Blacksmith
From Wikipedia, the free encyclopedia
A blacksmith is a person who creates objects from iron or steel by "forging" the metal; i.e., by using hand tools to hammer, bend, cut and otherwise shape it in its non-liquid form. Usually the metal is heated until it glows red or orange as part of the forging process. Blacksmiths create such products as wrought iron gates, grills, railings, light fixtures, furniture, sculpture, tools, decorative and religious items, cooking utensils and weapons. A skilled blacksmith can, with minimal effort, make a sophisticated product that looks good and demonstrates ingenuity.
A blacksmith who works primarily with horses, especially making and fitting horse shoes, is called a farrier.
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[edit] The process of blacksmithing
Blacksmiths work with "black" metals, especially iron. The black color comes from a layer of oxides that form on the surface of the metal during heating (called fire scale).
The term "smith" originates from the word "smite", which means to hit. Thus, a blacksmith is a person who smites the black metals.
Blacksmiths work by heating pieces of wrought iron or steel in a forge until the metal becomes soft enough to be shaped with tools such as a hammer. Heating is accomplished by the use of a forge fueled by propane, natural gas, coal, charcoal, or coke.
Modern blacksmiths may also employ an oxyacetylene or similar blowtorch for more localized heating. Color is important for indicating the temperature and workability of the metal: As iron is heated to increasing temperatures, it first glows red, then orange, yellow and finally white. The ideal heat for most forging is the yellow-orange color appropriately known as a "forging heat." Because they must be able to see the glowing color of the metal, many blacksmiths work in dim, low-light conditions.
The techniques of blacksmithing may be roughly divided into forging (sometimes called "sculpting"), welding, heat treating and finishing.
[edit] Forging
Forging is also referred to as sculpting because it is the process of shaping metal. Forging is different from machining in that material is not removed by these processes (with the exception of punching and cutting), rather the iron is hammered into shape.
There are five basic operations or techniques employed in forging: drawing, shrinking, bending, upsetting and punching.
These operations generally employ hammer and anvil at a minimum, but smiths will also make use of other tools and techniques to accommodate odd sized or repetitive jobs.
[edit] Drawing
- Drawing lengthens the metal by reducing one or both of the other two dimensions. As the depth is reduced, the width narrowed, or both the piece is lengthened or "drawn out".
- As an example of drawing, a smith making a wood chisel might flatten a square bar of steel, lengthening the metal, reducing its depth but keeping its width consistent.
- Drawing does not have to be uniform. A taper can result as in making a wedge or the woodworking chisel blade. If tapered in two dimensions a point results.
- Drawing can be accomplished with a variety of tools and methods. Two typical methods using only hammer and anvil would be: hammering on the anvil horn, and hammering on the anvil face using the cross peen of a hammer.
- Another method for drawing is to use a tool called a fuller, or the peen of the hammer to hasten the drawing out of a thick piece of metal. The technique is called fullering from the tool. Fullering consists of hammering a series of indentations (with corresponding ridges) perpendicular to the long section of the piece being drawn. The resulting effect will be to look somewhat like waves along the top of the piece. Then the hammer is turned over to use the flat face and the tops of the ridges are hammered down level with the bottoms of the indentations. This forces the metal to grow in length (and width if left unchecked) much faster than just hammering with the flat face of the hammer.
[edit] Upsetting
- Upsetting is the process of thickening the metal by reducing one dimension and increasing the other two. It can be described as pushing the metal back into itself to thicken it. For example in preparation for making a bolt head, a smith will hammer the end of a rod, thickening the end of the rod and shortening its overall length. The heated end of the rod is placed pointing down on an anvil. The cool end is then struck repeatedly, which produces a bulge at the hot end of the metal.
[edit] Shrinking
- Shrinking, while similar to upsetting, is essentially the opposite process as drawing. As the edge of a flat piece is curved such as in the making of a bowl shape, the edge will become wavy as the material bunches up in a shorter radius. At this point the wavy portion is heated and the waves are gently pounded flat to conform to the desired shape. If you were to compare the edge of the new shape to the original piece, you would discover that the material is thicker than before. This is due to the excess material that formed the waves being pushed into a uniform edge that has a smaller radius than before.
