How Pool Tables Work

Pool is played on a table with a cue and balls, and relies heavily on physics and geometry.  This article will discuss how pool tables work, including the various components of a pool table, and how they work together.

Most pool tables are made using a large piece of slate.  Slate is a rock that naturally splits into wide, flat pieces.  Most other materials used for making pool tables, such as synthetics (Slatron and Permaslate), honeycomb, or particle board (also called Medium Density Fiberboard or MDF), will warp and are unable to remain completely flat.  Slate, however, is highly resistant to warping and will last for years if not generations.  While Italian slate is generally regarded as the most premium material from which to build a pool table, Brazilian slate has also developed a fan base in recent years.

Because slate is large and heavy (up to 600 lbs. for a standard-size table), it is typically separated into three pieces.  This reduces the cost of transporting the table and makes it easier to transport.  Most three-piece slates available are diamond-honed matched and registered, which simply means that all three sections were cut from the same slab of slate. Diamond-honing results in a smooth, level playing surface. A professional installer can ensure that all three pieces are assembled in such a way that they match perfectly and the table is completely flat.

The slate should be larger than the actual playing surface, extending beneath the rails of the table, making the table stronger.  The slate should ideally be framed as well.  The frame is typically made of wood and glued to the bottom of the table.  This way, once the green felt cloth is stretched over the table, it can be stapled to the frame, rather than glued to the slate directly.

The table cabinet is a large wooden frame, rectangular in shape and made from planks of thick hardwood.  Designs can vary, but typically the slate is supported by one or two cross beams, as well as a center beam.  Metal brackets are used to connect the corners.  The number of table legs will vary from four to eight, depending on the size and weight of the table.  In some cases, instead of standard legs, the table uses two large ‘pedestal’ style legs.  For the best support, the legs should extend all the way up to the underside of the slate, not just to the bottom of the frame.

The type of wood used to make the cabinet can vary, depending on the quality of the table.  While some inexpensive tables use particle board covered by a plastic or thin hardwood finish, a slate table usually requires a table made from solid wood.  As previously mentioned, as slate tables typically weigh in the hundreds of pounds,  a strong frame is necessary to support it.  Furthermore, solid wood has a much greater capacity for holding screws.  As the table is screwed or bolted together, the table material must be able to hold those screws tightly or the table will not stay rigid. Commercial tables will often have sheets of metal, such as aluminum, attached to the surface of the wood frame for protection.

Pool tables have drop pockets.  This means there are usually nets under each pocket to catch any balls that enter.  Commercial tables often have a ball return system.  Chutes are connected to each of the table’s pockets, and are arranged in such a way that gravity will roll the ball down to its intended location.   The pocketed balls are sent to a collection chamber, which is visible to an outsider through plexiglass.  When a player inserts a coin, a switch is activated that enables the balls to roll out into the access area at the foot of the table.

You might be wondering about the cue ball.  If a cue ball is pocketed accidentally, this is called a scratch and the cue ball must be returned to the players.  A commercial table, therefore, requires some way of identifying which ball is the cue ball.  This is accomplished using one of two methods.  One method is to make the cue ball slightly larger than the other balls.  The table then utilizes a mechanism to detect the larger size, and send the ball down a dedicated chute.  Another method is to use a magnet inside the cue ball.  This ball triggers a magnetic detector inside the table, enabling it to be separated from the other balls.

Both systems have their disadvantages.  A larger ball can hamper the play of some advanced players who are accustomed to using a standard-size ball.  A magnetic ball, however, can occasionally exhibit strange behavior when rolling.  A magnetic ball is also easier to shatter if dropped on a hard surface.

Rails are found around the edges of the table, and are made from two pieces.  The top piece is typically made from particle board or solid wood.  Solid wood is the preferred choice, and this is because cushions are glued to the side of the rails.  Cushions are made of hard rubber, and after several years they may need to be replaced.  When replacing a cushion, a top rail made from particle board will often chip and crack, making it unusable.  Solid wood top rails, however, do not suffer from this problem.  Also, as the green cloth covering the board is stapled to the rails, solid wood is preferred because it holds the staples better.  Balls also rebound better off solid wood rails, making gameplay livelier.

With regards to the previously-mentioned cushions, their purpose is to cause the balls to rebound off the rubber while minimizing the loss of kinetic energy.  Good cushions have several important characteristics.  First, the cushions should be K-66 cushions. K-66 is a term used to describe the cushion’s shape and angle, and is the American standard.  Second, the cushion should ideally be backed with canvas, which not only helps adhere the cushion to the rail, but also helps control the action on the table and make it more predictable.  Grade A rubber is also ideal for the best rebound quality.

The apron, also known as the skirt, is the wood which mounts vertically from the rail. The purpose of the apron is to cover the raw edge of the slate and the staples which attached the cloth to the slate.

The afore-mentioned cloth, usually green, covers the table.  While it is often called the felt, it is actually a woven material.  A wool/nylon blend is ideal, usually 80% wool and 20% nylon.  This should play well and also wear well over time.  As mentioned previously, however, the cloth will likely need to be replaced after several years of play.

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