Trim command skipping lines

[chrisjob]

Hi.

Not sure if someone will now this answer (or whether it's a know problem) - can't find the answer on any forums.

When I initiate the trim command with a double enter (i.e. select all mode), I usually first zoom into the area I want to trim so I see no other objects, then start the trim <Enter><Enter> option, then pick the lines I want to trim.  Even if these extend off the screen and cross other objects (not seen on the screen), they usually trim off completely.  However, on occassion they don't.  To replicate the problem try this:

1. Draw 2 vertical lines and 2 horizontal intersecting (like noughts and crosses)
2. Draw a horizontal line that intersects both vertical lines but up near the top of those lines
3. Zoom in so you only see the square and extending lines (but not the short horizontal line)
4. Trim <Enter> <Enter> and pick from bottom right to top left (i.e. around the square
5. Zoom out.

The square is trimmed, however there are 2 line fragments left above the horizontal short line.

Fix:

1. Undo
2. Trim the same way and presto, it now works

I found if I then moved the line above (so only a small amount), zoomed in again, tried to trim - same error.

Can someone help here?  Please screen shots attached.

[dmfrazier]

I was able to replicate your results (AutoCAD 2013), unless, at step 4, instead of using a crossing window (I assume that's what you meant by "pick from bottom right to top left") I select the lines I want trimmed individually.  In this case the upper line is ignored as a trim edge.  AutoCAD seems to be a little inconsistent with what constitutes "all".

[pendean]

As a test: zoom in, regen, then trim <enter> <enter> and see if your occasional issue goes away.

[braudpat]

Hello

Just a stupid question :

Are you FAR from X=Zero & Y=Zero ?

Bye, Pat

[chrisjob]

Sorry I wasn't clear. Yes it is with a crossing that I trim. On occasion I find that it is inconsistent and doesn't trim eac line as it should. I teach AutoCAD and this is a typical example I show students of a quick way to trim, but it doesn't always work. If I undo, and then repeat it works. If I regen it doesn't always work. If I move an object then trim, again that object affects the trim. Any ideas why?

[chrisjob]

Sorry I wasn't clear. Yes it is with a crossing that I trim. On occasion I find that it is inconsistent and doesn't trim eac line as it should. I teach AutoCAD and this is a typical example I show students of a quick way to trim, but it doesn't always work. If I undo, and then repeat it works. If I regen it doesn't always work. If I move an object then trim, again that object affects the trim. Any ideas why?
In answer to how close to x y origin, I found that had no positive or negative affect.

[doben]

I've noticed this too - I think it's a bug. It has happened many times so I end up just manually selecting the lines. 

Are you running Civil3D or another vertical? I'm not sure if I've had it happen in vanilla ACAD but for sure in C3D.

[chrisjob]

Yes, it does happen in vanilla AutoCAD.  I've found it has been happening for quite a while.

It funny because when you say "select all", AutoCAD usually only selects objects visible on the screen, however here it doesn't.  Yes, I think a bug.