Cleaning Up Objects So They Will Sweep or Extrude

Polylines that intersect or overlap themselves will not sweep or extrude in AutoCAD. Here are some ways to clean those bad objects up so they will function properly for you. June 8, 2008

I cannot sweep or extrude a self-intersecting curve. Any ideas what a self-intersecting curve looks like? I'm getting this message sometimes when I try to extrude objects with lots of curves and arcs.

Forum Responses
(CAD Forum)
From contributor A:
It means the profile of your sweep will intersect itself following your path and it cannot do the operation because of it.

From contributor B:
Chances are that the object you are trying to extrude has overlapping lines or arcs. Did you make this profile yourself or copy it from another drawing? Without seeing it and knowing exactly what you are dealing with here are a few things to try.

Check the properties and see if itís a closed polyline. Explode it and use the overkill command to get rid of any lines or arcs that might have been doubled during creation. Many times people are not as neat as they should be and they forget to clean up extra lines or objects when making things. After cleaning it up go through each point where two objects meet and use the fillet command to make sure they are connected. Remake the polyline. Double check it to make sure itís closed. Extrude it.

After I make a profile Iíll use the boundary command to make the closed polyline then use the move command and the last option to move the new profile over so I can use it. If the boundary cannot be made I know there is a problem, and then I go hunting.

From contributor C:

I usually get that when the profile I need to extrude has lines overlapping. Make sure you use one poly-line with no overlaps.

From contributor D:
As to the extrusion, you can also validate what you are trying to extrude or sweep by using the region command. If the shape can be turned into a region, then you can usually sweep it. If it won't turn into a region, it's because of the problems mentioned in the previous post. I'm pretty sure the region will sweep just like a shape.

From the original questioner:
I got a molding profile from an Architect's drawing. I exploded the block and then made sure there are no overlapping lines and no open ends. Also I did check for negative or positive "Z" s and I fillet all the corners. Then I used PEDIT command to make closed polyline. I made polyline but it was resisting to extrude, giving me a same message. I exploded pedit, generated polyline and using boundary command, made another closed polyline boundry, and it worked. To contributor A: You are right, but I'm extruding it on strait path, it should not intersect itself.

From contributor B:
Those architects will get you every time. Save yourself some time and make a custom button ^C^C-boundary. You will find lots of uses for it. Whenever I use a profile from someone elseís drawing thatís the first thing I do, then delete the original. Even when I make a profile from scratch I use the boundary button - itís faster than pedit, and lets me know if there are any open areas.

From the original questioner:
BO -> enter, works as well. I basically have no problems with any type of boundary I have drawn myself. Problems often happen when I have something pasted in from Architectural DWGs and in most cases those drawings are produced by people who maybe excellent Architects, but are terrible AutoCAD users. Anyway, thanks to everybody for responses.

From contributor A:
It seems that the profile itself had an overlap in it. This can occur when you use pedit to join lines and arcs in to one closed polyline. The command will add any extra lines needed to close it. Sometime they are on top of each other or a line so small that it always measures 0. If it was drawn properly you would not be having this issue. You can always explode it back to lines and arcs and then move each entity off to the side, end point to endpoint, and reconstruct it. After you put the last piece in you should then click on it to highlight the grips, click in the grip opposite to the endpoint you placed it with, and then move to the endpoint of the other line or arc that it is supposed to be connected to. It may be going past it just a hair. This is typical problem of using the trim command on arcs when moving too fast and failing to notice that the trim did not go all the way down.

From contributor E:
I used to have the same problem, but the thing is that sometimes AUTOCad extrude command just doesn't work with objects with too many curves and arcs (I don't know why). One of the solutions could be:
1. explode the object(s);
2. transform those objects (lines, arcs, etc.) to polylines (PEDIT>Multiple>(select all of the desired objects)>Confirm (YES);
3. JOIN converted polylines (PEDIT command).
Now extrude the object(s). It should work.

From contributor F:
I was having this problem. I googled it and what do you know, this thread came up. Fixed the problem.Thanks guys.