Exporting sketch as DXF - Scaling

chris_lines

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? 

michael3424

That sounds like a unit conversion issue - 76 mm/25.4 mm/inch = 2.99 inches.  

jakeramsley

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.

chris_lines

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".

jakeramsley

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.

chris_lines

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? 

jakeramsley

chris_lines said:

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?

chris_lines

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'.

jakeramsley

chris_lines said:

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.

Gerard_Boterman

I believe Onshape has some export issues.
I am trying to export 2d profiles of a model, there is not option to do this from the Part Studio. So I created a drawing using one of my A3 (blank) Templates, but, this scales everything down to fit the size of the A3 sheet.
As work around I open the sheet and set scale it 1 : 1, which then will exceed the paper size, but it shows the profile 1:1. If you then right-click the sheet tab, you can actually export the profile at real size.
Currently I am not sure how to do it in a more obvious way as can be done in SW. It would be nice to see the export of DXF/DWG at 1:1 improved in Onshape - Gerard

nick_papageorge073

Gerard_Boterman said:

I believe Onshape has some export issues.
I am trying to export 2d profiles of a model, there is not option to do this from the Part Studio. So I created a drawing using one of my A3 (blank) Templates, but, this scales everything down to fit the size of the A3 sheet.
As work around I open the sheet and set scale it 1 : 1, which then will exceed the paper size, but it shows the profile 1:1. If you then right-click the sheet tab, you can actually export the profile at real size.
Currently I am not sure how to do it in a more obvious way as can be done in SW. It would be nice to see the export of DXF/DWG at 1:1 improved in Onshape - Gerard

There are no scaling issues. I've sent about 100 different parts to various laser and waterjet vendors over the past two years, and they have all come back perfect. You can either right click on a face in a part studio and select export as dxf, or, make a 2D drawing full scale, and export the whole drawing as a dxf using the tab at the bottom of the screen. Of course with the latter, you'd want to delete all the drawing border/title block/rev block, to make it simpler for the vendor.

wayne_sauder

I agree with Nick there are no issues, but one thing to note is if you select a face and right-click export a dxf (the fastest cleanest way to get your dxfs) make sure you tick the box to set z heights to zero. Before I started doing that all the time I did have a supplier that had troubles with my files.