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Offset ellipse

Contacting a toroidal cutter (not shown) against an edge (cyan line), is equivalent to dropping down a cylindrical cutter (lower edge shown as yellow circle) against a cylinder (yellow tube) around the edge, with a radius equal to the tube-radius of the original toroidal cutter.

The plane of the tip of the cylindrical cutter slices through the yellow tube and produces an ellipse (inner green and red points). The way this example was rotated it isĀ  obvious where the center of the ellipse along the Y-coordinate (along the green arrow) should lie. But the X-coordinate (along the red arrow) is unknown. One way of finding out is to realise that the center of the original toroidal cutter (white point) must lie on an offset-ellipse (outer green/red points). Once the X and Y coordinates are known it is fairly straightforward to find out the cutter-contact point between the cylindrical cutter and the tube, and from that the cutter-contact point between the toroid and the edge. Finally from that the cutter-location can be found.

Something to implement in opencamlib soon...

One Comment

  1. lode wrote:

    nice and clear visualization ...

    Friday, March 26, 2010 at 15:23 | Permalink

One Trackback/Pingback

  1. anderswallin.net › Toroidal drop-cutter on Wednesday, September 28, 2011 at 19:58

    [...] (red-points) are a bit more involved, and are done with the offset-ellipse solver presented earlier here(the initial geometry) and here(offset-ellipse construction) and here(convergence of the solver) and [...]

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