From: Eidolon Aeon
I don't know if this is relevant: I'm rotating multi-prim objects.
It's not strictly relevant to the question as asked, but still, there is an important thing to know about rotating linked objects. Linksets have not one, but two pivot points. When you rotate the object via the on-screen manipulator (hold ctrl to turn the manipulator from move mode to rotate mode), the pivot point is the object's geometric center. But when you type numbers into the editor, the pivot point is the center of the parent prim. This can seem a little confusing at first, but it's actually a very important, highly useful, feature.
From: Eidolon Aeon
One thing that's been driving me crazy is that the values in x, y, and z seem to be arbitrarily changing. I'll type in a value for one axis, and one or both of the other axes switch values. Is there some math going on here that is over my head?
What happens is the editor constantly reworks the numbers to come up with the simplest set of values required to achieve the current rotation. For example, if you type 450 into any field, it will come out to 90, since there's no need to rotate one and a quarter times when just the quarter will do the job. When you're working with all three dimensions at once, the ordering of the number choices can get complicated, and I don't fully understand exactly how it comes up with the choices it does. I've always assumed the recalculations are they system's way of avoiding gimbal lock, but I don't know that for sure.
All that really matters is that in the end, the actual orientation of the object comes out the way it should, even if the numbers aren't entirely what you had wanted them to be.
Sometimes it can be a little frustrating if you're trying to rotate incrementally by changing the numbers just a little bit at a time. In cases like that, then it's best to do what Lee suggested, which is to use the manipulator to get as close as possible, and then fine tune with the numbers if necessary. And if the dual pivot points are a problem, don't be afraid to link the object temporarily to another prim, in order to place the numerical pivot wherever you want it to be.
Also, make use of the on-screen rulers. When you're rotating an object, the ruler becomes a protractor. You can snap your rotation to the degree marks by dragging the mouse onto the protractor as you're rotating the object.
Generally speaking, you'll find that rotating via the manipulator rather than by the numbers is the easier way to work. I use the numbers pretty rarely, myself, for rotation.
Oh, and here's one tip which I'm sure you'll find highly useful. Reference mode is fantastic for rotation, especially with complicated objects. If you happen to know the numerical value you want, but you're having trouble achieving it with the entire linkset due to the pivot being offset from the center, the reference ruler can be a life saver. Simply rez a single prim, assign the rotation to that, then reference it (select it and press shift-G). The rulers (including the protractor) will then realign themselves to match the orientation of the referenced prim. From there, just snap your object to the referenced cardinal directions, and it will be perfectly aligned.
I hope that helps.
