How to Cut a 3D Polyline in AutoCAD Using the BREAK Command

To cut a 3D polyline in AutoCAD, you can use the BREAK command. This command allows you to either split the polyline into two separate entities at a specific point or remove a segment of the polyline between two specified points.

Here's how you can cut or break a 3D polyline using the BREAK command, incorporating the steps from the reference:

The primary method for cutting or splitting a 3D polyline in AutoCAD is by using the BREAK command. Depending on how you use it, you can either split the polyline at a single point or remove a portion of it.

Method 1: Splitting a 3D Polyline into Two (Cutting at a Point)

This method splits the polyline into two distinct entities at a single specified point without removing any part. This is often what users mean by "cutting" a polyline.

Steps:

1. Start the BREAK command: Type BREAK in the command line and press Enter.
2. Select the object: Select the 3D polyline you wish to cut.
3. Specify the first break point: At the prompt Select second break point (or F for First), type F and press Enter. This activates the "First point" option, allowing you to explicitly define the first break point.
4. Define the cut point: Specify the exact point on the 3D polyline where you want to make the cut.
5. Specify the second break point: Specify the same point again as the second break point. Picking the same point twice tells AutoCAD to break the polyline at that single location without removing a segment.

After completing these steps, your original 3D polyline will be replaced by two separate 3D polyline entities meeting at the point you specified.

Method 2: Breaking a 3D Polyline by Removing a Segment

This method removes a section of the 3D polyline between two points you specify. The remaining two parts of the polyline become separate entities. The provided reference steps align closely with this method.

Steps based on reference:

1. Select a polyline to break: Pick the 3D polyline at the point to be broken. This first pick selects the object and serves as the first break point by default (unless you use the 'F' option as in Method 1).
2. Select second break point (or F for First): Pick another point on the 3D polyline. This second pick defines the end of the segment to be removed. The portion of the polyline between the point picked in Step 1 and this point is removed.
3. Select a polyline to break: Press Enter. (This step, as provided in the reference, likely confirms the operation or allows selecting another object to break, though specifying the second point usually completes the command for a single object).

Using these steps removes the section of the polyline between the two points you selected, leaving the two remaining sections as separate polylines.

Key Considerations

• The BREAK command works on various objects, including Lines, Arcs, Circles, Polylines, Xlines, Rays, and other curves.
• For Circles, the break points determine the start and end points of the resulting Arc, and the break is always in a counterclockwise direction from the first point to the second.
• For Polylines, the points must lie on the polyline itself.

Choosing between Method 1 and Method 2 depends on whether you want to split the polyline at a point or remove a segment. Both are variations of using the BREAK command effectively.