ORIGINAL: Bigpapascout
you can disagree all you want still dont change the fact that third axis leveling is to keep the windage in the same plane as the string when the sight is moved up or down it has NOTHING to do with up hill or down hill shots.
I'm going to have to go with everyone else and completely disagree with this statement.
In a perfect situation, with no torque etc., the 3rd axis adjustment would set your pins square to the plane of the string. That way the bubble will stay centered as the bow is tilted up or down. However, since each of us may grip or torque the bow differently to some degree it may not be set exactly square. That's why instructions on 3rd axis leveling such as those put out by Spot Hogg have you check those adjustments with your bow at full draw.
For the sake of discussion, lets take that perfect scenario where the pins would be square to the string. If the 3rd axis is not properly set and the pins are no longer square to the string, the bubble level can still be adjusted to be perfectly centered on level shots. However, tilt that bow up or down (as in an uphill or downhill shot) and now the bubble is going to float to the higher side. That side will be higher because the level (and your pins) are not square to the bow. Setting the 3rd axis properly will eliminate this problem.
It may be a little hard to understand, but try this example sometime. Take a level and hold an end in each hand. Now hold it out in front of you and get the bubble centered. Now lean back or forward, keeping your arms straight out in front of your chest. The bubble should stay centered. This represents the level on your sight when the 3rd axis is adjusted properly.
Now, pull your left arm in toward your body while leaving the right arm extended. When standing upright, you can still get the level centered in the bubble with no problem. But now when you lean back or forard, one side of the level is going to be higher than the other and the bubble will follow.