Hello gents, I just swapped blades on my X500. I thought for sure that the blade would be keyed meaning it would only fit onto the spindle one way but I did not see any key. Am I missing something? I installed the new blades and tightened to 50 foot lbs. Other than the force of the bolt, what prevents the blade from spinning on the spindle itself? There is a cup type device between the spindle and the blade but that seems to be just a dust cover to prevent dust from getting into the spindles.