Thursday, December 11, 2014

Rock Ridge Flour Mill

To recap the idea behind the Rock Ridge series, not everyone is going to be able to go back to living off of the land after a major catastrophe. There will be those who are not suited to raising their own food, but will have other skills that they can use to make a living. I am using the fictional town of Rock Ridge (ca. 1870) as an example of the skills and services that may be in demand after TSHTF. It doesn't have to be “Mad Max in Thunderdome”; people lived comfortably in small towns and villages for centuries before the invention of electric lighting and automobiles.

First things first: any time you see the word “mill”, you're looking at a facility that takes in a raw material and produces a marketable product, with windmills being the sole exception that proves the rule. Wood (or saw) mills take in logs and put out lumber; cotton mills take raw cotton and turn it into thread; a grain mill will take grain and turn it into flour or meal suitable for use as a cooking ingredient.

If you have a reliable source of energy and grain, you might be able to make a living with a grain mill. Grain mills are simply large versions of the basic stone utensils that have been used to make flour out of grain for as long as humans have been growing grain.

Historical Mills
Credit: My photo
The most basic grain mill is a bowl-shaped stone (called a “mortar”) and a smaller rounded stone that fits inside the bowl (known as a “pestle”). Grain is placed in the mortar and the pestle is either rolled over it with downward pressure or pounded down on the grain to break it up into tiny pieces. Roughly ground grain is called meal, and finely ground grain is called flour.
Credit: My photo

Hand mills have evolved into steel and plastic kitchen appliances that vary in quality and price. The general rule that “you get what you pay for” holds true for hand mills, so get the best that you can afford. Unless you have a bullet-proof source of electricity, avoid motorized mills that don't also have a manual method of operation.
Grinders like this have been used for decades to mix and grind meats, but if you get the right plates for it you can grind grain. Avoid the cheap ones since they are generally of very poor fit and finish.

While a single person can grind enough grain into flour to keep their family in bread, it is time consuming and not a very efficient use of time. A centralized grain mill will tap into a local source of power and provide the service of producing flour (or meal) for its customers in return for a percentage of the grain. The miller's percentage would be sold or traded to people who didn't grow grain, and provided a source of income for the miller.

Credit: My photo
A small commercial mill, like those found in villages, was usually made of two discs of stone (often pieces of stone held inside a metal ring). They were placed face to face and the grain was introduced through the center hole of the top stone. The grain was turned into flour as it worked its way out toward the the rim.

Power would be provided by a horse, mule, or ox yoked to the top stone. Grain straight from the field was often placed on the ground in the animal's path and their hooves would strip the husks (chaff) from the grain as they walked on it. (I will go through the process of harvesting and processing grains in a future post, in order to keep this one on topic and of readable length.)

Credit: Public Domain
A moderately-sized mill, suitable for a small town, would consist of two round stones, one placed flat and the other on edge riding on the top of it. Grain would be added to the top of the base stone as the wheel stone rolls around on top of it and the grain ground between the two.

Power sources for this size of mill would be a water wheel set on a stream or a wind mill with large sails. High torque, low speed power that can be harnessed with the use of mainly wooden gears and shafts is a good fit for this kind of mill.

A large mill, producing flour for a large bakery or a large town, would likely consist of a series of smaller mills in series, with them set to grind the grain into progressively smaller pieces. Larger mills are/were powered by steam engines, electric motors, or some form of internal combustion engine.

Modern Mills
Modern mills use metal rollers or shears, usually made of stainless steel, to grind grain into flour. Steel rollers have some advantages over stone:
  • Stone grinding wears down the grinders slowly, leaving sand or grit in the flour. This is not normally hazardous to the health of the consumers, but it can lead to increased wear on their teeth. Steel rollers last a lot longer and are easier to replace with modern infrastructure. 
  • Since steel wears slower than stone, it is easier to set and maintain the desired degree of grind you want. 
  • Steel is less porous than stone, so it is easier to keep clean and prevent contamination of new flour from spoiled remnants of previous grindings. 
  • Steel rollers can be run at higher speeds than stone mills, increasing the output for a given size of mill.
  • Steel rollers generally weigh less than stone ones, so starting and stopping the machinery is easier.

Stone rollers also have a few advantages:
  • They can be made of locally available materials. 
  • Stone rollers are not as likely to create sparks as metal ones. Dust explosions are a major hazard of any grain handling operation, so sparks are to be avoided as much as possible . 
  • The weight of stone rollers provides enough pressure without requiring tensioners
  • Running at a slower speed allows for the use of simpler bearings and shafts, often made of wood instead of metal. Lower speeds also mean less heat, which can damage the grain or contribute to dust explosions. 
  • The mass of stone rollers provides inertia to the operation which will smooth out minor variations in the power source. This is helpful when using wind or some other form of variable power. 

Becoming  a Miller
Setting up a grain mill is a time-consuming process that will require a source of power, a good supply of materials, a source of grain, storage for grain and flour, and a customer base. Operating it will require a low level of daily supervision, a moderate amount of maintenance, and plenty of customer interaction.

A good miller will work with his customers as much as his machinery, and his reputation can make or break his business. Bookkeeping and an accurate set of scales will help keep both the customers and the miller honest, so plan for them as well. 

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