The woodworker's plane has barely changed since Roman Pompeii
The oldest known woodworking planes come from Pompeii, and a carpenter today would recognise them at once: a body with a slot through the middle, a blade angled down to its sole, and a wooden wedge tapped in to hold everything tight. Two thousand years later, many hand planes still work on exactly that principle.
A hand plane shaves wood using nothing but muscle. The blade, called the iron, pokes just below the flat bottom, or sole, and peels off a thin shaving on each pass. The clever part is the sole itself. Riding on the high spots of a rough board, it lets the blade trim only those peaks, so after several passes the surface ends up flat and smooth. Planes are used to flatten boards, bring them to thickness and smooth them, and specialised ones cut joints and decorative mouldings. Most are pushed away from the body, but Japanese planes are pulled toward the user.
Roman planes have also been dug up in Britain and Germany, and medieval drawings from Europe and Asia show similar wedge-held designs. The big modern change came in the mid-1860s, when Leonard Bailey began making planes with cast-iron bodies. Stanley Rule and Level bought his patents, and the Bailey pattern, refined by Justus Traut and others, became the template for most metal planes made today; Stanley Black and Decker still produces it.
Bailey also left a numbering system that other makers adopted. Numbers rise with length: a No. 1 is only a little over five inches long, a typical smoothing plane is a No. 4 at around nine inches, a jack plane is a No. 5, and the longest jointer planes are No. 7 or No. 8. Woodworkers typically flatten a rough board with progressively longer and finer planes, starting with a coarse scrub plane and finishing with a smoother, while the one-handed block plane handles end grain and small jobs.
Specialist planes fill a whole toolbox. The shoulder plane trims right up to an edge for joinery, the compass plane flexes a steel sole to shape curves, and tiny finger planes help violin makers carve instruments. Power arrived early too: in 1918 an air-driven planer spinning at up to 15,000 rpm let one shipyard worker do the planing of fifteen.
Source: Plane (tool)
