Drum

Background

A drum is a musical instrument which produces sound by the vibration of a stretched membrane. The membrane, which is known as the head, covers one or both ends of a hollow body known as the shell. Instruments that produce sound by means of a vibrating membrane are also known as membranophones. Drums are part of the larger category of musical devices known as percussion instruments. Percussion instruments other than membranophones are known as idiophones. Idiophones, such as bells and cymbals, produce sound by the vibration of the instrument itself rather than by an attached membrane.

Drums exist in a wide variety of shapes and sizes. The two basic shapes for shells are bowls and tubes. The most familiar bowlshaped drums in Western music are kettledrums, also known as timpani. Tubular drums may be taller than they are wide, such as conga drums, or shorter than they are wide. Short drums, also known as shallow drums, are the most common tubular drums used in Western music. Shallow drums include snare drums, tenor drums, and bass drums. If a tubular drum is so shallow that the shell does not resonate, it is known as a frame drum. The most familiar type of frame drum is the tambourine.

Drums are usually played by being struck. Some drums, such as bongo drums, are designed to be played by striking them directly with the hand. In modern Western music, most drums are designed to be played by being struck with various devices known as beaters. The most familiar beaters are wooden sticks, generally used to play smaller drums such as snare drums, and padded wooden mallets, used to play larger drums such as bass drums. Sometimes drums are struck with wire brushes or other types of beaters to produce a different sound.

Some drums, particularly in non-Western cultures, are played in ways other than being struck. Rattle drums contain pellets within the shell or knotted cords attached to the head and are played by being shaken. Friction drums are played by being rubbed. Some membranophones have the vibrating membrane set into motion by sound waves coming from a human voice or from another musical instrument. These devices are known as mirlitons. The most familiar mirliton is the kazoo.

Drums are either tunable, so that they produce a particular note, or nontunable. Most drums in Western music are nontunable. The only commonly used tunable drums in Western music are timpani. Idiophones, which exist in an even greater variety than membranophones, may also be tunable, such as a xylophone, or nontunable, such as a rattle.

History

Percussion instruments have been used since prehistoric times. The earliest drums consisted of fish or reptile skin stretched over hollow tree trunks and were struck with the hands. Somewhat later the skins of wild or domesticated mammals were used to make larger drums which were struck with sticks. Besides tree trunks, skins were also stretched over pits dug into the ground to make large drums or over openings in pots or gourds to make small drums.

Frame drums were used by the ancient civilizations of the Middle East about 5,000 years ago. They were later adapted by the ancient Greeks and Romans. The Romans also used tubular drums with skins stretched over both ends of a hollow shell. After the fall of Rome, drums were not commonly used in Western Europe, although they continued to be used by the Arabs. The Crusades brought Europeans in contact with the Arab culture. From the Arabs, Europeans adapted the tambourine (a small frame drum), the naker (a small kettledrum), and the tabor (a small tubular drum). The tabor was often used with a snare, which consisted of thin cords of animal gut stretched across one of the heads in order to produce a rattling sound. The snared tabor is the ancestor of the modern snare drum.

Large kettledrums, long used in the Middle East, were introduced to Western Europe in the fifteenth century. These instruments consisted of calfskin stretched over large copper cauldrons and were used for military and ceremonial purposes. They were first used in orchestras in the late seventeenth century.

The bass drum, a large tubular drum, was rare in Europe until the late eighteenth century. The snare drum and the tenor drum (a somewhat larger version of the snare drum, but without the snare) were used primarily for military purposes until the nineteenth century.

Timpani became an important part of orchestral music during the nineteenth century. During the 1880s, devices were developed which allowed timpani players to change the pitch of the instrument quickly, allowing them to play more complex melodies.

An important development in drum manufacturing occurred in the 1950s when drum makers began to experiment with using plastic instead of animal skin to make heads. Although some drummers, particularly timpani players, preferred the sound of heads made with animal skins, plastic heads soon almost completely replaced traditional heads. A few individual drum makers still make heads from animal skins for musicians who prefer this type of product.

During the twentieth century, percussion instruments of all kinds became important in both orchestral music and in popular music. A modern drum set used by popular musicians such as jazz and rock drummers often consists of a bass drum struck with a mallet operated by a foot pedal, a snare drum, a series of tubular drums of various sizes, and a set of cymbals.

Raw Materials

Until the late 1950s, the head of a drum was almost always made of animal skin. Modern heads are now almost always made of plastic. Usually some form of polyester is used. Polyesters are plastics in which numerous small molecules are linked together into a long chain using a chemical bond known as an ester group. The most common form of polyester used in the drum industry is known as polyethylene terephthalate, available under trade names such as Mylar. Polyethylene terephthalate has the advantage of being strong and resistant to moisture, heat, sunlight, and many chemicals. Polyethylene terephthalate is made from the chemical compounds ethylene glycol and terephthalic acid. These substances are derived from petroleum

The shell of a drum is usually made of wood. Commonly used woods include maple, birch, and poplar. Some drums have a shell made of metal. Commonly used metals include steel, aluminum, brass, and bronze. Sometimes synthetic materials are used to make shells. These materials are usually strong, hard plastics.

The various hardware components that hold the drum together are usually made of steel. Sometimes other metals such as brass or aluminum are used. In some cases, these components are made of wood or strong plastic.

