Spiral will not cut a circle. Documentation incorrect.

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dgolber
Posts: 36
Joined: Wed Mar 26, 2014 7:22 pm

Spiral will not cut a circle. Documentation incorrect.

Post by dgolber »

Rhino 4.0 SR9
RhinoCAM 2012, 3.0.0.48

The Help file says about Spiral Machining that "It can be used efficiently for circular regions."

This is not true: Given a circular region, Spiral Machining will not cut a circle.

The reason seems to be the detailed statement of what Spiral Machining does. As far as I can see, the statement is this:

======
Assuming we are spiraling out from inside a region. Look at the path from above, and ignore the vertical motion. When the path hits the edge of the region,
(1) If there is more of the spiral inside the region, the path moves along the edge of the region until it hits the next part of the spiral within the region, and then moves along the spiral.
(2) If there is no more of the spiral inside the region, this is the end, and the tool retracts.
=======

The path does NOT make a last pass along the whole edge of the region.

So if the region is a circle, the path never passes along the full edge of the circle. The pocket that is cut is somewhat circular, but the edge of the pocket is actually one turn of a spiral ending in a part of the edge of the tool.

It would be nice if MecSoft gave us some description of what each machining operation _does_, like the above between the ==== lines.
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