So I searched on the net and I'm having some problems imagining how the gimbal-lock occurs. According to what i saw, it occurs when 2 or more axes align losing a degree of freedom but I can't imagine how will the axes even begin to align?
I mean, when i rotate an object around x-axis (for example) doesn't the y and z axes rotate with the X-axis to remain perpendicular? How are they gonna align? Similarly whenever i rotate around Y or Z axis the other 2 axis rotate together and remain perpendicular don't they?
To get a more clear view what I am having problem imagining, check this video. At 5:05 https://youtu.be/Mm8tzzfy1Uw?t=305
You'll see when he rotates around the X axis the green and the blue rings remain there where as according to my imagination the green (Y) and blue (Z) axes should have rotated. I don't understand why the rings are still aligned with the world axis?