Shading Issues with the Array Modifier I'm working on a model of a car wheel. However, before I continue, I want to fix some shading issues I am having.

My model has Subdivision surface, Mirror, and Array modifiers, which make up the 10 spokes/"slices" of the wheel. The wheel itself is all one, contiguous object. However, there are multiple areas where the shading looks a bit odd.

Problem #1: Seams at the End of Array

While my Array modifier has Merge Vertices checked and all angle values were precisely calculated/typed in to ensure that all of the vertices in the circle line up, the very last seam where the last segment connects with the first does not merge.





I think that this is because the Array modifier merges vertices only with each next part. Even turning on Automerge editing to merge vertices that are close enough globally does not work, because of the Array being a modifier and not applied. I have tested applying this modifier, and the problems did go away. However, I wish to keep it in an array and was wondering if anyone has any other solutions.

Problem #2: Hard Edges on Circle

At the center of the wheel, where all of the spokes converge, there is a circular edge which appears to not be affected by the Subdivision surface modifier. 





No, it is not marked a hard edge -- it is completely parallel with the two lines in front and behind it too, but those are completely curved as normal.

Problem #3: Artifacts at all Array Seams

In the indicated center part of the model, there is a shading artifact. It happens where each part of the array has a seam. 



Does anyone have any advice? It would be best if you could download the .blend file to mess with it:



But either way, I'm happy to have any feedback on the best way to fix these various artifacts from those more experienced than me. Thank you so much!
For the first issue, you just need to 'merge first last' in the array modifier. This option tells Blender that the extremities of the array have to be merged.



For the second one, it is because the flat face normal is inverted. Select your mesh and use ShiftN to recalculate the normals.



An easy way to check if normals are inverted is to turn on x-ray:



The third one is because the wheel border is not 'regular'. To make it more regular, use the knife tool K to make a loop along the wheel border.

That will make a ngon (on the face above) but luckily that doesn't matter here. Eventually, turn it to quad+tri (not shown in the gif below).