Certainty importing/exporting curves and circles using DXF files?

[Anonymous]

Hello,

i am new to AutoCAD, but comfortable with Adobe Illustrator which is of course also vector.

Lately i have two different vendors requesting/receiving DXF files from me for laser cutting quotes.

A few weeks ago "Vendor A" told me i had major scaling issues when i exported from AI as a DXF, so this is when i signed up for AutoCAD 2018 and used that to open my same DXF and re-save it and then give them that. Despite this seeming redundant, it seems to work since i haven't heard complaints from this vendor again. 

Totally different vendor, Vendor B, contacted me today tell me that my DXF file was showing all splined/jagged circles and curves. I had created their DXF in the same manner... from AI, then saved through CAD, and then to them. However, previously i had not done this for Vendor B. Previously i had sent them direct AI files. But, they're requesting DXF from here on since it's less work for them, but it's coming through as jagged edges.

I understand there are settings within AutoCAD that control how high of resolution the "display" of the document is.. but, is this really adjusting the total resolution of the file itself??? That seems shocking to me. 

What are the different options for setting curve resolutions, and which are "actual" changes to the design lines, and which are just for basic screen display? 

When i go to make adjustments to the document settings, i try everything and sometimes it doesn't appear to make any adjustments at all and then sometimes it will suddenly change after 5 minutes goes by. 

Can someone please help a newbie get acquainted with the fundamentals of curve integrity? I want perfect full curves. This is for laser cutting of my product, with screws holes all over the place. Cutting "nearly" perfect curves that look pretty good to the eye but don't allow a screw to go through would be an utter waste of prototyping time, ie. a couple months of my business clock.

thanks!!

[maxim_k]

Hi James,

As I understand, you create your drawings in AI, then export them to DXF. Am I correct?
If yes, then you need to adjust settings in AI, because the second step - opening document exported from AI in AutoCAD, then resaving it again - will not give you anything other than adding additional distortion to the geometry of the curves.
AutoCAD itself always produce correct smooth curves in the document regardless settings you make to screen curves resolution.

If you I am correct, and you create your drawings in AI - Can you share an example of the drawing (or part of it) here in AI format + the final result you get for Vendor B in DXF format? I'll look at it and will try to figure out the problem.

[Anonymous]

Thank you,

You are correct that i create my vector designs in AI. That is really all i need.

But because my vendor A raised an issue saying the scaling was dramatically off (by a factor of a few thousand percent), i decided to subscribe to AutoCAD 2018 in order to try saving it within there and send them that. I believe that worked, so something must be different from the AI export vs the AutoCAD file saved. Both DXF. 

One thing I'd like to point out is this.. when i export the DXF from AI, and open it in AutoCAD, it automatically displays as jagged lines in AutoCAD. This happened when i very first ever used AutoCAD a couple weeks ago. I simply downloaded the software and open the DXF and all of my curves had jagged lines. 

However, I had not made any adjustments to the export process from AI, and there really aren't many options either. This is AI 2018, completely up to date. 

Here are images of the Vendor B process, in order of the process. This is the vendor that is saying i have "splined/jagged" curves. Please continue to read downwards..

First is the drawing in AI. Perfect curves of course.

Then is the DXF export window, with the default settings. The scaling window is covered up, but it's just 1 to 1. My issue isn't scaling with this one.

After that is opening the DXF is AutoCAD 2018. You can see if you look closely that there are jagged edges. 

Then after that is a zoomed in close up of jagged edges.

Then last  is the window with adjustments for documents settings, which i have been trying to understand but sometimes i don't see any results whatsoever. However, I am assuming from what you said that these have no affect on the document itself as it's imported, exported, or saved. The only reason i ever tried making adjustments in that window is because AutoCAD, from the very first moment, made curves appear jagged. Again, i have never used AutoCAD and/or opened any documents ever before this. So it's confusing as to why the default settings for AutoCAD would be set so that curves were jagged. Additionally, i have made no other settings adjustments in AutoCAD. 

[pendean]

AI is not AutoCAD, if this is a critical shape/profile you need to send to AutoCAD users it is best if you create the content there instead. Use AI for sharing with AI users only, it is the best solution.

If you wish to continue this discussion, post your AI and your DXF files here for others with both software to help you dissect it more.