Optional attachments such as stands to hold the drum in front of the drummer are usually made of steel or aluminum. Straps to hold the drum in place while marching in a band are generally made from leather, plastic, or cloth. The snare of a snare drum consists of thin strands of various materials such as steel, aluminum, plastic, or animal gut.

The Manufacturing
Process

Making the hardware components

• 1 Metal hardware components are made using precision metalworking equipment
  

  Drum head material is made by cooling hot liquid plastic on a large metal roller to form a solid, then stretched between smaller metal rollers to produce a thin film.
  such as drills and lathes. Wood hardware components are carved from blocks of wood using various kinds of cutting instruments. Plastic hardware components are often made using a process known as injection molding. This process involves heating the plastic until it melts, injecting the molten plastic into a mold in the shape of the desired component, allowing the plastic to cool back into a solid, opening the mold, and removing the completed component.

Making the head

• 2 Polyethylene terephthalate is made by combining terephthalic acid (or a derivative such as dimethyl terephthalate) with ethylene glycol. These chemicals are subjected to heat to produce hot, liquid plastic. The liquid is cooled on a large metal roller to form a solid, then stretched between smaller metal rollers to produce a thin film. Various additives may be included to produce films in many colors, which may be either transparent or opaque.
• 3 The polyethylene terephthalate film is shipped to the drum manufacturer on large rolls. Circles of the proper sizes to make drum heads are cut from the film using precision cutting tools.
• 4 The edge of the plastic circle is softened by a heating element and allowed to cool to form a collar around the circumference. A steel ring is placed within the collar and an aluminum ring is placed outside the collar. The ring is then closed on a rolling machine to produce a tubular, secure circle of metal, which serves to keep the plastic skin taut. The completed head is stored until needed for assembly.

Making the shell

• 5 Metal shells are made using a variety of methods including casting (pouring molten metal into a mold in the shape of the shell) and machining (shaping the metal with various metalworking machines such as drills and lathes). Plastic shells may be made using injection molding.
• 6 Most shells are made of wood. Wooden shells are made from large, thin panels of wood known as veneer. Veneer is cut from lumber with large saws and shipped from the lumber company to the drum manufacturer.
• 7 Veneer is cut to the proper size to make the shell by a computer-controlled saw. The cut pieces of veneer are sorted by size and stored under controlled temperature and humidity until needed.
• 8 Pieces of cut veneer of the proper sizes are moved through a glue press. This device applies glue to the veneer as it passes
  

  Schematic diagram of the formation of the plastic drum heads.
  between large metal rollers. The pieces of veneer are then rolled together to form a cylinder consisting of about 7-9 layers of veneer. The rolled veneer is inserted into a metal mold of the proper size to make the desired shell.
• 9 A variety of methods exist to apply pressure to the glued layers of veneer within the mold. A bag within the mold may be inflated to apply pressure. Water or oil may also be used to apply pressure. The glue may be allowed to dry slowly on its own or an electrical current may be applied to dry the glue quickly.
• 10 The shell is removed from the mold. It is then cut with a rapidly rotating blade to produce a 45° angle on its edge. In other words, the layers of veneer are cut at slightly different heights, with the innermost layer being the shortest and the outermost layer being the tallest. This sloping edge will allow the head to fit in place.
• 11 The shell is sanded with high power sanders to produce a smooth surface. It is then either stained or covered with a sheet of shiny, decorative plastic in various colors and patterns. If it is stained, it is rotated while wood stain of various colors is sprayed on it. The stain is then dried quickly with ultraviolet light. A clear, shiny topcoat is then applied and dried in a similar way.

Assembling the drum

• 12 Precision drills are used to drill holes in the shell to allow the hardware components to be attached. Lugs, which hold the head in place, are screwed into the shell. Long, thin metal rods known as tension rods pass through the aluminum ring surrounding the head and into the lugs. The degree of tension on the head can be controlled by using a drum key, which tightens or loosens the tension rods.
• 13 For a snare drum, a small amount of one edge of the shell is cut away to allow the snare to fit in place so that it touches one of the heads. The snare is attached in such a way that it can either be held tight, producing the snared sound, or held loose, producing the unsnared sound.

Packaging and shipping

• 14 The drum is placed in a plastic bag. It is then placed in a cardboard box containing pieces of expanded polystyrene foam, a firm, light plastic that prevents the drum from moving during shipping. The boxes are then shipped to musicians, music stores, orchestras, marching bands, and other consumers.

Quality Control

The most important factor in the quality control of drum manufacturing is the size and shape of the various components. The wooden veneer must be cut to the precise size to allow several layers to fit together to form a cylinder. The plastic head and the metal rings that hold it in place must fit together properly. The lugs and other hard-ware components must be positioned correctly in exact holes drilled in the proper places in the shell.

The external appearance of the drum is important to drummers. Each drum is visually inspected to ensure that the wood stain or decorative plastic wrapping is free from defects.

The Future

During the 1980s, it seemed that electronic drum machines (flat panels that produce a synthesized sound when struck) might replace traditional drums in popular music. It soon became obvious that drummers preferred playing traditional drums. In the future, small electronic devices may be attached to drums to allow the sound to be manipulated in new ways while allowing the drummer to enjoy the experience of playing traditional drums.