Hi Ken,

There are many influences on the plane that cause this. First off is the sharpness of the plane. If the edge is not truly sharp, the blade incrementally rises as the stroke is made and concludes with less shaving at the outstroke than at the instroke. This can also work in reverse. Another great and very common fault is what i call ‘bulldogging’ the plane down onto the wood instead of simply pushing the plane forward and letting the plane itself pull itself to the wood. Because of the angle the blade is set at, the iron pulls the plane down, so our task is not so much to press but to push. You must also check the flatness of the sole, the amount of blade protrusion and so on.