Why Are Fusion Dimensions 10X greater on imported .STL files?

[lorne01]

I tried out Fusion 360 this evening.  I found it odd that every .stl i imported had the dimensions wrong.  I verified with Sketchup, and sketch up has the dimensions right.  I have figured out that the dimensions are out by a factor of 10.  

Is there some setting or something that needs to be changed to get the proper dimensions?  

The picture attached is of a ruler that is verified in Sketchup to be 10mm (length of the green line, but in Fusion it is 97MM.  Does this mean all my prints will be 10X bigger than they should be and i will have to mentally adjust for the error?  

I would appreciate if you have any insight.  

[Phil.E]

Hi,

I'll try the workflow.

Just to be clear, your image with expected spacing is measuring a file called 'Test - Wemos...', but in your second image the linked (after insertion from data panel) the giant file you are measuring is called 'Wemos...'. 

Did you perhaps insert the original file that was already 10X sized? What happens when you insert 'Test - Wemos.."?

Thanks,

[Anonymous]

Phil,

Thanks for the rapid reply!

EDIT / UPDATE:

Phil, I just went back and double-double-checked. And this is what i find. (Not bothering to upload photo since it's the same..) When I go through the steps you outlined, the mesh imports apparently correctly. I can measure the space between the pins and all seems correct. When I go to USE it however, it imports with the 10X size. Also, if I simply re-open the part that I created, it also opens with the 10X size.

So yes, there is a separate image from an earlier attempt today, but the results / issues I'm reporting is still the same.

Thanks for noticing.

John

[Anonymous]

I just tried it again and this time it worked. I don't know what I did that was different though. I shut down the program and then I decided to try it one more time and fired it back up and it imported correctly and is working correctly:

[Phil.E]

Thanks for the update and I'm glad it's working. I just tried the workflow and found it to be working as expected. So I'm glad we are not seeing different results.

For the record, here are the steps I took:

1. Download the file from thingiverse.

2. Start a new Fusion 360 file and use the Insert > Mesh command from the Insert menu.

3. Pick mm units in the insert dialog.

4. Save the file.

5. Start a new file, and units don't really matter (I confirmed this using inch units in the destination file), save it.

6. Right click on the file you just saved in the data panel, pick Insert.

7. Measure inside the inch file, and I find the pins are 0.100" apart, which is 2.54mm.

Thanks and since you were getting some strange results, please let us know if you see this problem again.

Regards,

[Anonymous]

Thanks, I will. And I appreciate your assistance!

john

[lichtzeichenanlage]

Side note: STLs do not have a "physical unit" as a base for the content.

Source Wikipedia:

An STL file describes a raw, unstructured triangulated surface by the unit normal and vertices (ordered by the right-hand rule) of the triangles using a three-dimensional Cartesian coordinate system

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All the STL files I've seen, are exported with mm in mind. So it looks like, that switching the document to mm. At least if it comes to 3D printing.

[Anonymous]

As of 11/25/2018, I experienced the same issue with model being 10x larger in cura after uploading an OBJ file from thingiverse and saving it as an STL.

Worked: I went to Document Settings under the Browser Tab and changed the units to CM. 

Did Not Work: Changing units to MM or Inches.  

Thoughts:  After reading this forum, there seems to be an issue with units of measurement just like most people are saying.  If changing to one unit doesn't work, try a different one. I'm currently printing the obj file that I want and it seems to be at the right scale.  

I thought about scaling object in cura to 10%.  This might actually work to.  I just wasn't sure how accurate it would be so I went this route first.  

[HughesTooling]

@Anonymous Best advice is don't upload the model, use Insert Mesh from the insert menu. Most mesh models you get for 3d printing will be in mm, uploading through the data panel will default to CM as the units so 100mm will import as 100cm (1000mm). Insert Mesh also give you the option to set units as you import.

Mark

[Phil.E · Accepted solution]

Thanks @HughesTooling you are correct.

