Another nice thing about this is that the support bearing is external, away from the material being lifted.  Also, the drive motor can be anywhere along it's length instead of just top or bottom.,(reply>), @victor hopper huh?,(reply>), except there would be friction on both sides of the tube unless you double walled it with the outside wall not turning.,(reply>), Good point.  A tube is more robust than a spindly shaft.