Are two arcs of equal radius truly parallels?
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They will be parallel in the very specialized sense of a constant offset in the Y direction at any X location. But if I do a “parallel contour” in a CAD program, the circles would be concentric…
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I think not technically. Only appear so within the small 33 inch span I’m dealing with.
Thanks Tod! The Join Vectors command is what did the trick. Now the tool path cuts as one continuous trip around the outside perimeter and not four separate cuts. Much appreciated. I’ll remember that.
Another option for this specific case (arcs cut by parallel line segments) would be to draw a rectangle the size of the workpiece (33 x 2.5) and use the boolean operator (selecting the rectangle and both circles) once the two circles are in place.
Why not just use the same center for both and decrease the radius of the inner circle?
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Because that’s not the way he described it. That likely would have been my first approach. 
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I found that aspect of the wording confusing and ambiguous.
Another option would be to just draw one circle of a suitable diameter:
Then move it:
Draw a rectangle:
Select everything:
Trim Vectors
remove what is not wanted:
OK
Draw another, wider 1" high rectangle:
Select it and the original:
Trim Vectors
Remove what is not wanted:
until one arrives at:
OK
OK
Select only the two horizontal lines:
delete
duplicate the arc and drag into registration:
drag the original into registration:
Select everything:
Join Vectors
Yes
Checking the nodes (see post below) we get:
I believe if the Smoothing algorithm worked as it should, 3rd degree continuity, you should be able to create a polyline or curve through these three points, select the middle point & hit “S” for smooth & get very close to a true arc. i.e. the ‘smoothest’ curve you can get through 3 points is an arc.!
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8 posts were split to a new topic: Arcs and Curves and Polylines
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