Hello, why this edge has a defect of curvature about edge? At smaller radius there is no problem…
Untitled.3dm (1.2 MB)
Nothing to look at or attached.
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It is possible to face such problem at any geometry…
By the way, the zebra also sees this defect.
I have created a usual square, (G2), Extrude has smoothed things over. At different radiuses strange results… And how to explain it?
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Though it is possible to adhere to a good corner when smoothing edge - then free of defects. 
