Planer, Plano miller is a type of metalworking machine tool that uses linear relative motion between the work piece and a single-point cutting tool to machine a linear tool path. Its cut is analogous to that of a lathe, except that it is (archetypally) linear instead of helical. (Adding axes of motion can yield helical tool paths) A planer is analogous to a shaper, but larger, and with the entire work piece moving on a table beneath the cutter, instead of the cutter riding a ram that moves above a stationary work piece. The table is moved back and forth on the bed beneath the cutting head either by mechanical means, such as a rack and pinion drive or a lead screw.

The most common applications of planers and shapers are linear-tool path ones, such as:
·  Generating accurate flat surfaces. (While not as precise as grinding, a planer can remove a tremendous amount of material in one pass with high accuracy.)
·  Cutting slots (such as keyways).