The building of the gristmill involved the installation of all of the equipment needed for the grinding of grains. First and foremost were the two sets of buhrstones that were put in place soon after the gristmill was built in 1854. Each set of buhrstones is comprised of two stones, bound by iron bands to support it and keep it from cracking or crumbling. Each stone weighs one ton.
The bottom buhrstone is mounted in a platform and is motionless. An axle, which propels a drive bar, protrudes through the middle of this bottom stone. Before conversion to electricity the steam engine in the basement provided the power. The top stone rests above the bottom stone and spins when in operation; the drive bar propels this stone. These buhrstones grind at their best quality when they are 1/100 of an inch apart. To achieve such precision, the cutting edge of the stones must be level and stones must be balanced. Covers encase the stones so that, when the flour is ground, it is caught and guided into a chute. Of interest in the grinding process is a unique alarm system that is still in use and that warns the miller when not enough grain is reaching the buhrstones. The sound of this alarm bell strikes fear in the miller because sparks from the flint of the stones could touch off an explosion, if allowed to grind away at each other.
In grinding with buhrstones, the wheat flows into the eye (i.e., center) of the top stone, which leads to the grinding surface between the two stones. The wheat is then guided through furrows to the outside of the stones. The circular motion of the top stone pulls the wheat out of the furrows on to the raised potion of the grinding surface, where it actually cut and not crushed. The buhrstones are flint, a very hard rock that will wear very little. Nevertheless, the stones need to be sharpened occasionally; this sharpening consists of cutting the furrows. The furrows in the Saint Vincent buhrstones are cut with a style which resembles swirls emanating from the center of the stone. The process of sharpening involves chipping away with a special pick to cut the furrows. So arduous is the task, it takes about nine eight-hour work days to sharpen one stone.
Once these two sets of buhrstones had been placed in operation in 1854, Wimmer soon judged that they would not be able to handle the demands of the institution. And so he ordered an additional set from the same French quarry. At the same time Wimmer purchased a machine to grind and crush corn. It was also in 1854 that the eighteen-foot sifting bolt was built and installed on the gristmill’s third floor, where it has been in continuous operation down to the present. This machine takes the whole wheat flour as ground by the stones, and sifts it into its component parts of unbleached flour, middlings, and bran. An ingeniously crafted bucket-and-belt elevator takes the flour from the stone, as it falls into the basement, up to the third floor and into this sifting bolt. The sifting mechanism of this bolt is a six-sided revolving cylindrical wooden frame covered by silk of different weave densities. The whole wheat flour flows through the inside of this tube. As it spins, the unbleached flour, which is the finest part of the whole wheat flour, is sifted through the 10XX and 12XX silk. The middlings would be sifted through the 0XX and 2XX silk. The bran is not even sifted; it is expelled through the end of the tube. The trough of the bolt, where the flour falls, cradles an auger which directs the flour and middlings to their particular chutes that lead to the first floor. As an aside, it is interesting to note that gristmills are traditionally built in such a manner that most operating and collecting can be done on the same floor—usually the first or ground floor.
Efficient as the sifting bolt was, some of the unbleached flour was not ground powdery enough to be sifted through the fine silk screen and was intermingled with the middlings. Thus, in 1885, Saint Vincent purchased a George T. Smith Middlings Purifier for $225 to improve the yield of the unbleached flour. This Purifier, built in Chautauqua County, New York, is made almost entirely from ash wood, a very hard wood used to endure many years of wear—and is in use even now. The machine resifts the middlings using a similar silk screen and brushed to assist the sifting process. This process separates the coarse unbleached flour from the true middlings and then send the flour to a smaller set of buhrstones to be reground into a finer powder-like flour. This smaller set of fourteen inch buhrstones had been purchased in 1883 for $140. Through this process the increase in the yield of unbleached flour is approximately twenty percent. Now, when sifted, the ground whole wheat flour yielded the following quantity of products by weight: sixty percent unbleached flour, twenty percent middlings, and twenty percent bran. This increase in the yield of unbleached flour is very significant, since it was in the greatest demand, especially for the baking of bread The middlings and the bran were used occasionally for cereal, but were chiefly used to feed animals.
In July 1908, two Howe grain cleaners were purchased for the use of the gristmill and the Saint Vincent farm. The first was a wheat cleaner that was used exclusively by the gristmill to separate chaff and other impurities from the wheat before it was ground into flour. It also beat the wheat in a scourer in order to remove must. Must is a type of mold or mildew that is caused by improper drying of the wheat. After this cleaning process the wheat is passed through a box containing a series of magnets in order to catch any minute metal particles which might have slipped through during the grain cleaning and screening processes. The reasoning is that metal, even the smallest shaving, is dangerous near grinding stones. The second cleaner was a larger one that could be used with any type of grain by changing the separating trays. This second cleaner scoured all of the grain to be used as seed the following year, so that the farmers would not plant weed-seeds like grass, cockle, or thistle along with the crop. Three other additions to the gristmill are the following: a hammer mill was purchased in 1948 to grind cornmeal for the monks and feed for the chickens. It did not last very long; in 1965 a new one was purchased. The second addition was a new bolting cloth for the sifting bolt, after the original had been in use for 97 yeas. This cloth was installed in May 1951; was made entirely of silk; and had four different sifting densities. But in August 1990 it was replaced with a polyurethane and nylon one. A third addition, made in 1954, was a set of small buhrstones to replace the one acquired in 1883. These new sixteen-inch stones, purchased secondhand for $50, were set on a horizontal axis, unlike the previous stones that were on a vertical axis.