[maxim_k]

>>>>>I am assuming from what you said that these have no affect on the document itself as it's imported, exported, or saved

Correct

>>>>it's confusing as to why the default settings for AutoCAD would be set so that curves were jagged.

The curves are jagging only on screen, in fact they are curves. The settings for curves smoothing saved inside DWG file, but not globally in AutoCAD. So what you see on screen after opening DXF (DWG) exported from AI is AI job.

Once again - please, share your AI and DXF files here, we can look at them and will try to help you.

[Anonymous]

I have attached the DXF file in question, as well as the AI file. This is exported from AI with the settings you see above. 

Does anyone have the ability to open it in AutoCAD and see smooth arcs around perimeter of pieces and also perfect circles?

One of the most important features of AutoCAD is the use of DXF files. DXF is very important standard in the entire vector wold. The only reason i'm talking thoroughly about AI is to show that i have done nothing wrong in the export.

If autoCAD can't interpret a DXF correctly or is causing issues, then this is something that AutoCAD's team needs to be aware of. And with my case here, it is entirely possible that this is an AutoCAD error. I can not conclude that yet, but lets try to figure this out.

thanks

[Anonymous]

Additionally, i would like to add that Vendor A, a couple weeks ago, sent me a screen shot showing how his document looked within AutoCAD when he opened it. This was a direct DXF export from AI that i had sent him.

The curves were perfect, but the scaling was tremendously oversized.

So, this is when i signed up for AutoCAD in an effort to solve the scaling issues.

So, the fact that the curves translated to him from my direct AI DXF export, says to me that AI is doing it's job correctly exporting curves.

[maxim_k]

I opened DXF file you attached and have found that the circles in it were converted as Splines. But I believe your wendor wants them to be circles.
As I expected, export operation in AI don't work for you correctly.
For the moment I cannot test AI file, but will test it later:

[Anonymous]

thank you for the help. i truly appreciate it.

It's complicated, because it seems that somehow the direct export from AI was able to be opened up with curves just fine, by Vendor A a couple weeks ago before i used AutoCAD. 

This here attached is what Vendor A sent to me as a screenshot from their own AutoCAD system. This is a different file that I'm editing at the same time, but the same methods are used. The curves look to have translated as fully resolute, although they have of course some basic render quality for display purposes. 

They do not at all appear to be splined.

The issue they had contacted me about was scaling, a separate thing.

For what it's worth to the community here, i'm not looking to just solve this and use AutoCAD for transfers only. I am looking to develop a few 3D designs soon too. I'll be doing that completely within AutoCAD. But in general, i will need to remain capable of doing various imports and exports of DXF files. Different vendors use varying systems, including AI sometimes, and so i need to stay in tune with DXF format translations. So i'm very much hoping to simply understand how to maintain a good DXF file within the AutoCAD domain and a few major vector industry counterparts like AI, etc.

[pendean · Accepted solution]

Thank for the files: AI is indeed the wrong tool to create DXF content needs to be used by AutoCAD users. It appears the built-in translator in AI is making the conversions for you.

DXF files are just text files, open one up in your favorite word processor, circles do no exist in there. But there are lots of Splines. There is no conversion taking place inside AutoCAD with your DXF: that happened in AI's converter.

As noted, in AutoCAD the command REGEN or REGENALL will smooth out for Spline circular shapes so they do not appear too jagged. See below.

 

Not quite understanding the scaling issue unless your other recipient is INSERTing your DXF into a different-units-setting DWG file. AutoCAD has no preset units, a UNIT in a DWG file can be an inch, a mm, a mile, a lihtyear or a micro-whatever, the file creator makes that determination.

 

[maxim_k · Accepted solution]

Hi James,

I looked at your AI file.

Let's try another DXF conversion way.

But at first you need to remove all special effects from the objects in your AI file using Illustrator: I noticed that for some reason straight lines with rounded corners in your AI file have  Grain effect assigned:

1/ You have to remove this effect with Trash button. Then save AI file.

2/ Now in Finder change extension of your AI file from .ai to .pdf

3/ Launch AutoCAD and use menu File -> Import to import file you renamed in step #2

4/ Use standard settings in "Import PDF" dialog:

After importing PDF to AutoCAD you can save it to DWG and to DXF format. Just make scale adjustments with SCALE command.

I attached resulting DWG and DXF files I created in such a way for reference.

[Anonymous]

Thank you.

I am working on this all today, and will report back either later today or tomorrow.

Thank you so much!