Cutting angles
Keith Tompkins
>John Lucas recently posted about cutting angles, or rather,how the tool is presented to the wood, affects the cut produced by the tool.
In the case of the skew, when the cutting edge is 90 degrees to the tool rest, the cut is directly into end grain, so the cut is more difficult. By "skewing" the cut to a 45 degree angle, wood fibers will be sheared or peeled away.
The same effect will be experienced in end grain hollowing....many turners have difficulty in turning end grain because they are attempting to cut straight into the end grain. A better solution would be to make a small starting cut into the center (I use a spindle or bowl gouge), then make a shearing cut from the center to the rim.....only the initial cut into the center was end grain! Just repeat the process to hollow.
Like John, I experiment with tool angles....for instance, a bowl gouge rolled until the flute is nearly straight up will give a very clean shearing cut.
For good beads and coves in spindle turning, the tool must be presented right on the center line on it's side, otherwise, the tool tends to thread itself along the turning.
I have found that the higher the skew is presented to a turning, the worse the catches will be. Why? When the tool catches, there is more wood under the tool, which then pulls the tool further into the catch. (Similar to the effect of hollowing with the tool on center, a catch pulls the cut deeper into the wood).
John, that was actually a great thought provoking post...I'm surprised it didn't get more response! You can't alway just go by what the book or video says....It's ok to experiment.
