From classical symphonies to death metal, drums are an integral part of almost all music created across the globe. The drum belongs to the family of percussion instruments and they mostly consist of stretched membrane (referred to as head) covering one or both ends of the drum’s hollow body, which is referred to as shell. Sound is produced by the drum when the stretched membrane is vibrated.
To produce music, most drums have to be rhythmically struck with various devices. Bongo drums are struck manually while others are struck by beaters. Beaters such as wooden sticks are mainly to play smaller drums, while padded wooden mallets are used to play larger drums. Wire brushes are used to produce different sound.
Numerous types of drums in various shapes and sizes are used around the world. The most commonly used is the modern drum set, which consists of drum head, drum shell, tension rod, tension rod washers, rim, and mounting lugs. Another integral part of the standard drum kit is the cymbal. Cymbals and bells produce sound by self-vibration method without the use of a membrane.
The range of materials used to create the modern drum kit is large and varied and is outlined in more detail below.
Raw Materials
The raw materials used in the manufacture of drums has changed remarkably over the last century. Take drum heads - until the 1950s drum heads were predominately made of animal skin, but today the majority are formed from plastics such as polyester or Mylar. The most common form of polyester that is used is polyethylene terephthalate, due to its strong nature and resistance to moisture, heat and sunlight. Polyethylene terephthalate is composed of chemical compounds -ethylene glycol and terephthalic acid, substances derived from petroleum.
Drum shells are chiefly made from birch, maple, and poplar wood, though metal and synthetic variations are also available now and are taking over in some respects. Steel, aluminum, brass, and bronze are regularly used in the construction of these and plastic is used in synthetic shells.
Drum hardware is a generic term used for equipment needed to posititon and support the drum, and some parts can also act as a tonal adjusters. Brushed aluminum is the material often used and mounting lugs are made of die-cast metal such as steel. Other various parts of hardware can be created from brass, wood and strong plastic. Drum rims or hoops are made from both metal and wood. Metal rims are made of die-cast aluminum and wooden rims are made from maple or birch.
Cymbals are mostly made from a casting of tin, copper, and silver. According to the weight, the castings are shaped in a rotary oven burning at about 815°C (1499°F). The softened metal is then rolled and flattened.
The cymbal is cut to a particular diameter, and hammered by a hydraulic cylinder. A computer program monitors the hammering force and distributes it evenly. The dents formed on the metal help produce excellent sound due to the changing path of the sound waves. Tonal grooves with varying depth and position are then carved into the cymbal. An edging machine completes the process by smoothing out the edges.
Manufacturing Process
Due to the large number of material components used in drum kits, the manufacturing processes required to create a full drum kit are rather complex. In general, metal hardware parts of the drum are made using precision metalworking equipment and wood hardware components of the drum are carved out of wood blocks using cutting instruments. Plastic hardware components of the drum are made using injection molding process where plastic is heated to melting point and injected into a mold of desired shape. The plastic is cooled until it solidifies and then the mold is removed. These manufacturing methods are outlined in more detail below.
To Make the Head
Polyethylene terephthalate is made by combining terephthalic acid with ethylene glycol. The chemicals are heated to produce liquid plastic. On cooling, it solidifies and is stretched between smaller metal rollers to produce a thin film. To add color to the film, some additives are included. The film is dispatched to a drum manufacturer in huge rolls, where circles of appropriate size are cut from the film using precision cutting tools to form a drum head. The edge of the plastic circle is softened by a heating element and then cooled to form a collar around the circumference. Following this an aluminum ring is placed outside the collar and a steel ring is placed within the collar. These rings help keep the plastic skin taut.
To Make the Shell
Casting and machining methods are commonly used to make metal shells while injection molding is used to make plastic shells. However, wooden shells are more popular. These shells are made from large, thin panels of veneer, a type of wood. The drum manufacturer cuts the veneer to proper size using a computer-controlled saw. The pieces are grouped based on size and stored in controlled temperature and humidity environment. The pieces are then sent through a glue press, which applies glue. Later, about 7 - 9 layers of veneer pieces are rolled into a cylindrical shape and inserted into a metal mold of desired size.
It is important to apply pressure to the glued layers of veneer within the mold. For this, a bag within the mold is inflated to produce the required pressure, or water or oil is used. The glue is either allowed to dry on its own or by using electrical current for quicker effect. After the shell is taken out of the mold, it is cut with a rapidly rotating blade that gives a 45° angle to the edge such that the innermost layer is the shortest and the outermost layer is the tallest. The head can be fitted to the sloping edge. For a smooth and decorative shell surface, it can be sanded with high power sanders and covered with shiny sheet of plastic, or it can be wood stained with various colors and dried with UV light and a shiny topcoat is finally applied.
To Assemble the Drum
The hardware components are fitted onto the shell using precision drills. The following are the key components:
- Lugs are screwed into the shell so as to hold the head in place
- Tension rods are passed into the lugs via the aluminum ring that surrounds the head
- A drum key is required to control the degree of tension on the head by tightening or loosening the tension rods.
Innovations in Drum Materials
The world’s only Corian-made drum kit created by Craig Cockrell of England is changing the material format usually associated with drum making. Corian is a mixture of natural minerals, aluminium and acrylic. It is hand crafted in about 16 to 18 h, and Cockrell is taking orders from around the world. The material is thick with excellent acoustic properties and provides good structural quality that enhances projection of sound.
Another innovative version is the electronic drum. It acts as electronic synthesizer and mimics an acoustic drum kit. This drum comprises a set of pads that are fitted on a stand. The pads are rubber or cloth-like coated discs. When a pad is struck, the sensor contained within the pad generates an electric signal. The signal is then transmitted via cables into an electronic module to produce a particular sound matching the selected pad. Whether this could ever replace a traditional acoustic drum in a live setting however remains to be seen.
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