[edit] Bending
- Bending at its simplest is simply that: bending the metal to a particular shape. Hooks are made this way, as well as loops and chain links from rod.
- Bending can be done with the hammer and anvil although blacksmiths tend to make jigs and specialized tools to make the process easier and more consistent. With a hammer and anvil a bend is made by laying the heated metal on the anvil with part of the stock extending over the edge. The unsupported stock is struck with the hammer forcing it downward. Once the bend is started it might be continued on the face of the anvil with the end of the bend turned up: striking the outside of the bend will make it tighter and on the inside will open it. The bend might be refined by bracing the stock against the horn or the face and side of the anvil and striking the stock against these forms.
[edit] Punching
- Punching makes a depression or hole in the metal by driving a punch into or through the metal. Punching may be done to create a decorative pattern, or to make a hole. For example, in preparation for making a hammer head, a smith would punch a hole in a heavy bar or rod for the hammer handle. Punching is not limited to depressions and holes. It also includes cutting, or slitting and drifting.
[edit] Combining Processes
The five basic processes are often combined to produce and refine the shapes necessary for finished products. For example to fashion a cross peen hammer head a smith would start with a bar roughly the diameter of the hammer face, the handle hole would be punched and drifted, the head would be cut (punched, but with a wedge), the peen would be drawn to a wedge, and the face would be dressed by upsetting.
In the example of making a chisel, as it lengthened by drawing it would also tend to spread in width, so a smith would frequently turn the chisel-to-be on its side and hammer it back down -- upsetting it -- to check the spread and keep the metal at the correct width for the project.
As another example, if a smith needed to put a 90 degree bend in a bar and wanted a sharp corner on the outside of the bend, the smith would begin by hammering an unsupported end to make the curved bend. Then, to "fatten up" the outside radius of the bend, one or both arms of the bend would need to be pushed back into the bend to fill the outer radius of the curve. So the smith would hammer the ends of the stock down into the bend, 'upsetting' it at the point of the bend. The smith would then dress the bend by drawing the sides of the bend to keep it the correct thickness. The hammering would continue -- upsetting and then drawing -- until the curve had been properly shaped. In this case the primary operation was the bend, but the drawing and upsetting are done to refine the shape.
[edit] Welding
Welding is the joining of metal of the same or similar kind such that there is no joint or seam: the pieces to be welded become a single piece.
A modern blacksmith has a range of options and tools to accomplish this. The basic types of welding commonly employed in a modern shop include traditional forge welding as well as modern methods, including oxyacetylene and arc welding.
In forge welding the pieces to be welded are heated to what is generally referred to as "welding heat". For mild steel most smiths judge this temperature by color: the metal will glow an intense yellow or white. At this temperature the steel is near molten and just short of combustion.
Any foreign material in the weld, such as the oxides or "scale" that typically form in the fire, can weaken it and potentially cause it to fail. Thus the mating surfaces to be joined must be kept clean. To this end a smith will make sure the fire is a reducing fire: a fire where at the heart there is a great deal of heat and very little oxygen. The smith will also carefully shape the mating faces so that as they are brought together foreign material is squeezed out as the metal is joined. To clean the faces, protect them from oxidation, and provide a medium to carry foreign material out of the weld the smith will use flux -- typically powdered borax, silica sand, or both.
The smith will first clean the parts to be joined with a wire brush, then put them in the fire to heat. With a mix of drawing and upsetting the faces will be shaped so that when finally brought together the center of the weld will connect first and the connection spread outward under the hammer blows, pushing the flux and foreign material out.
The dressed metal goes back in the fire, is brought near to welding heat, removed from the fire, brushed, flux is applied, and it is returned to the fire. The smith now watches carefully to avoid overheating the metal. There is some challenge to this, because in order to see the color of the metal it must be removed from the fire, and this exposes the metal to air, which can cause it to oxidize rapidly. So the smith might probe into the fire with a bit of steel wire, prodding lightly at the mating faces. When the end of the wire sticks the metal is at the right temperature (a small weld has formed where the wire touches the mating face so it sticks).
