Monday, February 04, 2008

Sharpening Wood Turning Tools (2)

As Derek was saying (see his site by the way at Seafoam Woodturning )The motions used in freehand sharpening are similar to those we use in turning. For instance, to sharpen a roughing gouge one

  1. presents the tool resting on the grinder table (that rest in front of the wheel) with the flute up and the tool not yet touching the wheel.

  2. if right handed the handle is held in the right hand against the right hip

  3. the left hand steadies the tool on the grinder table

  4. raises the handle until the heel of the bevel touches the wheel gently and a hair more until sparks move over the edge

  5. roll the tool to the right as sparks move over the edge

  6. roll the tool to the left as sparks move over the edge

In theory the tool has moved through the same motions as cleaning a fine shaving right and left. The sparks coming over the edge indicate that a sharp edge has been formed and you are ready to turn.

In reality I find this is the time turners move the tool in wide arcs as they inspect the edge for sharpness and for facets on the bevel. If you are unsure of your sharpening enough for this to happen, you will likely consider

  1. the edge not good enough

  2. too many facets on the bevel

  3. the angle has changed

and back to the grinder you go until you have really messed things up or give up in disgust and go to the work anyway and find the edge works fine, but could have been better.

One of the big problems is simply you moved before returning to the wheel. The practice is sound but it needs practice. Try a couple of things.

  1. practice the motions with the grinder off. Feel the bevel on the wheel and do it several times. So it takes a few minutes; hopefully you are going to do this for the rest of your life.

  2. ignore the facets. No one else will see them and they will not really affect the final cut no matter what the jig using people like me say.

  3. ignore the angle. You have not likely changed it enough to matter. A degree or so is not the damage most people think. If you are off five degrees or more you really need a coarser wheel to reshape it and that is another subject.

  4. most important of all, do not move your hands from their anchor as you look at the edge. The left stays on the tool shaft and the right on the handle at your hip. That way you become the jig and the tool returns to the same place each time

I hope this helps. More thoughts to come.

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