Issues with Decimate modifier

[Culver_Dow]

Tried using the Decimate modifier on my pin, but, well

I am getting a lot of tris on one side of the pin. Super confused, because the rest of the pin just has flat polygons with 4 sides. This is with about 3 steps on the Decimate. Going any higher doesn’t show any change.

[gioele]

I had the same issue.
I solved it by remaking the pin from the point when you have to spin, but selecting a power of 2 in the “step” section (2 4 8 16 32 ecc).
also remember to remove doubles.