Robust lead screw and thrust collar for InMoov bicep

thingiverse

To resolve frequent shear failures of the InMoov robot's bicep lead screw, a more robust plastic alternative was designed, increasing its diameter to 25.5 mm and enlarging the thrust collar accordingly. The pitch and length remained unchanged. To accommodate the bigger lead screw in RotGear, the hole for the thrust collar axis on the high arm side part was raised by 11.5 mm, achieved through plugging the old hole and locating a new one above it. For an optimal fit between the lead screw and thrust collar, apply petroleum jelly and work it back and forth several times. This ensures smooth operation with minimal torque required. A demonstration of this process can be found at http://haptictelepresence.blogspot.com/2013/03/seating-new-larger-leadscrew-in-bicep.html.