The best way to create a design in Fusion that contains a mesh is not to use "upload", instead do this:

1. Download the file from thingiverse.

2. Start a new Fusion 360 file and use the Insert > Mesh command from the Insert menu.

3. Pick mm units in the insert dialog. (or whatever units provide the correct result)

4. Save the file, it is now a Fusion 360 design, containing a mesh that is scaled to the right proportions (which is what you were trying to achieve by using "upload").

The difference is that Upload assumes all unitless files (.stl or .obj) are made with CM units, and Insert Mesh allows you to pick the units which as Mark points out are generally MM, and thus the right result is easy to achieve. 

Thanks and please let me know if you have more questions.

Regards,

[Anonymous]

Thank you. I tried that way and it works great.

[steven2BAQB]

1. Importing STL should display an informative dialog box with the assumed dimensions.
2. The default import unit is cm, but it should be whatever is set for the current document, or should allow the user to set it just as import mesh does.

[chrisplyler]

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@Anonymous wrote:

And two years later, this is still not fixed...

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How can it be "fixed" if the problem is that the file type doesn't contain any unit information?

You think the Fusion 360 team can call up the Sketchup team (and all the other software teams that have developed software that can output an stl file) and get them all to change their software (and additionally, to band together and change the stl file format standard)?

Go ahead...tell us how it could be fixed.

[steven2BAQB]

The issue is not the STL format, it is the Fusion open dialog that makes some very unintuitive, undocumented, inflexible, and non-informative decisions.

[Anonymous]

Okay, here's how it could be fixed. It could pop up a dialog to explain the issue (no dimensional data), explain what the default is assumed by Fusion 360, and point out in the dialog that other programs might use different defaults. All of this would simply serve as a reminder to check what the units are. Another thing that COULD help QUITE A BIT would be to maybe temporarily / quick render the part to be imported alongside the other parts in the document so the user could get an immediate visual feedback of whether the dimensions seem right or not.
You might say-- why go through all this bother? I would say because Fusion 360 is aiming to be the CAD suite that "just works" for people.

[lichtzeichenanlage]

@Anonymous : But all this is true for your import side, too. I'ts doing the same assumptions. 

[Phil.E]

Thanks for all your comments about this issue. To be honest is very unlikely we will change this any time soon. 

If you want unit control, use a new document, and use Insert Mesh. Pick units. This gives you a new document of any scale.

If you are inserting it into an existing design, the same holds true.

@Anonymous You seem to be mixing these workflows. If there are other objects in the design already, then you must be using Insert Mesh which allows you to "quick render the part to be imported alongside the other parts in the document" as you ask for. This workflow already exists.

A quick search of google shows the Insert Mesh solution in the top two answers. We hope that people looking for this information can find it.

Thanks again for your passion and suggestions, I just want you to be clear about this situation.

Regards,

[chrisplyler]

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@steven2BAQB wrote:

The issue is not the STL format, it is the Fusion open dialog that makes some very unintuitive, undocumented, inflexible, and non-informative decisions.

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Ah, okay. That's fair enough!

[steven2BAQB]

It would also help to show the bounding box dimensions when opening or inserting the item, especially because Fusion currently has no way of showing the dimensions of a mesh.  You have to manually measure arbitrary points to get that information.

I needed to edit an STL and re-export it;  It was remarkable on how much time was wasted before I did the workaround by importing the mesh (in a different menu) instead of opening it.

[steven2BAQB]

With all due respect, I think the intuitive workflow is:

1. Open a document
2. Edit it
3. Save It

And expect what you save to be pretty much the same as the original, not 10x different in scale.

[chrisplyler]

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@steven2BAQB wrote:

With all due respect, I think the intuitive workflow is:

1. Open a document
2. Edit it
3. Save It

And expect what you save to be pretty much the same as the original, not 10x different in scale.

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With all due respect, I think the logical deduction is that:

Since the STL file format has no unit information...if you open one, edit it, and save it again as an STL...that saved file will also not have any unit information, and as such will still be substantially the same as the original file.