I imported a dxf file from CorelCAD. This was simple drawing of a zodiacal symbol; Capricorn.

(At first I used the REGION command in the CAD program to create a 2D surface to extrude, but when I attempted to import that into MoI, it was blank with no error message. Can you not import a dxf drawing of a region?)

I imported a dxf of the image up to the step before I created a region

After several attempts I was unable to extrude this shape so that the result was a solid. All I could do was extrude the "sides". I am looking for a result with a flat surface.

I assume there was some step missing? but I cannot see what that might be.

In the demo of an extruded star the star has a 'top'. Why doesn't this? (see attached)

I hope this can work because the idea is to use MoI to extrude drawings that come in from a CAD program and not to create anything wholly within it.

Thanks


Andrew

Hi Andrew,

Are you sure, your curve is a closed curve ?
If this is a closed curve some points could be at same place. You can rebuild it or reconstruct with RecnstructCurve plugin.
Could you post your 3dm file to see where is the problem.

Hi Andrew, yes please post a .3dm file with your curves in it instead of only a screenshot. That then makes it possible to do a detailed analysis of your objects and give you more accurate advise on what is going wrong.

There are a few different things that can make you only get "side walls" on an extrusion like that, it can happen if your curve isn't planar, if it isn't closed like if there is a gap between the starting and endpoint, or also possibly if it isn't well formed like if it has any areas where it is self intersecting. If you could post the .3dm file it would be possible to examine your object more closely to determine exactly what is going on.

3D modeling operations are more sensitive to defects such as self-intersection than 2D illustration use and it's not too unusual for curves done in a 2D illustration program to need some amount of cleanup work to improve their geometry before they can be used directly for 3D model construction.

- Michael

Thank you both for your replies. Your request to post the .3dm file of the drawing makes sense and is generous of your time.

Unfortunately, I am working with the no save trial version, so I am out of luck there.

However, If I can successfully convert this closed curve into a region and extrude it in a separate CAD program (and I can) then the drawing is 'clean', otherwise, it would not be possible to create a region.

I do not understand why I can save the CAD drawing as a region in dxf format but cannot open it in MoI. Can't MoI extrude regions brought in from a CAD drawing?

Andrew

Hi Andrew,

re:
> However, If I can successfully convert this closed curve into a region and extrude it in a separate CAD
> program (and I can) then the drawing is 'clean', otherwise, it would not be possible to create a region.

Not necessarily - there are a lot of variables. It could be that the separate CAD program uses a looser tolerance than MoI for forcing things closed, or if it is some problem with self intersection it can by luck sometimes appear to be ok.

Since you can't post the .3dm model file I would recommend to instead post the .dxf file that you are trying to import. That would also allow me to do a detailed analysis of your geometry and see what's going on. Or if it is a bug in MoI's import handling I would also need to repeat the problem over here to have any chance at fixing the bug.

With just a written description or a screenshot it's not really possible to give you any more information than I already have.

- Michael

Hi Andrew, also re:

> I do not understand why I can save the CAD drawing as a region in dxf format but cannot open it in
> MoI. Can't MoI extrude regions brought in from a CAD drawing?

Sorry I think I originally didn't understand this part - are you referring here to the Region AutoCAD entity?

MoI will currently read line, circle, arc, point, lwpolyline, polyline, ellipse, and spline entities from .dxf files. It doesn't try to process Region entities. If you have an example file that is not working please post it or e-mail it to me at moi@moi3d.com if you wish to keep it private so I can take a look at it.

- Michael

On further investigation I discovered that although I could make a region in the CAD program, I cannot extrude it. So, I must sort that problem before exploring MoI any further.

Thanks for all your replies.

Andrew

Hi Andrew, no problem. And if you need help figuring out why it won't extrude please post the .dxf file here or send it to me at moi@moi3d.com .

- Michael

Hello Michael:

Many thanks for this. The culprit is attached.

It may help to know that this drawing, originally a CAD drawing, was opened in CorelDraw and cleaned up, i.e. to give it smoother curves. It was then saved as a dwg file and that is what I opened.

It might help to explain in some detail why there is an interest in MoI in the first place, i.e. how we plan to use it in our business. What we are really trying to ultimately understand is what is the best work flow. Maybe later, but first things first.

