# Problem with Bevel modifier

I just started to learn Blender and met a problem when using Bevel modifier when creating a cogwheel. Most edges where processed fine, but a few of them got errors:

I have checked all the normals, they are correct. Here is the model without the modifier:

It seems ok, but I worry about black color of the edge exactly where the bevel makes mistakes

• Removed doubles? – 4-K Jun 5 '18 at 16:54
• Would it be possible for you to upload the blend file so we can take a look? – Prime_Aqasix Jun 5 '18 at 22:16

Thanks to hint from 4-K, I indeed found out that the problem was because of duplicates. To check it, I just moved single vertices in edit mode.

To remove them I did the following:

1. Open the edit mode for vertices.

2. Select all the vertices using A key.

3. Open special menu using W key.

4. Click "Remove Doubles".

Then Blender said that there were 8 redundant vertices, and I got correctly working bevel modifier.