the permanent molds. Molten iron was then poured around the steel rods. Cumberland made eight of these clamping apparatuses, so the facility could pour eight panels of 26 castings at one time.

Sand cores were placed on top of the molds, and molten iron was gravity-poured through the cores in order to facilitate proper pouring and accommodate shrinkage during solidification.

To ease production pressure, another metalcasting facility, G&W Foundry, Rehboth. Mass., contributed in casting the finials (which were cast in similar fashion to the panels) on a portion of the fence posts. Welding Works completed all the machining and grinding of the cast-on elements.

The Result

Forty-three thousand castings and 1.5 mi. (2.5 km) of fence panels later, the replica was dedicated in December 2003. The new fence, which recalls the grace and style of the original, has been met with overwhelming approval. The Manhattan skyline and view of the reservoir is no longer marred by a tall chain-link fence. Instead, it is accented by a fence befitting one of the most famous parks in the world.

"The fence has been very well received. It restores the historic aesthetic of the reservoir and changes people's entire perception of Central Park," said Christopher Nolan, the Central Park C0nservancy's vice president for capital improvements.

The project also warranted the "Fence Project of the Year Award," which was presented by the American Fence Assn. in 2004.

"The end product was wonderful," Camp said. "It was an incredible project."