Sorvall centrifuge and rotor: I screwed up! - (Jun/19/2006 )

So I have had another failed experiment. This time, something that was supposed to be pelleted didn't get pelleted after centrifugation.
I think I did everything right, except *possibly* one thing. You know, when you use the big centrifuge (Sorvall), the rotor has two screws that you have to tighten. I'm usually very careful about these things, but this time I *might* have forgotten to tighten the smaller (inner) screw.

My theory is that because I forgot to tighten the screw, the rotor didn't reach the desired speed (even though the indicator panel was displaying the correct rpm value), and it didn't produce enough 'g' forces to pellet this material (cell nuclei to be specific). Does this sound reasonable to you?
I guess my question is, what do you think happens when you fail to tighten the screw on the rotor?

I'm actually hoping that was what happend. Otherwise, I'm completely lost in this experiment!

even if you initially experience some slippage the rotor will still attain the set speed. the inner screw is to ensure that the rotor doesn't 'take off' if it becomes unbalanced.

it is unlikely that this is the cause of your lost pellet. sorry.

Thank you for your comment.
I discovered that when the inner screw was not tightened, I could lift the rotor a little bit by hands, and that's the reason why I got the impression that the rotor might not be fixed well to the spinning part of the centrifuge under this condition. But you seem to be an experienced person so I beleive you.
I don't know what was wrong then. Oh well.