Union Errors in AutoCAD

Please read the following carefully before you make any comments. Thanks.

I have been trying to create a truss system for a model using AutoCAD. I had finally gotten the entire thing done only to realize that the diameter of the pieces were incorrect. I have since restarted the truss with the correct diameter. There are three errors that I have come up with in this process:

  1. Inconsistent face-body relationship
  2. Inconsistent edge-face relationship
  3. AG curve something

I have tried adding a sphere to the end of the cylinder to attach it to a corner, but this failed. I checked to make sure that the corner was completely solid, which it is. I then decided to check whether both parts were valid solids. The cylinder is, however the large piece that I’m trying to attach it to is not.

The questions I have are:

  1. Have you come across these errors? (Especially the third.)
  2. How do you suggest I remedy the issues?
  3. Would be it better to build a truss out of square rods instead of round?


P.S.-I’ve tried to attach the latest copy of the file, but I can’t save it as anything but a bitmap which is too large. I’ll try again from home.

What version of Autocad are you using? Some newer versions allow this, while some old ones, you have to trick the software to do what you want.

The school’s computers have AutoCAD 2002 installed.

I just saw your post. From what you describe, it sounds like you are working in 3D. When using the UNION command, some of the objects must intersect. In 3D it is difficult to see this sometimes. When drawing in 3D I use an oblique view (from the view toolbar) i.e. above right oblique. This give you a beter idea of where objects lie in the drawing. They may look like they overlap in your view but in reality are several drawings units apart. It is also helpful to have several UCS positions saved. When drawing or modifying objects that may require a rotation, I set a new UCS on the end point of one of the objects. Hope this helps.

Well, I am always changing my views to whatever I need it to be so that I can get a clear idea of where stuff belongs. And, if I make a mistake, I always undo it and recheck the orientations.

In addition, I was using “osnap” with only the endpoints set. Therefore, I know that my cylinders were starting and ending at the same point.

The solution that I found, using a top view, was to slice off the part that was going past the half way point of the spherical joint and then perform a union. I’m not sure, but I believe that the portion that extend past the half way point was creating a problem by being both inside and outside of the joint thereby giving the program difficulties in determining which section should be considered the outside.