"Cannot offset that object.". No reason given why not. (2014)

[Anonymous]

The worst part of this stupid bug that has existed for nearly 3 years, is that it shows me the location of the offset line, where it would be, but then just fails to create it.

Only solution I've found is to redraw the line. Which obviously only works if AutoCAD feels like making it work.

The Knowledge Centre recommends flattening the polyline. I've tried that. I've tried exploding it then re-joining it then offsetting it, no dice. I've tried offsetting it half the amount, with the intention of offsetting the created line again. Of course that doesn't work, that would be sensible.

The polyline has 12 vertices.

This thread has the same problem from 2012 and no-one managed to fix it (how to make the overkill command work is not stated, and it didn't work for me).

I know redrawing the line would have taken less time than creating this thread, and that's what I've been doing up until now. This must be the 20th time I've encountered this stupid bug.

Any ideas greatly appreciated

EDIT: Should mention the workaround i've always used is to copy the polyline into a new drawing, and then offset it, then copy it back. Yes I'm serious.

[dbroad]

Post a copy of the drawing with only the problem polyline.  Otherwise, we'll be just playing 20 questions.  Also, if you believe its a valid defect, put a support request in to Autodesk.

[pendean]

Are you sure it was a LINE object? LIST command would have told you what it is.
If it was a PLINE (with 12 vertices) it may be the offset distance/direction you chose is just not possible. But a PLINE is not a LINE, so which is it?

As noted above, post the DWG file, point to this "line", explain in detail how we are to replicate your problem please.

[Patchy]

Probably was drawn as 3dpoly, like this example.

[rkmcswain]

dbroad wrote:

Post a copy of the drawing with only the problem polyline.  Otherwise, we'll be just playing 20 questions.

Yes OP -- please do this!

Otherwise we are wasting everyone's time guessing.

[Kent1Cooper]

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@Patchy wrote:

Probably was drawn as 3dpoly....

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That possibility occurred to me, too, except that the workaround described in the EDIT at the end of Post 1 would not work in that case.

[Patchy]

Maybe the in newer versions it converts the heavy to lightweight polyline when copied.

I'm using only 2008, I'll try it later on different PC.

[Anonymous]

It's a PLINE, with 12 vertices, but I just call plylines lines as they're the only lines I use now, as they're bteer than the line command in nearly every way IMO.

I'll post a drawing when i can replicate the effect next. Autocad is currently playing ball

[Anonymous]

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@Patchy wrote:

Probably was drawn as 3dpoly, like this example.

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your example replicates the problem quite well, but is that the only way to convert a 3D polyline to a 2D polyline?

Try using the FLATTEN command on your 3D polyline: it doesn't work for me. Isn't that the exact purpose of the flatten tool: to make it 2D, thus make offset work??

So if I'm right: is the only solution to copy the faulty line, explode it, join it again, then try again?

[Patchy]

Try different PLINETYPE setting and use CONVERT command on those "Lines"

[Anonymous]

Just tried replicating the bug by drawing the exact same polyline using the exact same technique, and I offset the line and of course it offsetted completely fine!

Still trying to replicate the issue, I know computers aren't truly random but AutoCAD is much more random than I can humanly perceive when it wants to be.

[Kent1Cooper]

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cam01096 wrote:

.... 

Try using the FLATTEN command on your 3D polyline: it doesn't work for me. Isn't that the exact purpose of the flatten tool: to make it 2D, thus make offset work??

....

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When you say "it doesn't work," do you mean that it doesn't put the 3DPolyline flat in the XY plane, or that it doesn't make it into something that you can use Offset on?  FLATTEN only makes things 2D by forcing everything onto the XY plane.  It does not [is not intended to] change the entity type of a 3DPolyline to convert it to a LW or 2D "heavy" one -- if that is needed for some reason such as to be able to Offset it, that would need to be a different operation.

[Anonymous]

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@Patchy wrote:

Try different PLINETYPE setting and use CONVERT command on those "Lines"

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They are, and always have been, polylines.

Anyway at long last I've been able to partially replicate either the existing problem or a new one.

When the line (which means "polyline") in the existing drawing is offset by 5, it appears as in the attached screenshot: with a massive hole in it. How do I close the gap in the original line to stop it doing this? I've just used the FILLET command to recity it until now, where the command wouldn't close the gap as the line ends are parallel, not perpendicular.

