I am designing an articulated robot arm that will not need to hold essentially any weight at its end, but that will need to perform thousands of repetitions (currently using MG 996R servos, but might switch if those aren't durable enough). I am a design newbie, and as I've designed it currently, the only point of contact between each joint is the servo axle, meaning the weight of the arm is resting on that servo axle at each joint. I know this will produce undue stress on the axles over time, and I want to design the arm in such a way that the weight of the arm will not be placed on the servo axles. Can anyone point me in the right direction on how I can avoid that? Perhaps examples or principles of how joints can be designed such that the weight of the arm parts below it go through the frame of the arm rather than through the axle. Thanks!
This is commonly done by putting a bearing or two on the axis of servo rotation and making those bearing support the load. Try looking at parts like the Lynxmotion Aluminum "C" Servo Brackets. You can also look at products made by Trossen Robotics to see how they do it. And, search thingiverse.com for "servo joint", you'll see lots of ideas there.
Best of luck!