Helical Cutter Head vs Spiral Cutter Head

There is some confusion surrounding helical and spiral cutterheads for wood jointers and planers. While both terms are synonyms and refer to a form of winding around a center or pole, the grooves along which the cutters are placed on the cutterheads differ.There are two common types of cutterheads. Some folks call the top one (Fig. 1) a spiral cutter and the bottom one (Fig. 2) a helical cutterhead, while others use the opposite terms. This makes it confusing to claim that a helical cutterhead is superior to a spiral cutterhead.

We distinguish the spiral cutterhead on top and the helical cutterhead on the bottom. Spiral cutterheads utilize carbide inserts with round edges at varying radii, such as R150 and R100, with the most common size being 15x15x2.5mm (as shown in Fig. 3). The inserts are angled to the board's feeding direction, allowing for a shear-cut.
In contrast, helical cutterheads use straight-edged carbide inserts that are square (90°) to the feeding direction. Popular sizes for this type of cutterhead include 14x14x2mm or 15x15x2.5mm. The helical cutterhead directly cuts materials without a shear cut, whereas woodworkers are aware of the numerous benefits of the shear cut. It's important to note that the carbide inserts are not compatible with each other.