Since altair did not post his drawing (and since he is new to 3d) I have no idea what result he actually got but here's something interesting:

When I do what he describes (which has the same result as Prl's drawing, but minus the planes), if you measure the final angle in the XY plane (from the original vertical position)it is 30 degrees. However, if you measure the angle from the 2nd position (after the 1st rotation) to the final position, the angle is 28.152 degrees (well, Prl's drawing says 28.5)... ~~even though the 2 endpoints of the 2 angles line up in the YZ plane (ie, if you look at the 2 arcs from the front 2d view they will start and end at the same XY coordinates)~~ ...even though, when viewing from the front 2d view the arcs appear to end in the same line. This would lead into thinking they are the same angle, when they are not.

If in 3d you draw 2 arcs to describe these angles and rotate the 28.152 one -20 degrees on the X axis, so it ~~lays~~ *starts* in the same plane as the 30 degree arc, you will see why this happens: ~~the 2 arcs do not have the same radius~~ ...arc-2 does not *end* in the same plane as arc-1, but is actually twisted forward.

Therefor when rotating with the XYZ system you have to keep in mind what plane your rotation angle relates to. If altair wanted his cylinder's 2nd rotation to be 30 degrees in the tilted plane he would have to maybe change the working plane to match the plane of the cylinder (I say maybe because I'm sure there's another way to achieve this**) and then do the 30 degree rotation in the Z axis (and then reset the working plane, of course).

Also, the final result of a series of XYZ rotations differ depending on which axis is rotated first, 2nd and third. To get a consistent result regardless of the order of the rotations you would have to use the HPB system (heading, pitch, bank)... well at least according to Cinema4D. Their manual goes to great length to explain this but it lost me completely (testing their words in both systems prove them right, however). This is important in animation systems so the results are the same every time.

Lar

** now I remember: use 'rotate about a line' (if, like me, you would group a center line with the cylinder) or 'about 2 points' (if, like me, you have sticky handles on and you keep the automatic handles you can snap on handles 0 and 1).