Plain bearing in the context of Lathe (metal)

A spear-thrower, spear-throwing lever, or atlatl (pronounced /ˈætlætəl/ or /ˈɑːtlɑːtəl/; Nahuatl ahtlatl Nahuatl pronunciation: [ˈaʔt͡ɬat͡ɬ]) is a tool that uses leverage to achieve greater velocity in dart or javelin throwing, and includes a bearing surface that allows the user to store energy during the throw.

It may consist of a shaft with a cup or a spur at the end that supports and propels the butt of the spear. It's usually about as long as the user's arm or forearm. The user holds the spear-thrower in one hand, gripping near the end farthest from the cup. The user puts the butt end of the spear, or dart, in the cup, or grabs the spur with the end of the spear. The spear is much longer than the thrower. The user holds the thrower at the grip end, with the spear resting on the thrower and the butt end of the spear resting in the thrower's cup. The user can hold the spear, with the index and thumb, with the same hand as the thrower, with the other fingers. The user reaches back with the spear pointed at the target. Then they make an overhand throwing motion with the thrower while letting go of the spear with the fingers.

A spear-thrower, spear-throwing lever, or atlatl (pronounced /ˈætlætəl/ or /ˈɑːtlɑːtəl/; Nahuatl ahtlatl Nahuatl pronunciation: [ˈaʔt͡ɬat͡ɬ]) is a tool that uses leverage to achieve greater velocity in dart or javelin throwing, and includes a bearing surface that allows the user to store energy during the throw.

It may consist of a shaft with a cup or a spur at the end that supports and propels the butt of the spear. It is usually about as long as the user's arm or forearm. The user holds the spear-thrower in one hand, gripping near the end farthest from the cup. The user puts the butt end of the spear, or dart, in the cup, or grabs the spur with the end of the spear. The spear is much longer than the thrower. The user holds the thrower at the grip end, with the spear resting on the thrower and the butt end of the spear resting in the thrower's cup. The user can hold the spear, with the index and thumb, with the same hand as the thrower, with the other fingers. The user reaches back with the spear pointed at the target. Then they make an overhand throwing motion with the thrower while letting go of the spear with the fingers.

A way (sometimes known as a slideway, guideway, or bedway) is a type of linear bearing, specifically a linear plain bearing, in a machine tool. It facilitates precise linear motion along a given axis. A way is ground, scraped, or (less often) molded to be very flat, and ways often come in pairs to ensure a flat plane for the carriage or sliding element (slide) to move along smoothly. Ways are usually lubricated with way oil (a kind of machine oil specially made to adhere to the ways while vertical).

Ways have been used since the 19th century and are a critical part of manufacturing processes, especially those requiring high tolerances such as machining. They have been made of various materials over the years, ranging from wood to cast iron, and nowadays including plastic alloys and special polymer materials. They are crafted with painstaking precision, usually being scraped into near total flatness with hand tools. This flatness is required to both provide good results in the manufactured parts, as well as prevent the stick-slip phenomenon (jerking motion due to friction at low speeds). In recent years they have started to be phased out by rolling-element bearings ("ball" bearings), or are forgone entirely in some CNC machines.