Setting Out

As master builder, James Bambridge’s job is to plan and direct the overall project. He coordinates the production of working drawings from the architect’s plans with the delivery of stone from the quarry. He has to follow the stone’s progress through the yard and its final application to the southwest tower. Ordinarily, a specialist working under Bambridge would do the setting out. They would turn out half-inch scale working drawings from the architect’s one-eighth scale renderings. They would also produce the full scale templates in zinc. These cross sections of complicated stone units, such as colonetted columns, are laid out on a spacious floor. It would be similar to a full-scale lofting floor in a boatyard. Bambridge had space in the cathedral’s crypt for doing this.

The interior was largely complete by the time construction ceased in 1941. The exterior, where the absence of any towers created a harsh, cut-off look was much more obviously unfinished. The original architectural firm of Ralph Adams Cram became Hoyle Doran and Berry Architects in the 1940’s. Cram left drawings for the front two towers, as well as for a still larger Central tower over the cathedral’s crossing. The latest revisions to the cathedral drawings were done by Cram before his death in 1942. It is these drawings that provide the basic outline for the work facing Bambridge and his crew. John Doran of the successor firm was one of only a few architects at the time that construction on the cathedral restarted in the 1980’s that could draw gothic structures.

Starting Where the Architect Left Off

The process is complex, however, since the designs Cram left were never detailed or made into working drawings. Since the size, shape and placement of each stone must be determined in advance, Mr. Bambridge’s role in design was as crucial as the architect’s. While initial preparations were underway in the stoneyard, Bambridge worked on the drawings from his home in Cornwall and in New York. He had an office in Diocesan House and an apartment in Synod House, both in the Cathedral Close.

The working drawing shows every stone in the face. In the center of each is a circled number. Each stone has its own number and each has a card in Bambridge’s file describing it and its position, in code. S would mean the south tower. D means it’s the fourth section up. The fraction numbers are its dimensions. The other number is its cubic volume. At year’s end, Bambridge totes up how much foot cubage is produced. He checks it against the foot-cubage the quarry has delivered and arrives at a waste factor. That factor is important in cost control. His nerve center is a room in the cathedral’s basement. Crouched on the floor, he turned the drawings into programs for stone cutting.

The Setting Out Uses Zinc Templates

Zinc is used in making the templates as it does not contract or expand based on the temperature in the stone cutting shed. It was necessary to create full size drawings of some sections in order to make the trade work templates. This was done by first sliding a sheet of zinc under the full size drawing. Holes were then pricked through the paper at relevant points onto the zinc below along the lines of the drawing creating a series of dots. The dots were then connected to form the lines of the template. The lines were created with a sharp scriber forming a thin groove on the surface of the zinc. The surface was then treated with a copper sulfate solution which reacted with the zinc to make black clear lines. The zinc was then snapped by repeating the scribing process or cut with tin snips.

In addition to cutting the template, the specialist would specify joints for the stonecutters, produce a job ticket on each stone to be cut and take care of production schedules. Since only Bambridge was in on the original planning and timetable decisions, he did both planning and directing. Bambridge later taught D’Ellis Kincannon this part of the process and turned it over to him. He became highly accomplished at the setting out process. Cynie Linton also learned to do the setting out. Over time, mylar replaced the traditional zinc which made an easier and less expensive process.

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From Cutting Shed to Tower

Each card in Bambridge’s file becomes a job ticket that goes to the stoneyard. When a stone is produced from it, the master mason takes a crayon pencil and colors that numbered stone on his copy of the working drawing. This system means that no stone is duplicated. The stones are cut to millimeter accuracy, just like medieval stonework. The towers could be put up dry. Mortar is used to take up minute discrepancies in the stone, and to keep out the weather.

The yardstick used is to design and cut so that it would stay up there on its own with no mortar.

– James Bambridge

In a modern masonry building, once the second floor is designed, the same pattern repeats for the next 20 floors. Here, each stone is an individual piece to fit a given space. In the 12th century they would work the stone as it came from the quarry. The stone was cut to whatever it would make. To keep faith with that medieval system, Bambridge would deliberately throw in an off-length ashlar or quoin. Therefore when someone looks up at the building it would not look totally repetitive all the way up. The eye is forced to move around. This then replicates more of the old Gothic style.

Dean Morton liked to point out that the use of such 700-year-old techniques is what separates the work at St. John from other contemporary cathedral building projects, such as the National Cathedral in Washington, D.C. “Their ashlars are all cut and finished to standard sizes at the quarry. They’re delivered to the site ready to lay up like bricks.”

Thanks to Steve Boyle for all he contributed to this post