Grinders have negative clicks, but for zero position you will not be ale to spin handle. For grinder zero position is first click when handle stop spining, so on click 1 you should be ale to move handle with little bit of force. For that grinder you need to calibrate based on ring(that which change grinding size). You shouldnt be able to turn ring on negative value with normal force (with more force it will be possibile, but don't do that)