head spins. The cutter head's axis of rotation is parallel to the table surfaces and perpendicular to the feed direction. The knives cut into the board in the direction opposite to the feed.

Modern jointer models may contain a spiral, or helical, cutting head. This configuration has many individually mounted, self-indexing knives with 4 sharp sides, that can be rotated to a new edge when necessary. Rarely, older models have cutter heads that are not cylindrical but instead square. This leaves a significantly larger open region below the