[ayeckley]

Is this with the bot on the ground, or supported on blocks? If there is no load on the drivetrain then this seems pretty normal. We've been able to attribute this to backlash and the accompanying rattle within the drivetrain. With a "real" load the measurement should be more well-behaved since the masses are 10x-100x larger and the backlash-induced rattle goes away. Overdamping of the measurement (by cranking up the number of averages) brings it's own set of problems.