How Baseball Bats Work

Early amateur baseball players carved or whittled their own bats, or hired carpenters to fashion them from slabs of various hardwoods, but in a pinch, they were known to improvise. When the Philadelphia Athletics broke all their bats in a high-scoring 1865 game, they resorted to using a shovel handle to finish their at-bats [source: Kerr]. It wasn't until the late 1800s that sporting goods manufacturers, picking up on the game's rising popularity, began to mass-produce bats.

In 1884, J.A. "Bud" Hillerich, an apprentice woodworker in Louisville, Ky., went to see his local team, the Louisville Eclipse. When star slugger Pete Browning broke his bat during the game, Hillerich invited him back to the shop and spent all night making him a personalized one. After he used it the next day to get three hits, the famed Louisville Slugger brand was born [source: Morrison].

Roughly a decade later, professional baseball rule-makers, standardized the bat, deciding that it had to be:

They didn't specify a maximum weight. That led some early would-be power hitters to heft bats resembling tree trunks [source: Hill].

The type of wood used in bats evolved over the years as well. Initially, bat makers sometimes used hickory, but they eventually gravitated toward white ash, which was lighter but still durable. In 2001, after the San Francisco Giants' Barry Bonds used a bat made of maple to hit a single-season record of 73 homers, that wood became very popular. By 2013, about half of players had switched to maple [sources: Dewey, Roberts, Morrison].

Maple bats are more flexible than ash and create a whipping action that drives the ball farther, but there's a downside: They have a greater tendency to shatter, sending dangerously sharp shards of wood into the field. (While Shoeless Joe Jackson used a single bat for 13 seasons in the early 1900s, today's players seldom get more than a month out of their bats [source: Dewey].)

In an effort to reduce the risk, Major League Baseball has banned softer, lower-density varieties of maple that are most likely to break, and reduced the width of the bat's barrel to 2.61 inches (6.6 centimeters) in diameter, to limit bat makers from producing thick bats with disproportionately thin handles [source: Roberts].

When a power hitter whacks a pitcher's fastball and knocks it into the upper deck, the actual amount of time that the ball comes in contact with the bat is just 0.7 milliseconds, according to Pennsylvania State University physicist Daniel A. Russell.

But while that game-changing event is brief, it's also filled with incredibly powerful and fast forces. Consider that a Major League baseball, which weighs a fraction more than 5 ounces (141 grams), typically is flying toward the plate at a speed of around 90 miles (144 kilometers) per hour. As the batter swings to meet it, his bat is moving even faster — about 110 miles (177 kilometers) per hour, in the opposite direction. In that 0.7 milliseconds in which the two meet, the ball is subjected to an average force of more than 4,000 pounds (1,870 kilograms) and a peak of more than twice that [source: Russell] . No wonder a video close-up of a ball striking a bat shows the ball being noticeably deformed, like the face of a boxer being punched. The bat deforms a little, too, flexing and compressing in response to the violent collision [source: Russell].

The result: The ball sails off into space—and if the batter gets his wish, into the cheap seats. But whether he trots across home plate in exultation, or walks back to the dugout in frustration after his harmless fly ball is caught, depends on a variety of factors. One important variable is whether he connects with the bat's so-called sweet spot — actually, a zone between roughly 4.5 and 6.5 inches (11.4 and 16.5 centimeters) from the end of the bat, in which the bat vibrates the least and transfers the most energy to the ball [source: Coburn].

Assuming that the batter accomplishes that, other variables come into play. How far a ball goes depends upon how quickly it sails off the bat, a measure that physicists call batted ball speed, or BBS, which is influenced by the bat's weight, but more so by the speed of the batter's swing. Against a 94-mile-per-hour (151-kilometer-per-hour) fastball, every mile-per-hour increase in bat speed adds 8 feet (2.4 meters) to the distance [source: Coburn].

Retired University of Arizona engineering professor Terry Bahill has found that the ideal bat for most major league hitters is in the 31-to-32-ounce (878 to 907 gram) range — about 20 ounces (566 grams) lighter than the hefty 54-ounce (1.5 kilogram) bat once used by Babe Ruth, the game's first great power hitter [sources: Coburn, Taube and Malta, Dewey]. Today's players need lighter bats to hit the greater variety of pitches thrown.

Baseball bats are made of either wood or aluminum. You'll see aluminum bats in youth leagues or in casual backyard games but Major League Baseball only allows bats made of wood. Aluminum bats are lighter than wooden ones, don't break and allow players to hit the ball farther and faster. Players in the major leagues are expected to have so much speed and power that they don't need the extra help.

Major League Baseball allows bats made out of one of six different types of wood: white ash, sugar maple, true hickory, yellow birch, red oak and Japanese ash. The vast majority of bats are made of either white ash or sugar maple [source: Roberts].

To make a classic Louisville Slugger, start with a white ash tree that is at least 50 years old. The wood used comes from special forests in New York and Pennsylvania. After harvest, the wood dries for six to eight months to a certain moisture level [source: Exploratorium].

The wood is then milled into round 37-inch (94-centimeter) cylinders called billets. When they arrive at the factory, they are put on a tracer lathe using a metal template that is set to the specifications of the baseball player. The Louisville Slugger logo is fire-branded on the flat of the wood's grain where the bat is weakest. A player must swing with the label up or down so he can hit the ball with the edge of the wood's grain which lessens the chance of the bat breaking. The bats are then sanded and dipped in a varnish that gives them a protective coat [source: Exploratorium].

Though the wooden bat seems more All-American, about 95 percent of the bats used in the U.S. are made of aluminum [source: Cole and Lundin].To make an aluminum bat, start with a simple aluminum tube 24 to 35 inches (61 to 89 centimeters) long and 2 to 3 inches (5 to 7.6 centimeters) in diameter. The tube goes through a process designed to thin, stretch and taper the tube walls and also create a handle. Then the tube is then treated with very high heat to remove lubricants and form grains to make it a harder material. At this point it looks like a bat but the ends of the tube are still open. Another machine spins the tube at high heat while a tool forces the softened ends to close over [source: Cole and Lundin].

Finally, the bat is polished and silkscreened with graphics and a knob is welded on to the handle. A grip, either rubber or wrap, is applied to the handle, and a label and a protective film are applied to the bat itself [source: Cole and Lundin].

Whether you're a sandlot ballplayer, or a parent shopping for a 10-year-old who dreams of being the next Miguel Cabrera, it's important to pick the right bat. Thanks to technological advances, there are all sorts of new choices available, and it's easier to find a bat that is tailored to the individual attributes of the player. It's important to take factors such as body type, height, weight, skill level and strength into account and to check league rules, to make sure a bat will be allowed in competition. Other factors to keep in mind:

Even with all that in mind, the best thing to do is to try an assortment of different bats until you find one that feels right to you.