UCS stands for User Co-ordinate System, meaning user coordinate system (defined by the user).
This term has both meaning and command. UCS is related to WCS (World Co-ordinate System) normal coordinates (AutoCAD uses the word world as normal). If you observe the screen in every work, there will be a sign showing WCS at the bottom left corner of the screen called the WCS Icon as shown.
In the normal state, this icon indicates the 3 axes (axis) in working, namely X, Y and Z, which are arranged at right angles to each other according to Right Hand Rule 1 In the 3D view, the Z axis (blue) is perpendicular to the X, Y axes, meaning that the working plane is the plane that is parallel to XY only as shown.
Or the area shown in red If we want to work in the green or blue plane, we can’t. Because it is a plane that is not parallel to the XY plane (XY plane) because the program requires us to create work in a plane parallel to the XY plane only, so from the figure to create tasks on the green plane The XY plane must be rotated parallel to this green plane before any work can be created on this plane.
To rotate the working plane, use the command UCS to rotate the coordinates in the direction that we (User) want to adjust from the normal position when starting to work. Adjust coordinates from normal (world) to user (user) coordinates for 3D creation.
UCS commands are commands with several options and descriptions. Today I would like to use a convenient and comprehensive method. That is using the alternative UCS / 3-point tool as shown.
Once the order has been selected, set the 3 coordinates as shown in the figure.
By starting at point 1, the origin point, then going to point 2, the end of the X axis, and point 3, the end of the y axis. Then the working plane will change as shown.
Notice that the UCS Icon has an XY plane parallel to the desired (green) area. If a work piece is created, it will be on this plane. Try modeling and rotating the 3-point UCS to change the working plane in different ways to gain insight.
If you have a problem, ask any time in the comments.