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Exporting sketch as DXF - Scaling

chris_lineschris_lines Member Posts: 4
I am wanting to get a part laser cut. 

I set my units to mm, dimensioned a major length to 76mm, and exported a sketch as a DXF for laser cutting but the company receiving the file found the scale to be incorrect with the 76mm length being ~3mm.

How can I ensure I'm exporting the same scale as what is showing in the drawing? 

Answers

  • michael3424michael3424 Member Posts: 532 ✭✭✭
    That sounds like a unit conversion issue - 76 mm/25.4 mm/inch = 2.99 inches.  
  • jakeramsleyjakeramsley Member, Moderator, Onshape Employees, Developers Posts: 624
    His chris_lines,

    Can you clarify where you are exporting the DXF from?  I see you say you are exporting a sketch, but then later on you talking about the scale on the Drawing.
    Jake Ramsley

    Director of Quality Engineering & Release Manager              onshape.com
  • chris_lineschris_lines Member Posts: 4
    Michael - Yes, there must be a conversion to inches somewhere but my units are set to mm and my dimensions are in mm.
    Jake - To export the DXF I am right clicking the sketch in the features window then selecting "Export as DXF/DG". Apologies, when I stated 'Drawing" I meant "Sketch".
  • jakeramsleyjakeramsley Member, Moderator, Onshape Employees, Developers Posts: 624
    Can you try round tripping the DXF back into Onshape?  As far as I know, there is no information in the DXF file for unit types and it is up to the importer to handle it.

    1) Upload the .DXF back into your document
    2) Start a sketch and choose 'Insert DXF or DWG'
    3) In the insert dialog, choose the units 'mm' at the bottom and then select the DXF that you uploaded.
    Jake Ramsley

    Director of Quality Engineering & Release Manager              onshape.com
  • chris_lineschris_lines Member Posts: 4
    When inserting the DXF into a new document, with default units set to mm, and upload of the DXF into a new sketch with 'mm' units results in a scaled down sketch to that exported previously. When uploading the DXF into a new sketh with 'inch' units, the result is a sketch to the correct scale. 

    This leads me to believe an export of a sketch to DXF takes the units as inches, regardless of the default units.
    Surely it would be possible to export a DXF with 'mm' units with a minor software change? 
  • jakeramsleyjakeramsley Member, Moderator, Onshape Employees, Developers Posts: 624
    When inserting the DXF into a new document, with default units set to mm, and upload of the DXF into a new sketch with 'mm' units results in a scaled down sketch to that exported previously. When uploading the DXF into a new sketh with 'inch' units, the result is a sketch to the correct scale. 

    This leads me to believe an export of a sketch to DXF takes the units as inches, regardless of the default units.
    Surely it would be possible to export a DXF with 'mm' units with a minor software change? 
    DXF's are round tripping for me correctly (my document: https://cad.onshape.com/documents/9baa14fea3314fe2a9e9928a/w/9fcd4168ca6a4e94a688d7ba/e/bac3de33d9964a2791cbc528).

    1.  I set my units to be millimeters and made a sketch with a circle and a spline in it.  I right clicked on the sketch and chose to export as DXF.


    2. I re-uploaded the .DXF and started a new sketch.  I chose insert DXF and selected my file with the unit type being 'Millimeters'.  The result is that the sketch made from the DXF is the same size as my previous one.


    If you are willing, can you send a ticket via feedback and share with support?
    1.png 106.1K
    2.png 164.6K
    Jake Ramsley

    Director of Quality Engineering & Release Manager              onshape.com
  • chris_lineschris_lines Member Posts: 4
    Jake - I have just re-tried the entire export-import process as it seems to work as you have also achieved. I have sent the new DXF to my manufacturer for confirmation that the scaling is correct. 
    I am unsure how this error occurred initially though, as my default units have always been set to 'mm'.
  • jakeramsleyjakeramsley Member, Moderator, Onshape Employees, Developers Posts: 624
    Jake - I have just re-tried the entire export-import process as it seems to work as you have also achieved. I have sent the new DXF to my manufacturer for confirmation that the scaling is correct. 
    I am unsure how this error occurred initially though, as my default units have always been set to 'mm'.
    Glad it worked.

    If you are interested in investigating, the change of units is stored in the history of the workspace you are in.


    Jake Ramsley

    Director of Quality Engineering & Release Manager              onshape.com
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