The Spiralling Tool wheel (shown to the right) is sharpened by rubbing a 120 - 150 grit diamond file against the bevel on the wheel whist it is being spun. The surface to be sharpened is indicated by the arrow.
The wheel can be spun by hand, or by pressing it against a spinning piece of scrap wood.
The Texturing Tool wheel (shown to the left) should be spun by pressing it against a spinning piece of scrap wood.
This is highly recommended as the edges are pretty sharp points !