Question
What is the difference in performance, if any, between the spiral head and helical head I'm considering for my 8" jointer?
Forum Responses
(Solid Wood Machining Forum)
Sunhill sells both types and gives a lot of info. Then run the numbers for your usage. Pro or hobby? The spiral knives are HSS and the helical are carbide. Carbide can be rotated on four edges. Spiral are flexible steel one edge and disposable. Their tech can explain it in more detail for you. Regular knives are still a lot cheaper. Many folks have a hard time changing knives because they haven't been shown how properly. I can change regular knives on an 8" four knife head in about 15 minutes within .0005", but I work on machines for a living.
Both will perform well in soft woods, but the helical knives tend to leave very slight lines between the cutters which are easily sanded. The spiral will leave a nicer surface. Obviously, the carbide will last about ten times longer and can be rotated four times. HSS initially has a much sharper edge.