Now the smith moves with rapid purpose. The metal is taken from the fire and quickly brought to the anvil, the mating faces are brought together, the hammer lightly applying a few taps to bring the mating faces into complete contact and squeeze out the flux, and finally returned to the fire again.
The weld was begun with the taps, but often the joint is weak and incomplete, so the smith will again heat the joint to welding temperature and work the weld with light blows to "set" the weld and finally to dress it to the desired shape.
[edit] Heat treatment
Other than to increase its malleability, another reason for heating the metal is for heat treatment purposes. The metal can be hardened, tempered, normalized, annealed, case hardened, and subjected to other processes that change the crystalline structure of the steel to give it specific characteristics required for different uses. Only steel, not iron, can be heat treated, and generally speaking, the higher the carbon content of the steel, the more it can be hardened.
When working with steels, a blacksmith will heat the metal and then quench it in various liquids such as water or oil. The purpose of quenching is to produce rapid cooling to generate specific microstructures in the metal. A quench from a bright red or orange heat generally results in steel that is hard and brittle, so a second process, called tempering, is usually done to increase the toughness of the piece and reduce its hardness.
Tempering involves heating the material to a specific temperature (lower than red heat) usually called "critical temperature" and judged for common steel by the temperature at which the metal loses its magnetic attraction. Sometimes it is quenched again after this heating.
With most tool steels, the degree of temper achieved can be gauged by the appearance of a colored oxidation tint on the metal surface. Different uses require different hardness and toughness combinations, and so receive different degrees of temper. It is possible to temper different parts of an object to different levels of hardness, which is one area where the skill of the blacksmith comes into play.
For example, the face of a hammer is often made harder than the main body, giving a blend of a hard wearing face with a resilient and tough head. Edged weapons, in particular, are often treated to provide a hard edge (which will retain sharpness with use longer) while keeping the main body of the blade tough to be more flexible and resist breaking from a powerful or jarring blow.
[edit] Finishing
Depending on the intended use of the piece a blacksmith may finish it in a number of ways:
- A simple jig that the smith might only use a few times in the shop it may get the minimum of finishing: a rap on the anvil to break off scale and a brushing with a wire brush.
- Files can be employed to bring a piece to final shape, remove burrs and sharp edges, and smooth the surface.
- The wire brush either as a hand tool or power tool can further smooth and brighten a surface.
- Grinding stones, abrasive paper, and emery wheels can further shape, smooth and polish the surface.
- There are a range of treatments and finishes to inhibit oxidation of the metal and enhance or change the appearance of the piece. An experienced smith selects the finish based on the metal and intended use of the item.
- Finishes include but are not limited to: paint, varnish, blueing, browning, oil, and wax.
[edit] The blacksmith's materials
When iron ore is smelted into usable metal, a certain amount of carbon is usually alloyed with the iron. The amount of carbon has extreme effects on the properties of the metal. If the carbon content is over 2%, the metal is called cast iron. Cast iron is so called because it has a relatively low melting point and is easily cast. It is quite brittle however, and therefore not used for blacksmithing. If the carbon content is between .25% and 2%, the resulting metal is tool steel, which can be heat treated as discussed above. When the carbon content is below .25%, the metal may be called either "wrought iron" or "mild steel." The distinction between wrought iron and mild steel is one of the manufacturing process and the end use, and the terms are sometimes interchangeable. In pre-industrial times, the material of choice for blacksmiths was wrought iron. This iron had a very low carbon content, and also included up to 5% of glassy slag. This slag content made the iron very tough, gave it considerable resistance to rusting, and allowed it to be more easily "forge welded," a process in which the blacksmith permanently joins two pieces of iron, or a piece of iron and a piece of steel, by heating them nearly to a white heat and hammering them together. Forge welding is more difficult to do with modern mild steel. Modern steel production, using the blast furnace, cannot produce true wrought iron, so this material is now a difficult-to-find specialty product. Modern blacksmiths generally substitute mild steel for making objects that were traditionally of wrought iron.
