Planer (metalworking)

The most common applications of planers and shapers are linear-toolpath ones, such as: Although the archetypal toolpath of a planer is linear, helical cutting can be accomplished by coupling the table's linear motion to simultaneous rotation.

Additional uses include any other task where an abnormally large (usually in the range of 4'×8' or more) block of metal must be squared when a (quite massive) horizontal grinder or floor mill is unavailable, too expensive, or otherwise impractical in a given situation.

This principle easily explains why "old-fashioned" techniques often have a long period of gradual obsolescence in industrial contexts, rather than a sharp drop-off of prevalence such as is seen in mass-consumer technology fashions.

[2] In the late 1810s, a variety of pioneers in various British shops (including James Fox, George Rennie, Matthew Murray, Joseph Clement, and Richard Roberts) developed the planer into what we today would call a machine tool.

The exact details have been contentious and will probably never be known, because the development work being done in various shops was undocumented for various reasons (partially because of proprietary secrecy, and also simply because no one was taking down records for posterity).