This isn't the same as the original bug but i think it's caused by the same thing: something in the original drawing breaking it. but here the line stands alone, no other layers (except one that refused to be binned), etc.

The FLATTEN command doesn't work here, but the line is not a 3d polyline according to the properties window.

[Anonymous]

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@Kent1Cooper wrote:

FLATTEN only makes things 2D by forcing everything onto the XY plane.  It does not [is not intended to] change the entity type of a 3DPolyline to convert it to a LW or 2D "heavy" one -- if that is needed for some reason such as to be able to Offset it, that would need to be a different operation.

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Does such an operation exist? Is it the CONVERT command? Because if you try that on the drawing I have attached in my above post, neither does it make the line 2d (command line says "0 2d polyline objects converted" when I try).

How do I convert a polyline to a 2d polyline?? And would that even fix the problem?

[Kent1Cooper]

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@Patchy wrote:

Maybe the in newer versions it converts the heavy to lightweight polyline when copied. ....

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If the PLINETYPE System Variable is set to 2, it will convert "heavy" 2D Polylines that are just line and arc segments [e.g. not spline-curved, etc.] to LW Polylines on opening the drawing containing them, but that has no relation to 3D Polylines, if they are the source of the trouble.  "Heavy" 2D Polylines can already be Offset anyway, so that kind of conversion-to-LW through going into a different drawing would not be needed.  Something else must be going on....

[Patchy]

You can fix it, get autolisp (Kent surely can do it with ease) but you can go here and get the program:

http://cadtips.cadalyst.com/3d-editing/convert-3d-polylines-2d-polylines

[Kent1Cooper]

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@Anonymous wrote:

....

When the line (which means "polyline") in the existing drawing is offset by 5, it appears as in the attached screenshot: with a massive hole in it. How do I close the gap in the original line to stop it doing this? ....

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The 3D vs. "heavy" 2D vs. LW issue and FLATTEN question are moot given the LWPolyline in the example drawing.  That Polyline looks closed but is not, in the meaning of the term in AutoCAD.  Its start and end vertices are merely at the same place.  Closing it by picking Yes in the "Closed" slot in the Properties box makes it closed but doesn't fix the problem, probably because of the resulting 0-length segment at the start/end location.  I think what you want to do is to get it to be closed in the "normal" way, that is, with only one vertex at that start/end location.  There are routines on this Forum to make apparently-closed Polylines be truly closed, such as this one that asks you to pick one, and this other one that does it to all open Polylines in the drawing but can be adjusted to let the User select multiple objects.

And when drawing things like this, be sure to make the closing segment by using the Close option in PLINE, not by picking a last vertex back at the starting vertex location.

[Anonymous]

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@Patchy wrote:

You can fix it, get autolisp (Kent surely can do it with ease) but you can go here and get the program:

http://cadtips.cadalyst.com/3d-editing/convert-3d-polylines-2d-polylines

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Cheers for the lisp, I tried it on the test file I uploaded earlier though and it didn't convert the line as it said it wasn't 3d to begin with.

In properties, the line also says it's not closed but changing the "closed?" dropdown menu fron "No" to "Yes" doesn't actually close it either. Good ol AutoCAD...

[Patchy]

We have 2 different topics here; 3dpoly cannot offset then we fix it with the autolisp. Your uploaded drawing isn't it.

Yes, it's very strange you LWPOLYLINE is closed, I can stretch that corner with grip, check ID with high precision and it gapped when offset.

Fillet zero distance and move on I guess.

[Anonymous]

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@Patchy wrote:

We have 2 different topics here; 3dpoly cannot offset then we fix it with the autolisp. Your uploaded drawing isn't it.

Yes, it's very strange you LWPOLYLINE is closed, I can stretch that corner with grip, check ID with high precision and it gapped when offset.

Fillet zero distance and move on I guess.

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You're right, although I thought they were related. Back on topic then:

The error came up again. I have a polyline that cannot be offset, please find it in the attached drawing.

This is the problem that comes up intermittently, and I'm not sure what causes it. Using the 3d-2d polyline lisp on it didn't work as apparently it's not a 3d polyline.

Cheers for the help, glad I finally got the problem isolated!