FOR THE ANVIL - It's really frustrating because i see people with the exact same problems as me but i feel like I've tried everything. Recalculated normals. Merge by distance. Getting rid of ngons, and just none of it seems to work! I bet the problem is something simple, but I'm new to blender so I don't know what to do. The cube also shows up on only one side, which is odd.

FOR THE GUN - I bet it's something to do with the way I modeled it, but in object mode there's a weird black line streaking across the model where certain edges are, but I just can't fix it. This brings up another question I have though - are ngons and tris really that bad? I was under the impression it's awful to have ngons so while modeling this I was making sure there were none, but it just led to more problems. Knife cutting led to more ngons, more ngons led to more unnecessary loop cuts, etc. So, if you have an ngon or tri should you go through the effort of removing it? If so, what's the best way to go about it without accidentally creating even more? Anyways, I hope that was clear enough for someone to answer because I felt like I was spewing out sentences.



Links to both of the blend files I'm talking about, hope this works since I don't know how to upload blend files here.

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    $\begingroup$ Hello and welcome. For future reference it's better to ask a question for each problem. $\endgroup$ Jul 8, 2021 at 6:52
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    $\begingroup$ I think it is a good idea to just redo the tutorial from scratch in addition to fixing this. It's probably a little bit annoying to redo stuff, but it fixes issues like this and also helps you learn how to do it well. I am not really sure how to make geometry like that on purpose to be honest :D $\endgroup$ Jul 8, 2021 at 6:54
  • $\begingroup$ @MartynasŽiemys Right, strange isn't it? Like what I say in my answer on the anvil, there are faces doubled by using the same corner vertices... I don't know how to produce that from scratch, I could imagine if I import some weird geometry from a different program this might happen, but following a Blender tutorial...? Actually I would be interested in how this accident happened, this might help to make people aware of what could go wrong and maybe find better solutions to repair this mess. $\endgroup$ Jul 8, 2021 at 7:24
  • $\begingroup$ It would be really interesting to know how one makes double overlapping faces that share same vertices. :D All Blender operations I can think of take care of this and remove double faces automatically if vertices are the same if I understand this correctly. Looks impossible. It would really be interesting to know how this happened. I tried and could not repeat this. :D $\endgroup$ Jul 8, 2021 at 8:09
  • $\begingroup$ I think this is what happened to the person in this question! - blender.stackexchange.com/questions/226828/… I uploaded the blend file for this question, and I thought I had the same thing happening at one point, but I was evidently unable to reproduce it in the file I actually saved. Might be something to watch out for... @MartynasŽiemys $\endgroup$ Jul 8, 2021 at 17:25

2 Answers 2


For the anvil: I have no time to fix it for you right now, but when I activate the Overlay > Face Orientation it shows that a lot of face normals are pointing inwards (shown in red) instead of outwards (shown in blue) as they should be. Also, looking at the top of the anvil there are definitely faces overlapping because there are areas where red and blue are mixed. Also notice on the side, faces are not only flipped but also overlapping. You can see it especially where the red and blue colors in these areas are more saturated than in other areas. It looks like you have a lot of doubled geometry.


The problem with Merge etc. is that most of the model is double faces using the same vertices - I don't actually know how to create this, but what it means is if you click a quad face and delete it, there is another quad face in the same place. Merging vertices doesn't help because both faces are built of the same four vertices.

double faces

Even selecting Interior Faces doesn't select them all correctly, I don't know how to get rid of them or if there is any function in Blender to select them automatically. So if nobody comes up with a better answer this is all to be done manually, I'm afraid. Clicking a face to select it, hitting X to delete it. Maybe you can select more at once with Box Select or Circle Select in Solid View, so that only the top faces are selected. But if you delete some and there are no more faces beneath them left, it might be harder to fill the holes if there are corner vertices missing afterwards.

Once you have all double faces deleted, you can select all with A, then Shift+N > Recalculate Normals. Now they should all be shown in blue.


For the anvil, you have faces overlapping, and Merge by Distance doesn't seem to fix it. A quick way to fix it is to choose Face Select mode, select everything in the 3D view with the box or lasso without the X-Ray enabled so that it doesn't select the inner faces, invert the selection, delete, then don't forget to recalculate the normals.

For the gun, there's a line because the top face is separate from the bottom faces, if you move one of the vertices from the bottom faces you'll see that they are not part of the top face:

enter image description here

It's not a problem to have ngons or tris as long as it doesn't create artefacts

  • $\begingroup$ The only problem with the anvil and selecting everything without x-ray for him might be to identify where there are double faces, because they are not everywhere. And it is important that he only deletes faces, not edges or vertices, because only the faces are doubled, not the edges and vertices (howsoever he created that). $\endgroup$ Jul 8, 2021 at 7:32
  • $\begingroup$ i've edited to specify to use Face Select, and also just invert, which will allow to spot the double faces (even though it doesn't change anything) $\endgroup$
    – moonboots
    Jul 8, 2021 at 7:50
  • $\begingroup$ Yes, it helps a little, but still there's the problem that in some areas all faces get deleted... but it also depends from which angle I'm selecting the faces, it might work out if you're lucky :) $\endgroup$ Jul 8, 2021 at 8:01
  • $\begingroup$ I'm not sure to understand, it seems to work fine here... $\endgroup$
    – moonboots
    Jul 8, 2021 at 8:02
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    $\begingroup$ ok it must be the circle select that selects the overlapping faces then $\endgroup$
    – moonboots
    Jul 8, 2021 at 8:14

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