Part II – The Giant Lathe
To turn the large stone blanks from the granite by the sea into columns required a lathe of unheard of size, because each of the 310 ton raw stone blanks needed to be sculpted to 54 feet high and 6 feet in diameter. As a result the final column would weigh 160 tons. The church commissioned the design and construction of the lathe. It was designed and patented by E. R. Cheney and H. A. Spiller of Boston. It was built by the Philadelphia Roll and Machine Company of Philadelphia. Its construction was begun in December, 1899, and it was delivered at the quarry in May, 1900. It was erected at Vinalhaven under the supervision of J. W. Bourn, the foreman of the machine shop.
The lathe is 86 feet long and weighs 135 tons. It has a capacity to work a stone 60 feet long and a maximum diameter of 6 feet 6 inches. Eight cutting tools are used, each capable of taking up to a 3 inch cut so that the column can be reduced 2 feet each time the cutters traverse the entire length of the bed. In practice the cut was usually set at 1.5 inches. The result is a splintering or spalling of the face of the stone.
Dressing and Polishing the Column
When the column is dressed to shape, cup shaped devices are attached to the tool posts and filled with hardened steel shot. This gives the surface a rough polishing. Likewise, the final high polishing is done the same way using sand and powdered emery. The granite columns make 1.75 revolutions per minute during the operation of turning. During the polishing operation the column makes about 3 revolutions per minute. The countershaft to which the lathe is belted is driven by a steam engine of 50 HP. Finally each 300 ton blank will be reduced to 130 tons and take 6 weeks to complete.
The scientific, architectural, engineering and manufacturing communities followed this mammoth undertaking for months. Therefore the design, quarrying, turning and polishing of the granite by the sea and the lathe captured the attention and imagination of a large portion of the country.
The First Granite Stone Broke in the Lathe
It was found impossible to turn the columns in single blocks. The first three put into the lathe broke under their own weight after considerable work had been expended on them. The ends of the granite columns were held in large chucks or faceplates. Therefore the entire weight of the column was carried by these two faceplates, almost 60 feet apart. As a result therein was the problem as the first stone broke in the middle.
The designer of the lathe said that the proportions were to blame and that the design length would need to have a diameter of eight feet in order to sustain its own weight. It was also indicated that some areas of the quarry had a seam running through it which made it necessary to cut some stone across the grain. Various attempts were made to reduce the bending stress in the middle without success.
Also, numerous other plans were suggested by ingenious inventors to get the granite by the sea on a lathe. One of the most promising was to set the column on end on the center of a revolving table and turn it by tools traveling on a fixed vertical bed. While this plan may have been all right mechanically, the cost of a 75 foot stable tower to support the stone from deflection and carry the turning tools was not practical. The mere setting on end a block of stone weighing some 300 tons was a task not to be taken lightly.
“No Monolithic Columns for the New Cathedral”
In the end, the quarry insisted that monolithic columns would not be possible and the Board of Trustees had no alternative but to accept the new dimensions of a two part column. The lower piece would be thirty-eight feet long and weigh 90 tons. In contrast the upper piece would be 17 feet long and weigh 40 tons. The diameter of the columns would remain at 6 feet.
The ocean tug, Clara Clarita towed the specially built barge, Benjamin Franklin to deliver the columns to New York. Two columns were loaded for each voyage of eight days duration. The destination was 134th Street Pier, Hudson River. Built in 1864 as a luxury steam yacht, then converted to an ocean tug, it was owned by Boston Towing Company at the time of the moving of the columns. Finally the first load arrived July 10, 1903.
- Scientific American, January 12, 1901
- Engineering News, December 3, 1903
- Machinery Magazine, April, 1901