3d DXF Export - Arcs not not connected to other lines and arcs

Hi all, I’m having a bit of an issue exporting DXF files, they seemingly export fine, but when I zoom on Autodesk Viewer all individual arc and line end points miss each other, some are unmeasurable on the viewer though some are as far apart as 0.5mm

My file is made up of only lines no faces, I set the camera to Parallel Projection and Top view and export using the 3D DXF export option with only lines selected (though have tried some other options too to no avail). Both the SU file and DXF are attached bellow, any help with this would be very much appreciated as I’m trying to get the files to over to my CNC shop ASAP.

CNC_Sheet_1.dxf (127.0 KB)
CNC_Sheet_1.skp (147.5 KB)

Do you see the same thing with this one?
CNC_Sheet_1.dxf (919.0 KB)

No, in this one everything seems to be connected, but it has segmented all the arcs instead of creating true radii.

Also just for reference this is what I’m seeing on the exported DXF

What timezone are you?
Dave will be asleep by now and you may have to wait a few hours for the usual .dxf/.dwg suspects to wake up and have their coffee.
I have little experience with CAD files.
One thing I will note about your .skp, it does have some faces but I doubt that is the issue.

Yeah I had noticed those faces, I had accidentally created them when fixing some other geometry. I’m in Australia so probably a bit out on timing haha, I think I have missed the boat to get these files cut this week so I do have Friday and the weekend to work things out now, but cheers for letting me know.

It looks to me that the lines stay the same length as they are when joined to a segmented arc and can’t adjust to meet the true position of the arc endpoint when converted?

That explains it, everyone else is either going to bed, in bed, or thinking about getting out of bed.

interesting. I get no gap between the arc and line segment, and can do pedit-join in autocad, resulting in a connected poly line with arc inside the polyline. Could this be a version of the small segments problem? My export is hundred meters long.

This vid might help you out, and or point you to a fix.

Forget everything you know.

Just download the free plugin ABF Solution and you’ll get correct arcs, nesting, tags and more.

That is interesting, do you mean you exported the file at 100x scale? Not Ideal but could be a workaround…

Thanks, though I have already watched that one unfortunately in my hunt for a solution.

Thanks I’ll have to to give that plugin a try and let you know how it goes.

The gaps I find are in the circular elements that have a straight line cut into them. The reason, to me, seems to be that the line cuts the circle at a random point that lies on a segment, not at a vertex. The vertices are points on the real circle/arc but the segment lines form a polygon that is inscribed into the arc or circle. Now when you export to DWG, the line cutting a segment is no longer on the path of the true circle. If you want the two to meet, the meeting must be arranged at a vertex point.
Here, I redrew one of the shapes by copying the line and drawing the arc provocatively with 7 segments, from the ends of the line and with the same radius as your shapes:

Looking at a resulting DWG in Rhino , it is clean and can be jined to a closed shape:
The arcs can be corrected by changing their segment count in Entity info. That makes SketchUp redraw them with even-length segments

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When using the reflect tool, the sketchup redraws the geometry and using the tool 2 times, you have the same thing on the screen, but for Sketchup and AutoCAD it is a new geometry.

Thanks for the detailed reply @Anssi, that does fix some of the gaps in my file, though I am also still getting small gaps where I have added tangent arcs (and even deleted the resulting arc and retroactively drawn it again with the resulting line lengths) in the though that this might be the issue.

Each image is a further zoomed in version of the previous

I had originally assumed that for the purpose of exporting to things like DXF that Sketchup would retain metadata on the required line length needed for a true unsegmented arc when a line gets cropped by a tangent arc though it seems that this is not the case unfortunately.

I see that many people seem to be successfully exporting DXFs with curves and arcs and I cant believe that all of them are going though this same process? Our company is looking at doing more CNC work in the future and if this is what is needed to simply export a usable file then I think we might have to start thinking about alternative software.

That last one is odd. I cannot see it in the DXF you originally posted or the DWG I exported myself, viewing in DWG TrueView 2021, and when I edit it in Rhino the chain of lines and arcs combines neatly into a closed polyline.
What scale factor is your screen using?

Interesting, could I be possibly chasing a viewer issue? I’m using Autodesk online viewer as I’m on a mac and don’t have info on the scale factor. @Anssi if you’re saying the other chain of lines and arcs are combining on Rhino then I don’t have any more issues!!! I assumed that problem you highlighted earlier and the one I was seeing were related, though appears it is not a problem at all!

I’ll check my CNC guy doesn’t have any issues using the files and report back.

On that not does anyone have a reliable free software for macs I can use to check DXF exports before I send them?

Thanks for all the help guys, and thank you @Anssi, you have saved me a lot of hassle.

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