English Wheel - Construction

Construction

The machine is shaped like a large, closed letter "C". At the ends of the C, there are two wheels. The wheel on the top is called the rolling wheel, while the wheel on the bottom is called the anvil wheel. (Some references refer to the wheels by their position: upper wheel and lower wheel.) The anvil wheel usually has a smaller radius than the rolling wheel. Although larger machines exist, the rolling wheel is usually 8 cm (3 inches) wide or less, and usually 25 cm (9 inches) in diameter, or less.

The rolling (top) wheel is flat in cross section, while the anvil (bottom) wheel is domed.

The depth of the C-shaped frame is called the throat. The largest machines have throat sizes of 120 cm (48 inches), while smaller machines have throat sizes of about 60 cm (24 inches). The C stands vertically and is supported by a frame. The throat size usually determines the largest size of metal sheet that the operator can place in the machine and work easily. On some machines, the operator can turn the top wheel and anvil 90 degrees to the frame to increase the maximum size of the work piece. Because the machine works by an amount of pressure between the wheels through the material, and because that pressure changes as the material becomes thinner, the lower jaw and cradle of the frame that holds the anvil roller is adjustable. It may move with a hydraulic jack on machines designed for steel plate, or a jackscrew on machines designed for sheet metals. As the material thins, the operator must adjust the pressure to compensate.

Frame designs are the most significant element of this simple device. For the most part however, wheels have changed very little since the 19th century. The early English machines (as opposed to the American versions), such as Edwards, Kendrick, Brown, Boggs, and Ranalah, etc., had cast iron frames. These wheels, made during the 19th Century, had Babbitt metal plain bearings in them, making them a little difficult to push and pull the metal through when operated at high pressures. Later, when ball-and-race bearings came into use, the machines became more suitable for hard and thick material, such as 1/8” steel. Despite the advantages of cast iron, it has less than half the stiffness (Young's modulus) of steel, and therefore, sometimes must be replaced by steel when a stiffer frame is needed. Steel frames made of solid flame-cut plate, or frames built-up of cut-and-welded plates, are common designs. Steel tubing, generally of square section, has been used for wheeling machine frames during the past 30 years, in the US particularly, where sheet metal shaping has become a hobby as well as a business. Tube-framed machines are reasonably-priced and are available either as kit-built machines (or can be built easily from plans). The stiffest tubular frames have a fully triangulated external bracing truss. They are most effective on thinner or softer materials, such as 20 ga steel or .063" aluminum. Cast frame machines like the one pictured, are still available.

A properly equipped machine has an assortment of anvil wheels. Anvil wheels, like dollies used with hammers in panel beating (which are also known as anvils) should be used to match the desired crown or curvature of the work piece.