DXF sketches are not closed, but they are clearly closed before importing

[traditional.builds]

I make my sketches in Adobe Illustrator, then I send them to AutoCad, then into Fusion 360. This is my workflow because I have done my tests sending directly from Adobe Illustrator and it never works correctly, unfortunately. Regardless of my workflow, I am wondering WHY my sketches are not closed, and HOW can I check to see where the supposed "opening" is?

screenshot: hovering the extrude opperation over the shape that should be closed, but Fusion 360 tells me it is not.

Before exporting from Adobe Illustrator, I make sure that everything is the same color black, I expand and merge all the black and then convert the shapes to outlines. I then delete all the negative space left behind from the merge, so ALL I am left with is lines that are clearly closed. There's really no way that there could be an opening when doing this method. It's how I create vectors and I am very familiar with how Illustrator operates. My frustration is whenever certain sketches are inserted into a Fusion 360 plane the shapes are seemingly open. I say "certain" sketches because this seems to happen every other time. Sometimes they work and sometimes they don't. What is even more confusing is that sometimes if I m having an issue, I can simply re-save the file, and there is a chance of it working. It seems to happen on some of the more complex designs, which I can understand there being more room for error, but this has become increasingly frustrating. 

I have read and been told by a couple forum members that this could just be a bug/error in the way Adobe Illustrator/AutoCad/Fusion 360 read files slightly different, but it's strange that they work sometimes and other times they don't.

If in fact this is just  strange bug and I have to deal with it, how can I check where the apparent OPENING is once the sketch is in Fusion 360? It is easy to check in Illustrator, and I make sure to check, which is why this is confusing me.

I don't mind editing/altering the sketch a bit inside Fusion, but I am not familiar with how to "check for openings". Is this something I can check? I would love to find the root of this issue.

Thank you for your time in reading this. This will be a huge help for me,

Mike

*I will attach all the files I am using:
     - DXF file

     - DWG file

     - Fusion 360 file

     - screenshots

(I can also attach the Adobe Illustrator file upon request)

[HughesTooling · Accepted solution]

In this case it's not a gap but a bad spline that's causing the problem.

Tiny loops like this will make the profile detection fail. I've drawn a few lines across the area with the problem to help find the problem.

[HughesTooling · Accepted solution]

Double checked in Rhino3d and the same error is there so not a Fusion problem. 

[HughesTooling · Accepted solution]

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@traditional.builds wrote:

If in fact this is just  strange bug and I have to deal with it, how can I check where the apparent OPENING is once the sketch is in Fusion 360? It is easy to check in Illustrator, and I make sure to check, which is why this is confusing me.

I don't mind editing/altering the sketch a bit inside Fusion, but I am not familiar with how to "check for openings". Is this something I can check? I would love to find the root of this issue.

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One quick test is double click a curve will chain select all joined curves so can help find breaks. If there's only on small break this might not help as it will look like the whole curve is selected. So next draw some lines across the area with the problem like this then mouse over to find the problem area.

There is also a sketch checker here on the app store that finds open ends.

Mark

[etfrench · Accepted solution]

The Divide and Conquer method (dividing the area by drawing lines across it) works well for this as @HughesTooling shows.  When there are multiple levels of closed boundaries temporarily turning a segment into a construction line will help. 

[traditional.builds]

Thank you so much for the detailed response along with the screenshots. I completely understand what the issue was now that you showed me. I can easily alter the lines in Illustrator. I do not know how I didn't see that. This happens quite frequently with the sketches I import, so I just wanted to ask the forum.

Very much appreciated,

Mike

[traditional.builds]

Thanks a ton for the video capture. This was also super helpful and I see the issue. I will probably make the edits I need in Illustrator now that I see them. I made sure to double check the lines, but I guess I didn't zoom in as much as I should have to pick out those weird line connections.

Very helpful; I appreciate all the help,

Mike