Animating Model with Rotation About Single Axis

I am currently using assimp to import various parts of a robot model but would like to animate/skin it in my OpenGL environment to simulate a range of motion.
To my understanding, this isn’t really supported in OpenGL especially since I am dealing with .obj files.
I was curious if there was an implementation to support joints that rotate about one axis/point in my model.

For reference a majority of my code follows this series:
assimp loading - https://www.youtube.com/watch?v=yQx_pMsYqzU&index=29&list=PLRtjMdoYXLf6zUMDJVRZYV-6g6n62vet8
github repository - https://github.com/SonarSystems/Modern-OpenGL-Tutorials

I’ve also attached an image of a single joint in my model for visuals. Basically these parts interlock and should rotate within each other
Any help or direction would be appreciated!

Edit: My current attempt to implement this comes from http://ogldev.atspace.co.uk/www/tutorial38/tutorial38.html however to my understanding the tutorial assumes you have a mesh that is already boned in some way whereas my .obj is missing this information which lead me to think I should implement my own vertex/bone struct in my code.

Screenshot%20from%202018-07-27%2016-14-19