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Full Version: Moi3d dfx export issues

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From: Michael Gibson
27 Sep 2022   [#6] In reply to [#2]
@ Brian,

re:
> (MoI has a Save AS dxf, and also an Export to dxf. (I do not know what the difference may be, if any.)

The difference is that Export is short for "Export selected objects" - it writes only the selected objects out to the file you specify.

"Save As" on the other hand does all objects not just selected ones.

- Michael
From: bemfarmer
27 Sep 2022   [#7] In reply to [#6]
Thank you Michael,

I'll second Burr's 1:25.4 setting in SheetCam, indicates 1 inch = 25.4 millimeters. It seems that sheetcam expects or relates millimeters and inches. (or custom)
So using cm in MoI dxf export/save accounts for a scale factor of 10.
The small portion of the scale factor, perhaps ~ 0.16 +/-, seems to be some typical problem with scale in Fusion, a different Cad than MoI.
A 2020 Adobe Illustrator version had some recurring scale "bug" also.
https://illustrator.uservoice.com/forums/601447-illustrator-desktop-bugs/suggestions/42476125-dxf-files-not-coming-in-to-scale
It is funny to me that Illustrator keeps reintroducing the same(?) scaling "bug".

I have no idea why Save dxf might be better at scale than Export dxf, or if there is no difference in MoI.
Hopefully an example .3dm will be supplied, for testing.
(I'll resist making more comments, due to lack of knowledge :-)

- Brian

Ok, one more link, re Inkscape scaling problems:
https://inkscape.org/cs/forums/questions/how-to-export-dxf-with-correct-scale-dxf-is-exported-with-incorrect-sizescale/

I've read that the 2018 version of dxf is the one to use for dxf.

https://forum.onshape.com/discussion/17533/dxf-export-issues

https://forum.onshape.com/discussion/comment/72481#Comment_72481
Quote: "DXF and STL are both very popular CAD file formats. The other thing that they have in common is that they don't specify the units. The amount of money and time that has been wasted in the world because of this is insane.
Make sure to tell whomever is importing a DXF what units were used for exporting. As an extra check, add some reference feature and call out that it's 10mm (or another appropriate round number) long."

Quote:
Onshape always exports with the dimensions set to that the document is set to - to make sure I'm making sense, if I have a line in my drawing or sketch that has 500mm, the resulting DXF will say 500 (no unit) then in that $INSUNITS header it will say "1" for inches, so some software will load that line as 500 inch.
From: Matadem
27 Sep 2022   [#8]
Good day.
It seems when drawing in 1200mmx2400mm Moi will export and import in sheetcam just fine.

but not when drawing in cm. 120cmx240cm

Attached the file drawn in cm and a pic how small it turned out in sheetcam
the red square would be the material with a size of 48"x96"

and a pic of one drawn in mm attached as well.

Thank you!

Attachments:
export in cm.3dm

Image Attachments:
import in cm.jpg  import in mm.jpg 


From: Michael Gibson
27 Sep 2022   [#9] In reply to [#8]
Hi Matadem, thanks for posting the file.

It sounds like you have found the solution - for export into Sheetcam you should set your units in Moi to mm before you make your DXF export.

When MoI writes out a .dxf file, it does set a property in the .dxf file called $INSUNITS which many programs will look at to know what unit system the DXF file should be processed as. You may want to contact Sheetcam tech support and ask them to also look at that $INSUNITS setting in the .dxf file so they could handle importing a DXF file with cm units set in it.

Another option is that it looks like Sheetcam has a "custom" setting for how to process the units in the DXF file. If you have generated a DXF file that is in centimeters you can probably use the "custom" setting in Sheetcam with the right scale factor put in to make it load in ok. Sheetcam tech support can probably tell you what scale factor you will need to do it that way.

- Michael

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