Farm blacksmithing

This book is the direct outgrowth of the author's experiences in teaching farm blacksmithing to farm boys. The objects, of which the process of making is described in the book, all  center about farm activities.
The purpose of the book is two-fold. It is intended as an  aid to a teacher of farm blacksmithing, being a source of problems, and suggestive of how the work may be carried forward.

In addition to being a "What" and "How" book for instructors,  the author constantly had in mind its direct use by farmers as a  means of self-instruction in blacksmithing. This accounts for  certain details and some repetitions. Because of its intended use  as a book of self -instruction the author has taken little for granted.

Farm blacksmithing is a rougher type of work than that  expected of a city smith on automobile or auto truck work.  The important question is: "Does it fit and is it strong enough?"  In welding the question is not, "How does it look?" but "Will  it hold?"

The dimensions given on the drawings in this book are such  that the work will be strong enough and of a size in general use.  The sizes should, however, be modified when individual needs  require. There is real value in making these new objects to  dimensions, because only in that way will a person learn how  to make duplicate parts for repairs.

Repair work in schools is only touched on briefly in this book.  It should be stressed as much as possible, the students bringing  broken parts of implements, etc., to school to repair. However,  one who has forged most of the articles, as shown in this book,  should be able to do almost any kind of blacksmith repair work  on a farm.

Hardening is making the tool steel as hard as possible, and tempering is reducing the hardness to a certain definite desired degree.

Hardening Heat the tool steel to a blood red heat and plunge into clean, cool water. The addition of salt in the water has a tendency to make the hardness greater. The water should be kept cool by changing or adding, when numerous articles are hardened. The steel is now as hard as it can be made, and it cannot be filed.

Tempering After a piece of tool steel has been hardened, a certain definite degree of hardness may be obtained by reheating it to a given temperature. The temperature is determined by the color on a polished surface of the tool. The use for which a tool is intended determines the degree to which it is to be tempered, and therefore the color to which it is to be heated.

The first color to appear on the polished surface, when reheating for tempering, is light straw. At this color the steel is tempered just a trifle. After light straw the colors appear in the following order: dark straw, brown, purple, dark blue and light blue. A light blue color indicates that the steel has been tempered to the softest point before it returns to its original condition.

Many tools can be hardened and tempered in one heating. The cold chisel, Plate 27, is such a tool.

Hardening and Tempering the Cold Chisel First heat about 2 inches or 2 1/2 inches of the cutting end to a blood red heat, using a slow fire with little draft. Plunge the point into cool water to a depth of about 1 inch. Move backward and forward, and up and down slightly. This movement prevents the steel from hardening to a definite water line. Such hardening to a water line usually results in a break when the chisel is struck. When the 1 inch or so of the point has been thoroly cooled, remove from the water and quickly polish with a piece of emery cloth, tacked on a stick. The heat remaining in the upper part of the chisel will now begin to run down into the cooled and hardened end, and the tempering will have begun. The colors will now appear. The first color to be noted on the cutting edge will be light straw. Above this will be dark straw brown, purple, dark blue and light blue. The colors move down as the heat from above runs down. The light straw will disappear on the edge and the dark straw above it will take its place. Then the dark straw will disappear, and so on until the dark blue color reaches the cutting edge. The moment the edge is dark blue plunge into cool water.

For general use a dark blue is the proper color to temper a cold chisel. A hard test is to hammer it straight into a piece of iron. If the edge does not bend or crack the tool will give good service. The center punch, Plate 27, is hardened and tempered in the same manner.

Tools and Their Tempering Colors The farm blacksmith has little call for tempering to any of the harder colors. Light and dark straw and brown are used principally on machinist's tools and fine instruments.

Brown Used for ball pein and other heavy hammers.

Purple Used on center punches, stone drills, occasionally on cold chisels, and the faces of riveting hammers.

Dark blue Used on cold chisels, lever or wrecking bars, some knives, blacksmith's cold chisels or cutters, hardies when used for cutting cold stock, and the pein of a riveting hammer.

Light blue Used on screwdrivers.

Tools used for cutting or shaping hot stock, such as punches, hot chisels and hardies, do not require hardening and tempering.

Annealing Sometimes it is desirable or necessary to bring the steel back to its original condition. This is a softening process and is sometimes used after a tool has been forged, and before it is hardened and tempered. One way to anneal is to heat the iron to a good red heat and bury it in dry lime or ashes and allow it to cool. A decidedly quicker method is to heat to a good red color and allow it to cool in the air until no heat color is visible when held in a dark corner of room. When this point is reached cool entirely by plunging into water. Annealing is done to eliminate any strains in the steel such as might be caused by hammering, bending or hardening.

Case Hardening Case hardening is a process of hardening the surface of wrought iron or mild steel, which cannot be hardened and tempered . like tool steel. Where no special furnace and equipment is available the method described under Ice Tongs may be used. Case hardening simply hardens a thin layer of the outside surface. By repeating the process several times the thickness of the hardened part may be materially increased.

Pay especial attention to the "Notes," Page 78, cautioning against poisoning from the cyanide of potassium and its fumes.

It is a good plan for the fanner to save such bolts, nuts, rods, sheet iron, etc., which may come to hand in one way of another. Such things can sometimes be used as they are, or can easily be changed to a size or shape needed. A small supply of various sizes of screws, nails, bolts of various kinds, pipe, rivets and iron rods should be kept in the farm shop so that repairs and new work can proceed without the farmer first having to go to town for materials.