Spirals

Ideal Tools has a regular email they send out to subscribers (sign up through their website), which includes specials, and often some background info about what they are up to etc.

***Update*** you can sign up for the Ideal Tools Newsletter here

This time, they were talking about an ideal (heh) thicknesser they have just purchased for their training workshop – the Powermatic, with a Shelix head (a respected brand of spiral cutters).  They included a really cool graphic that I had to steal and use here.

Pity it is so small – it is hypnotic! (I want one (a Shelix head for my planer and thicknessers that is)!!)

As you can see from this closeup (also taken from the Ideal Tools email), not only are the cutters arranged in spirals, but they are also rotated so the edges of the cutters follow the spiral as well.  This is critical.  If the cutters are straight onto the direction of travel of the timber, they are chipping, not slicing, and no matter how much of a spiral they are in, the result is not the intent, or the finish that can be achieved.

The Shelix head does understand this principle.  The cutters will be a slicing action, resulting in very little tearout, even on cranky wood, and irrespective of grain direction.

But mostly, I just wanted to post that animation!