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Hello,
I am trying to draw a path on a topographical surface in AutoCAD. The path is 25mm above a number of topographical points, meaning the levels along the path are all different. I have successfully managed to draw in one side of the path using straight lines and Arcs drawn in different UCS's to allow me to draw an Arc at different points in the Z axis.
To complete the path I need to draw the other side 1800mm parallel to the line I have created. To do this I am using the Offset tool. Sadly, when I do this the lines don't seem to be copying exactly parallel as points are not joining up when I offset the different Arcs that are in the path (see below images).
I am only getting this error for the arcs that have been drawn. The straight lines in the path are fine.
Does anyone know what is going wrong here? Any help would be appreciated.
@Anonymous wrote:
.... I have ... one side of the path using straight lines and Arcs drawn in different UCS's to allow me to draw an Arc at different points in the Z axis. ....
That is why it doesn't come out as you are hoping. An Arc can be Offset only within the plane it defines, so if they're in different planes, even if they meet at a common end, the results of Offsetting will not meet. Here's an exaggerated example:
The yellow Arc is on the XY plane, and the red one in a vertical plane. The red and yellow solid Arcs meet at the crossing of the blue Lines. But since their Offsets [the dotted ones] can't be in other than the planes of their source Arcs, obviously their ends can't meet. The differences in planes in your drawing will be much smaller than this difference, but there must still be a [similarly smaller, but not zero] difference in endpoints of the Offset results.
I don't know of a way around that, except to then adjust them as you did in the other thread.
Kent Cooper, AIA 
Hi,
Thank you for getting back to me.
I did think this was the case so this was something i had tried.
I have tried this again just to make sure I am not getting the same issue and these are the results I have found.
I defined a new UCS by setting a point on the X axis for my arc (I am 99% sure this is correct as the original points that are not offset align perfectly).
Once the UCS has been defined I have selected the Offset tool and set the offsetting distance to 1800mm.
When I offset the arc the lines do not cross anywhere on the Z axis.
I then looked at the offset lines in birds eye view which shows that they do cross as some point on the X axis.
I am slightly confused as to how this is possible? If the original lines did not line up along the Z axis I would understand. However, as these lines are meant to be a parallel copy i'm baffled as to how these offsetted copies cannot link along the Z axis?
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