Many thanks again

Andrew

Hi Andrew,
I have run the rebuild command on your curves and they extrude Ok.
Hope this helps.
Barry

The dxf has something "wrong" with it.
Selecting the top extruded edges and joining them to a curve, and replacing the dxf with said edge, yields successful extrusion...

Hi Andrew, thanks for posting the file. So it looks like the main problem is that there are spots on the curve that have a series of control points stacked up right on top of each other. That's something that will tend to cause problems for 3D CAD use of the geometry.

If you select the curves in MoI and use "Edit > Show pts" on them there will be a red square displayed around each location with stacked up control points.

If I remember right I think there is a method built in to PDF/AI8 file import to try and clean those up so one thing you might try to start with is to save from CorelDraw as a PDF file and open that rather than DXF format.

Or actually even saving to PDF from MoI and then loading it back from the PDF file will do that, that's what I did to the attached file which should work ok now.

- Michael

Basically the MoI PDF and AI8 importers are set up to try and deal with stuff that is often problematic from 2D vector illustration programs while the DXF importer doesn't, it's expecting the stuff in the .dxf file to have been drawn in a CAD program instead of in an illustration program.

So from CorelDraw you would want to use either PDF or AI version 8 file formats for transferring from Corel into MoI and that should work better.

- Michael

Barry
Many thanks for this. Where is the rebuild command? I do not see it in MoI.
Thanks
A

Many thanks for your reply.

Andrew

Michael,

I went ahead and saved the drawing in CAD as a PDF but still it failed. I think this may be because the dxf original I opened came from a graphics program. At least the PDF, when opened in MoI, did not have those nodes on nodes errors. So, it seems that you are saying to leave that step out, i.e. to open the drawing in CorelDraw, clean it up and save it straight to a PDF. Correct?

You may wonder why I do not just go ahead and try that myself, but I am collaborating with someone else who works in that program.

Thanks

Andrew

hi Andrew,
select the curves you wish to rebuild press the tab key and type rebuild press enter, the options for the rebuild will appear top right.

Barry

Hi Andrew,

re:
> So, it seems that you are saying to leave that step out, i.e. to open the drawing in
> CorelDraw, clean it up and save it straight to a PDF. Correct?

Yup, that's correct. Basically for any transfer from CorelDraw to MoI use PDF format for the transfer instead of DXF. But when transferring from a 2D CAD program to MoI that's when DXF would usually be preferred.

The problem happens with curve segments in CorelDraw (and other 2D illustration apps) that have a tangent handle on one side but none on the other side. That makes a bezier segment of 4 points but with 2 points stacked up on the non-tangent-handle side. Most 3D CAD programs do not like to have that kind of stacked up control points on curves, it kind of degrades some of the mathematical properties of the curve at that spot.

When MoI opens a PDF file or AI version 8 file it will look for those and tweak them slightly to avoid the stacked up control points. It doesn't do this for every kind of file open because that tweaking does make for a very small change in shape and usually MoI tries to be pretty conservative and avoid modifying things that changes the shape of things at all.

- Michael

Michael:

First, my apologies for not replying sooner to thank you for your detailed answer. (Not that I understood it all!) My situation is a bit complicated, not to say unusual, in that I am actually collaborating with someone who is on one side of the Atlantic while I am on the other. But, as our English cousins say, "it's needs must".

The pdf that was sent did work and worked well. I am not sure, though what you meant when you said that "It doesn't do this for every kind of file open..." Do you mean that it will not always for pdfs, or not always work for other file types?

We are trying to establish a workflow for the ultimate creation of stl files to drive our CNC machine. At this point I create the wireframe or armature as it were. Next, my English colleague uses this to create the design using his graphic software (CoreDraw), he sends the result back to me as a pdf file and then I use MoI to create the stl file. What I really like about this is that it completely sidesteps the use of a CAD program, something I have often found like using a sledgehammer to drive a tac, att least as far as our purposes are concerned.

Thanks,

Andrew

Hi Andrew,

re:
> The pdf that was sent did work and worked well. I am not sure, though what you meant when you said that
> "It doesn't do this for every kind of file open..." Do you mean that it will not always for pdfs, or not always
> work for other file types?

Yes I meant not for other file types. It will do it always for PDF and AI files.

- Michael