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Elllsworth to Wolverine jigs

Discussion in 'Tutorials and Tips' started by Jed Dyke, Aug 30, 2012.

  1. Bill Boehme

    Bill Boehme Administrator Staff Member

    Jan 27, 2005
    Dalworthington Gardens, TX
    Home Page:
    OK, I am sorry that I am not able to convey my message clearly enough. Perhaps if we get to meet sometime at a symposium I will be able to demonstrate in person.

    I do understand about the rotation point. The rod is 1/4" diameter with a hemispherical tip which means that the rotation point is actually 1/8" from the center of the tip. It is possible that the bottom of the Oneway Wolverine V pocket is too broadly curved to maintain the end of the Ellsworth jig at a reasonably fixed location. If so, the that would need to be addressed. The rotation of the Ellsworth jig would be about an axis described by a line from the point that I mentioned above to the midpoint of the bevel that is in contact with the wheel. The whole jig and gouge rotate about this centerline, but note that this is not a fixed line at the gouge end. The orientation with respect to vertical and horizontal are irrelevant.

    If one could construct a fixture that is free to rotate about the same axis as the motor shaft with a pivot point for the Ellsworth jig located at approximately 11.75" (give or take to get the proper 60° angle) from the center of that axis then it would not matter which orientation around the circle you chose to use. Another way to envision the same thing is to change the frame of reference from the workbench to a X and Y axes scribed on the wheel itself. From the perspective of the grinding wheel, it is stationary while the tool is racing around its perimeter.

    And, if we wanted to take a relativistic approach where somehow our bench, workshop, lathe, and everything else disappeared and we found ourselves out in empty space with only the grinding wheel, gouge, Ellsworth jig, and this mythical fixture that I described, then all that we could say is that there is relative motion between the wheel and the other components. We are free to establish our own coordinate system so if we were to locate ourselves on the wheel, we could create a fixed inertial frame of reference on it and then everything would be orbiting around the wheel. The converse would be true if the fixture was used as the reference frame. Another possibility is to use the gouge and jig as the reference frame in which case both the fixture and wheel could be moving as we worked the whole bevel of the tool.
    Last edited: Nov 2, 2012

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