Forging

The Fire
The Anvil
The Hammer
Basic Techniques
Other Equipment

The first few sessions are spent orienting students to the forge space, equipment, safety, and basic blacksmithing techniques. MIT's blacksmithing lab contains three coal forges and six anvils, a coal bin, storage for tools, stock, and finished pieces, and a cutoff wheel and wire brush tool for finishing. It shares space with the MIT Glass Lab.

The Fire

A rolled ball of newspaper 8" wide, in a rectangular depression in the forge, surrounded by coal that's been shoveled out of the way. Yellow-tinged smoke rises from the center of the forge, where the newspaper has been covered with coal. Small flames rise from the newspaper and coal. Smoke from the offgassing coal surrounds a large fire. These flames are quite large and tall.

To light the forge, place a ball of newspaper in the fire pot, light it, turn on the blower, and cover with coal. Take care not to smother the flames, and/or make sure the airflow is sufficient. As the coal heats up, it will start to offgas. The exhaust should be taken up by the hood, not released into the room, as it contains sulfur dioxide and other hazardous materials. Too much airflow tends to blow the fumes away from the exhaust and into the room. Eventually, flames should start poking through the coal bed. From here, you can add more coal, rearrange the coals, and turn the airflow up or down to build a fire of the desired size and temperature.

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The Anvil

An orange Vulcan anvil, chained and bolted to a metal block. The top of the anvil, which has a small round and larger square hole in the large face, a smaller face stepped down from the large face, and then the rounded horn.

The anvils are mounted on heavy stands, to raise them up to a comfortable level and provide extra stability. Each anvil has a curved horn, which can be used to guide curves and widen holes; a flat top, for creating flat faces and bending angles; and a hardy hole for holding various accessories.

The curved top of the tool is 4" across and 1" tall, and has circular symmetry. The hardy has a triangle profile, and comes to a relatively sharp point at the top. Here it is cutting off a red-hot bottle opener. A 6" curved horn tapers from 1" across to a point. The end holding the workpiece is flattened to provide good contact, then it curves up and over to fit into the hardy hole.

For forming a curve in two dimensions at once, this form is useful. A hardy (cut off tool) is helpful for making notches or cutting off a piece. To create smaller-scale holes, this hardy horn can be used. When an extra hand is needed to hold a punch or other tool, the hold-fast can be hammered into the pritchel hole to keep the workpiece steady.

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The Hammer

A hammer held with the thumb along the handle. A hammer held with the thumb around the handle.

Once the fire is hot, it's time to hammer. Which hammer to use depends on the project. In general, hammers should be light enough that you can swing them easily and with sufficient control for a few hours at a stretch. Some smiths grip with their thumbs pointed along the handle, others prefer to keep it out of the way. When hot metal is hammered, metal flows out from the point of impact, so the shape of the hammer head affects the shape of the deformation created in the workpiece.

Photo of a cross-peen hammer. Close-up of the cross-peen head. Photo of a straight-peen hammer. Close-up of the straight-peen head. Photo of a double-peen hammer. Close-up of the wider peen face. Close-up of the narrower peen face. Photo of a ball-peen hammer. Close-up of the ball-peen head.

This cross-peen hammer has a round face at one end, to spread evenly in all directions, and a blunt wedge (peen) on the other, to lengthen the metal in one dimension only. The straight-peen is similar, but the wedge is parallel to the handle, rather than perpendicular. This hammer has two different peen widths on its head, to confine the impact to a smaller or larger area as needed. This ball-peen hammer has a flat face and a hemispherical peen, to allow simultaneous isotropic spreading in the plane and curving up out of the plane.

Photo of a wooden mallet. Photo of a bronze mallet. Close-up of the bronze mallet face, which shows many deep dents and scratches. Using a wooden mallet to hammer a metal twist on a tree trunk.

Hammers with wood or bronze heads are used when force needs to be applied without deforming the metal surface. The soft faces are therefore deformed instead. They should be used with a soft surface, like a wooden block.

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Basic Techniques

A rectangular chunk of grey clay is smashed at one end by hand, to demonstrate how hammer blows deform hot metal. The left end of the clay has a symmetric taper and the right has a taper that's been rolled up into a spiral.

To demonstrate how metal acts, a chunk of clay is drawn and pointed. First, square up the faces by laying it on the anvil flat and hammering, then rotate 90° and repeat until all the faces are flat. To draw a taper, hammer starting from a few inches from the end, all the way to the end of the piece. To maintain a constant width, turn it 90° periodically, making sure to square up the sides when they show irregularities. To make a point, tilt the piece up to half the desired angle, so the anvil and hammer faces act on both sides at once. Here, the clay has a taper on one end and a scroll on the other. Tapers can be formed in two directions, by flipping the piece 90 degrees every so often. Students were allowed to experiment with the clay before picking out pieces of metal to start practicing with.

A thin taper has the last half-inch bent over the edge. A little more has been bent down, and the next inch or two is heated to follow along. The workpiece is turned face-up, and the curve is hammered down and back. Instead of trying to wind the scroll as tight as it can go with a hammer, it's easier to hang it over the edge of the anvil face and hammer on the outside of the scroll, letting the side of the anvil exert the necessary force. A tapered bar with two right-angle bends roughly an inch apart, forming a hook that could be hung over a door, for example. Having added another turn to the scroll, the side of the anvil is used again to tighten it all up. Heating successive sections of the stock and rolling them up can create quite large scrolls.

After drawing a taper, bending it into a corner or scroll is a common next step. Here, the edge of the anvil is used to put a start the bend. After another heat, the piece is hammered back onto itself. If the end needs to be tucked in tightly, the edge of the anvil can be used as a fulcrum. If not, the edge can be used to put a series of sharp bends in the metal. After the spiral has started, it can be rolled up as far as desired.

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Other Equipment

Metal tongs look like pliers with longer handles and less pointed jaws. An S-shaped piece of metal, with the ends of the S being quite long, and the curves being quite tight, roughly the same width as the bar. A metal bar is clamped in a vise, and tucked into one curve of the S, which twists it as the long handles are turned around. The finished twist may be tight or loose, depending on how fast the curve is cranked, how much metal was heated, and how much was free outside the clamp.

Many accessories have developed to make blacksmithing easier and safer. All students are required to wear safety goggles, closed-toed shoes, and have no dangling clothing or hair. Tongs and/or leather gloves help grip small workpieces. To put twists in square or bar stock, heat the piece in the area to be twisted, then brace it in a press. Apply the S-curve above the heated area and twist evenly but quickly. Stop when the metal is noticeably cooled.

Punches are 6" long, 1/2" wide, and have a flat head for hammering. This one is square-sided, and the end is a straight point the width of the stock. This punch is round, and tapers to a round point. Another chisel punch, with a sharper taper. Another round punch, which tapers slightly before cutting off flat, leaving a face roughly 1/2" wide.

Punches come in a variety of shapes and sizes, and can be used to create surface detail as well as punching holes. The tip is hardened and tempered while the body and head are left soft to withstand force without shattering.

Coarse wire bristles scrub the surface of a red-hot workpiece. A drill press with a rotating wire brush scrubs rust off a bottle opener. A piece of bar stock is clamped in a vise and the ragged end is sawed off.

A wire brush removes iron oxide (scale) and other debris from the workpiece before it goes back into the fire. The wire brush wheel is useful for removing iron oxide from finished pieces, for a cleaner surface finish. One way to cut metal to length, either before or after forging one end, is with a hacksaw.

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