Checking a Plane Angle – in SketchUp?
Sometimes it’s easier to determine a difficult angle by drawing a model of the problem in SketchUp and measuring the angle.
Recently in one of my classes, while hand planing the surface of a drawer front, a student asked why I was “skewing” the plane as it traveled in the direction of the grain. That is, the plane was not aligned with the plank of wood, rather held at an angle to the direction of travel.
I was not accurate, nor complete in my answer, so I checked a reference, “The Hand Plane Book” by Garrett Hack. He explains that you get good performance with reduced cutting force by skewing the plane. In further explanation, Garrett points out that “…. the effective cutting angle is lowered” when skewing the plane.
Why does the angle lower, and how much lower? were immediate questions in my mind. So I quickly created a model of the plane blade in SketchUp, to compare the straight angle with the skewed angle.
Here is my resulting illustration (in Layout) showing the angle effect of skewing:
As shown, the effective cutting angle is reduced to 31 degrees when skewed at an angle of 45 degrees. This is a reduction of about 15 degrees, which is significant.
I realized that skewing may have the advantage of requiring less force, however the reduced angle can increase tear-out in difficult wood grain situations.