Hi Johann

It depends on the position of the endifector and the object. J5 creates a bottleneck at some positions, but this can be overcome in some situations.

When the arm is fully extended, the maximum payload is often limited by the joint farthest from the base (in this case, J5) due to leverage effects. If the arm is positioned with the end effector facing downwards, or if it is curled, the load is more evenly distributed, with a significant portion supported by J3, where the upgrade is beneficial. However, to achieve a consistent lifting capacity in all positions, you will need to upgrade J5 from a nema 17 to a nema 23 and make a new motor bracket, and if J4 rotation is important while holding a heavy object, you will need to upgrade that motor too