Wheel Axle Bridge
A 16 x 36 x 11.5 mm black box-section axle bridge from the 'SG90 Wheeled Serpentine Snake Robot' kit. It bolts under each Servo Segment Housing floor with two M3x12 SHCS through 3.4 mm holes into the floor's M3 heat-set inserts. Each flat outer cheek at y = ±18 carries an 11 mm M4 heat-set boss with a 5.5 mm teardrop bore. That bore takes an M4x16 SHCS as the axle for a 624-bearing tread wheel. A bottom tie and a centre web stiffen the cheeks against wheel side-load, and relief pockets let a hex key reach the M3 screw heads.
robotics kit snake-robot 624-bearing