Mill building, 1961
LM&E: Milling Overview
Corn Meal
Although the mill was built to produce 70 barrels (1bbl weighed 196 lbs or 14 British stones) of flour a day, corn meal was also produced in a smaller amount. Corn was dumped into a hopper on the first floor and it emptied into a corn crusher in the basement. The corn crusher broke the kernels into smaller pieces that emptied into the foot of an elevator. It carried the crushed corn back up to the first floor where it emptied into a three roll -2 break roller mill. The top and middle roller would break the corn into coarse pieces, then be ground into finer pieces by the middle and lower rollers to produce cornmeal.
Flour
The process of converting a bucket of wheat to a sack of flour involves a number of steps, and there is a machine for each step. Since materials were fed into the tops of the machines and came out at the bottom, there had to be a way to get the materials from the bottom of one machine to the top of the next machine in the process. The usual way to do that was to have a mill building with three (or four) floors with the roller mills, the heaviest machines, on the first floor. Elevators would move grain from the roller mills to the second and third floors where other machines would clean and sift the material. Chutes from each machine directed the material down to the next machine in the process or to an elevator that would bring the material up to the next machine.
Mill Infrastructure
Power: At the Lewisburg Milling & Electric Company, the machines were powered by an 80 HP steam engine with steam produced by a coal-fired boiler with a 50' brick chimney. The chimney was located in the vicinity of the stairs that come down by the driveway and the boiler was behind the log building. The boiler would have burned around a ton of coal a day and water for the boiler would have come from the Andrew Lewis spring across the street.
A large belt went from the steam engine near the corner of the Clingman Center porch, through an opening in the foundation wall near where the door under the deck is now located, and around a pulley on the basement line shaft. The size of a pulley was determined by the speed of the line shaft and the speed required by the machines. For instance, the roller mill rpm was much higher than the line shaft while the elevators ran at a much lower rpm. The roller mills were located directly above the basement line shaft and required far more power than the machines on the upper floors. Power for line shafts on the upper floors was transmitted by a vertical shaft connected to line shafts on each floor with bevel gears.
Line shaft: Steel shafts hung from brackets on the underside of each floor of the mill building. Each shaft would have a number of pulleys of different sizes with leather or fabric belts connecting the line shaft to the pulley of the machine being driven. The diameters of the machine and shaft pulleys were selected to match the optimum speed for the machine to the the line shaft speed. There would also be a lever or other mechanism to disengage the belt from the line shaft. The line shaft in the basement operated at a higher speed since the roller mills on the first floor ran at relatively high speed, around 500 RPM. The machines on the second and third floors ran at low speeds so the line shafts turned much slower than the basement shaft.
Elevator: A device that moves material up from one floor to the next and consists of several components: a) A series of cups is attached to a belt, often made of cloth. b) The belt with cups runs over a pulley in the elevator head which is powered by the line shaft and pulls the belt and cups up. When a cup goes over the top of the pulley, the grain is thrown out to a chute which goes down into a bin or machine. c) The elevator foot is at the lower end of the elevator. It consists of a box with a shaft and pulley for the belt. Grain is poured into the box and as the belt goes around the pulley, the cup scoops up grain and carries it up to the head. d) Trunks connect the foot and head and are each made from 4 long boards forming a square tube to keep the grain clean as it is moved from one machine to the next. Mills similar to LM&E often had a dozen elevators to move grain between machines during the milling process.
Milling Overview
There are six basic steps to convert the kernels of wheat into white flour: Cleaning and screening to remove impurities; breaking the cleaned grain into coarse pieces that contain the bran, germ, and endosperm; purification separates the lighter bran from the heavier middlings (endosperm pieces); reduction - the middlings are run through a series of smooth rollers to grind the endosperm into finer particles and separate it from the bran particles , bolting or sifting the flour to the desired fineness with coarser particles going back for further reduction; and packaging the flour into 196 lb barrels, 98 lb cloth sacks, or smaller sacks.
This is an overview of the sequence of steps and machines that converted wheat into white flour:
wheat kernels → separator → scourer → break #1 → bran duster → break #2 → purifier → reduction rollers 1,2,3 → Salem sifters → rollers 4,5,6 → reels → packaging