Reply by Richard H

The ridges are caused by the ends of the iron bitting into the wood (plane tracks). You need to put a slight camber on the iron or round over the ends so they don’t dig in. There are a lot of different ways to do this depending on how you are sharpening but the easiest is probably just putting more hand pressure on the outside of the iron when you are working it on stone/sandpaper/diamond. Once you have a camber on the iron use the adjuster to center the shaving and set the depth of cut so it tapers off at the two edges rather than creates a hard edge and you should see the grooves go away.

Hope this helps,

Richard