Using Divide Causes Extra Lines

[spiderartist]

Sometimes when I use the Divide function on a drawing, it creates extra lines by connecting open end points into different shapes.  I am an advanced user, so I'm careful NOT to have Fill on the lines.  Plus, it doesn't always malfunction like this. Curiously enough, when I create a new file and paste the drawing into a layer, it likewise makes the extra lines, but on another layer if I draw something new, the Divide function performs properly.  The original file remains corrupted when I open it on another computer.  Can anyone solve this mystery?

Here is a before & after of the result.  Also attached is the corrupted file.

[Monika Gause]

There is no attached AI file.

Also: why don't you spare yourself the need to make these "spikes" and use shapebuilder resp. Live paint?

[spiderartist · Accepted solution]

See my previous reply..

Here's a link to the corrupted file if you're interested in finding out why the Divide command didn't work:

http://spiderjohnson.com/Issues/

Also, I re-created the drawing in a new file, and the Divide command worked fine.  What a mystery...

[spiderartist]

Also:  I created an Action that gets rid of the "spikes" with a single keystroke.

[Monika Gause · Accepted solution]

There is a similar thread about this exact issue that has the solution to why this is happening: the fill rule.

https://community.adobe.com/t5/illustrator/extra-lines-being-created-with-pathfinder-divide-tool/m-p...