Ball joint

I use this with different arms and parts, for instance for supporting my webcam (see the 2nd photo).

Printing

No supports needed:

• balls: orient them so that the threaded part is onto the plate (the interior of the female part is a 45 deg cone)

Seam: random

This model has additional parts, a larger bolt, and the FreeCAD model.

The contact surface between the ball and the bolt is larger and will not lead to tearing layers apart, see CAD screenshot: the direction of the efforts being normal to the contact surface, the efforts flow almost along the extrusion lines, instead of perpendicular as with the original model. 

This change allowed me to increase a bit the max angle of the joint.

I reduced the diameter of the screw from M10 to M8, for the female/bolt part to pass through the knob bolt.