X Arm Tip Idler Roller
The far-end block for the 'NEMA17 Cantilever Pen Plotter' kit's X arm, about 54 x 57 x 74 mm. It clamps the ends of two 8 mm rods set 40 mm apart in 25 mm pinch sockets (M3x16 screw plus a captured M3 nut in each). Two cheeks hold a 608 bearing as the GT2 belt idler on an 8x25 mm dowel, locked by an M3x10 self-tap screw. Below, a fork carries a 624 bearing on an M4x20 axle in a height-adjustable slot, so the arm tip rolls on the desk and can be levelled. It prints upside down, standing on the flat tops of the cheeks and clamps.
robotics kit pen-plotter 608-bearing