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Extend options in r14

© Jonathan Jonas

A funny thing happened the other day at the office... really, I was at the office, and I was finally getting really annoyed with AutoCAD 14. You see, like most people who have been using AutoCAD since the begining of time, I stopped reading the command prompts. I tell students to always read it, and I explain to them how AutoCAD uses this area to tell you important little pieces of information about what you are doing. Unfortunately, as a grandfather of CAD, I forgot this basic step myself and was quite content with having the majority of responses memorized. Well, when I started using r14, I was surprised by how AutoCAD would seem to go all buggy on the Trim and Extend commands occasionally. I talked to various users and got a mixture of responses from "I hate it when it does that" to "I've never seen that happen". I figured I found a bug / feature of ACAD and let it go at that. Finally today I was sitting there and I glanced down at the command prompt and actually bothered to read what it said.

Here's what it said:

Command: ex EXTEND

Select boundary edges: (Projmode = UCS, Edgemode = No extend)

Select objects:

/Project/Edge/Undo:

Now, thinking I've never seen this Projmode or Edgemode before, I think to myself that this might be the reason why I'm having trouble with ACAD. So I look at the Trim command also.

Here's what it said:

Command: trim

Select cutting edges: (Projmode = UCS, Edgemode = No extend)

Select objects:

/Project/Edge/Undo:

Imagine my surprise when I saw that there too. Quickly I went to look up these two new commands in the help section. I found under the Projmode two entried; PROJMODE System Variable (ACR) and Trimming and Extending in 3D (AUG), as well as EDGEMODE in the AutoCAD Command Reference.

So, I think, maybe this will clear up the problems I have when I try to use Extend or Trim. On some drawings the Extend would let me select a line and then I could extend to it another line in its path the way it is supposed to. However, if I used the trick of pressing [RETURN] when it asked me to select objects, thereby selecting all objects in the display as objects to extend to rather than extending to the first object in it's path, it would instead stop every couple of inches along the way. Quickly this would become tiresome. What the problem is is that Edgemode was set to 1 rather than 0. This variable will allow you to change whether the first line directly in the path of the extending line is extended to (Edgemode 0) or if it will stop at all apparent intersections (Edgemode 1). Edgemode 1 will also allow you to extend a line in 3D space.

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