Recommend a book or demonstrate how to specify angles and explain use 3DROTATE

[Karol-Or]

Is there a place (PDF book, kindle or site) to demonstrate the use of complicated commands like 3DROTATE? I select Y axis as the axis of rotation, why am i prompted to select a point on the Y axis? the axis is the same on all it's length. I am prompted to select the angle, i select 2 points perpendicular to Y axis and the object rotates 180 deg, not as i want What are the rules for angle selection?

[SEANT61]

Sadly, I think that command (Rotate3d) is somewhat lacking as a 3D command.  The ‘Reference’ sub option appears constrained to angle aligned with the XY plane.

This command macro helps with the acquisition of an oriented 3d angle:
^C^C_Select;\_rotate3d;previous;;\\'cal;ang(cur,cur,cur,cur);\\\\;

The screencast demos the macro in actions, whilst also showing the intention of the “Specify a point on the Y axis <0,0,0>:” request.

Screencast will be displayed here after you click Post.

[SEANT61]

Here is the aforementioned screencast.

[leeminardi]

I think the rotate3d command is more powerful and easier to use than 3drotate.  Try it!  In addition to being able to rotate about any of the principal axes of x, y, or z you can choose any two points for the axis.

Command: ROTATE3D
Current positive angle:  ANGDIR=counterclockwise  ANGBASE=0
Select objects: 1 found
Select objects:
Specify first point on axis or define axis by
[Object/Last/View/Xaxis/Yaxis/Zaxis/2points]: y Specify a point on the Y axis <0,0,0>:
Specify rotation angle or [Reference]: 30

You should also look into the align command for rotating objects in 3D.

[Karol-Or]

What is the cur command (not endpoint, nor midpoint etc.) in the macro?

It doesn't work in 2013. i copied it and pasted in the command line and error

[SEANT61]

Macros in general, and that one specifically, tend to employ syntax incompatible with 'Copy and Paste' direct to the command line.  It's intended to be inserted into the AutoCAD UI via the CUI command (see image).

The step by step procedure can be recreated via the Command Line with the proper interpretation of the symbols.  

If need be, I could record another screencast using standard command line entry to demonstrate the sequence, and similar results as demoed previously.

[Karol-Or]

Yes but what is the "cur" in: ang(cur,cur,cur,cur)

Are these endpoints of lines or what

[cadffm]

cur is your selected point / lastpoint..
For ang function:
Check the help-page of cal's ang function

https://help.autodesk.com/view/ACD/2018/ENU/?guid=GUID-155E4F77-9315-4F8E-B31E-FE75A807AD97

[SEANT61]

As explained by @cadffm, the cur function allows the use of any osnap.  If I just used end, then I would not be able to isolate an angle via an arc's cen, for example.

This page also has some info on cur:

https://help.autodesk.com/view/ACD/2018/ENU/?guid=GUID-E7D43A99-6518-490E-AEF6-B89164D02DF1