[edit] The Blacksmith's Tools
Over the centuries blacksmiths have taken no little pride in the fact that theirs is one of the few crafts that allows them to make the tools that are used for their craft. Time and tradition have provided some fairly standard basic tools which vary only in detail around the world.
"All a smith needs is something to heat the metal, something to hit the metal on and something to hit the metal with."
The forge is the fireplace of a blacksmith's shop. It provides the means to keep the fire contained and controlled.
The anvil at its simplest is a large block of iron or steel. Over time this has been refined to provide a rounded horn to facilitate drawing and bending, a face for drawing and upsetting and bending, and one or more holes to hold special tools (swages or hardies) and facilitate punching. Often the flat surface of an anvil will be hardened steel, and the body made from tougher iron.
Blacksmiths' hammers tend to have one face and a peen. The peen is typically either a ball or a blunt wedge (cross or straight peen depending on the orientation of the wedge to the handle) and is used when drawing.
While a great deal of work may be done with those three basic tools blacksmiths tend to augment their tools with some of the following, depending on the kinds of work they do.
Tongs are used to hold the hot metal. They come in a range of shapes and sizes.
Swages (hardies) and fullers are shaping tools. Swages are either stand alone tools or fit the "hardie hole" on the face of the anvil. The metal is shaped by being driven into the form of the swage. Opposite to the swage in some respects is the fuller which may take a number of shapes and is driven into the metal with a hammer. Swages and fullers are often paired to bring a piece of metal to shape in a single operation, essentially a set of dies. A fuller and swage pair might be spoon shaped, for example, the swage dished to form the bowl and the fuller the convex mirror of the swage. Together they will quickly stamp a spoon shape on the end of a bar.
There are many other tools used by smiths, so many that even a brief description of the types is beyond the scope of this article and the task is complicated by a variety of names for the same type of tool. Further complicating the task is that making tools is inherently part of the smith's craft and many custom tools are made by individual smiths to suit particular tasks and the smith's inclination.
With that caveat one category of tools should be mentioned: jigs. A jig is generally a custom built tool, usually made by the smith, to perform a particular operation for a particular task or project. For example, a smith making decorative scrolls for an iron fence will make a bending jig, or scroll iron, to apply a particular shape to the stock, ensuring that each scroll has the same bend. (To estimate the length of stock required to form a scroll of any given size and number of turns the Clackson scroll formula is used.)
[edit] History and the present
Prior to the industrial revolution, a "village smithy" was a staple of every town. Mass production techniques have reduced the marketplace for blacksmith work except in Africa, India, Southeast Asia, and South America where large numbers of artisans continue to do traditional work. In more industrialized regions, an increasing demand for custom metalwork has given rise to a new breed of smiths commonly known as Artist-Blacksmiths. In recent years the forging of stainless steel has given rise to a fresh approach to architectural blacksmithing.
One famous blacksmith, albeit a mythical one, was Hephaestus (Latin: Vulcan). He was the blacksmith of the gods in Greek and Roman mythology. A supremely skilled artisan whose forge was a volcano, he constructed most of the weapons of the gods, and was himself the god of blacksmiths, craftsmen, artisans, sculptors, metallurgy and fire.
[edit] See also
- Forge
- Philip Simmons, Artist-Blacksmith
- Saint Dunstan
- George Fayerweather
- Worshipful Company of Blacksmiths
- Bladesmith
- Weyland An Anglo-Saxon smith-god
[edit] External links
- The Post-Apocalyptic Blacksmith
- IForgeIron.com Blacksmithing Forum, Gallery, Blueprints, and Chat
- The Artist Blacksmith's Association of North America
- Anvilfire.com Blacksmithing and Metalworking Reference
- Modern Blacksmithing By J.G. Holmstrom 1901
- Video Victorian Blacksmith at work
- Blacksmiths keep Boston's transit system rolling
- Royal Naval Museum - Sea Your History - Blacksmiths Discusses the work of the Royal Navy's blacksmiths.
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