Boolean Difference creates bad surface

After doing a boolean difference on my polysurface, the result is a damaged surface on the bottom “lip”.

Am i using wrong metod?


seems to be a simple render mesh problem. You can see that the isocurves flowing right, which hints that its rather a display issue.
You can try to increase the render mesh quality in your Rhino settings, better however is to simplify the shape. Usually such errors occur on “heavy” surface data (data with many and dense-placed control points).