A cutterhead is a crucial component used in jointers, planers, and other woodworking machinery, and choosing the right one can significantly impact the efficiency and quality of your woodworking projects.

Cutterheads come in two popular types: spiral cutterheads and helical cutterheads. Regarding helical and spiral cutterheads for wood planers and jointers, there is a bit of confusion.

While both terms refer to a form of winding around the cylindrical shaft, the recessed grooves that the knives are positioned along on the cutterheads are different.

What are Helical and Spiral Cutterheads?

Spiral cutterheads consist of a cylindrical shaft with rows of small square indexable carbide inserts placed close together in a spiral pattern. These indexable inserts are made of carbide, and tungsten carbide is the second toughest substance in the world, so these hard tungsten insert knives possess a lengthy lifespan and require minimal maintenance.

Moreover, since the cutting action of carbide inserts is segmented across the whole cutter head diameter, as opposed to at two or three specific spots, they are also marginally quieter than straight knives.

Helical cutterheads, on the other hand, feature a row of square carbide insert knives around a cylindrical shaft in a helical pattern, each set on an angle following the helix. This structure provides a smoother wood surface than a traditional straight cutterhead.

Carbide inserts are better than straight knives because carbide insert generally has 4 cutting faces that can be individually indexed 90 degrees, so if you damage any knives or they get dull, you can always rotate the inserts to expose a fresh cutting edge. This also extends the service life of helical cutterheads.

In addition, one of the most important benefits of helical cutterheads is the reduction of tear-out through a shearing cut action. On challenging woods or high-density materials, helical cutterheads usually result in significantly smoother finishes. 

Application

Spiral cutterheads are primarily used for cutting softwood and low-density materials where the cutting forces are relatively low. The spiral orientation of the inserts allows for efficient chip evacuation, making them suitable for materials that generate a significant amount of waste during the cutting process.

In contrast, helical cutterheads find primary applications in cutting hardwood, high-density materials, and challenging-to-process materials. Carbide inserts on helical cutterheads are positioned at a slight angle, creating a shearing action that helps reduce tear-out and produces a smoother surface finish, even on difficult materials.

In short, compared to spiral cutterheads, helical cutterheads regularly produce smoother surface finishes and less tear-out, which makes them suitable for fine woodworking projects.