Upper Arm Elbow Link
This is the shoulder-to-elbow link of the 'SG90 Four-Axis Desktop Robot Arm' kit. It is a 5 mm flat bar, 22 mm wide, 80 mm between axes and 119 mm long overall. The Ø24 × 9 mm shoulder hub has a double-arm SG90 horn pocket on the bottom face (7.5 × 36 × 1.8 mm, Ø5.3 screw hole) and a Ø16.05 × 5 mm press-fit pocket on top for a 625 bearing (5 × 16 × 5), with a 2.2 mm web between them. The elbow end has a 28 × 12.6 mm SG90 window with M2 ear slots, which puts the elbow servo shaft at 80 mm.
robotics kit sg90 robot-arm