Dear Blender Stack Exchange Community,

After trying to model a sword (after a concept art) I did run into some issues after using the Knife Project Tool. I am trying to add some Screws using the Extrude, Subdivide Command and Proportional Editing. However, after applying the Knife Project, weird Shadings started appearing.

I fixed the middle indent by connecting it to the rest of the geometry. The screw holes were done by keeping the produced geometry (Knife Project) selected and applying the transformation once, for all of them.

Now I did ask myself, whether I'd have to manually connect my screw holes to the rest of the mesh,or whether there is another, smarter way. Because by using this method I lose the accessibility of using efficient and clean loop cuts. I certainly do want to avoid ngons and poles as much as possible.

By the way, never mind my weird Subdivisions in the screw hole, I was going to fix it after solving this Problem.

Weird Shading

  • $\begingroup$ This is very simplistic but when I cop shading problems/streaks after modifying a straight forward topology, I get into Edit mode and simply ease vertices in and out/above&below. That often cures the shading problems or at least alleviates them. $\endgroup$
    – Edgel3D
    Commented Feb 20, 2017 at 1:24
  • $\begingroup$ Shading in this case will surely be corrupted as you have very nasty Ngons forming surface around the holes. Make those holes with lower amount of vertices, like 8, and use insetting to avoid changing curvature (and hence shading) on the sharp edges. $\endgroup$
    – Mr Zak
    Commented May 4, 2017 at 20:51
  • $\begingroup$ Yes. Certain tools (booleans, knife, knife project) will do that. If you want to use those tools, be prepared to retopo. What's the question? $\endgroup$
    – Nathan
    Commented Jul 5, 2018 at 21:19

1 Answer 1


I have had the same problem with shading after using the knife / knife project tool. Unfortunately, I believe there is no sure-fire way to fix this. One way that may work is to slightly bevel all the edges. Another is to set the shading of the faces to flat, and leave the shading of the others at smooth.


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