IGES import in wrong units

[keithd]

I imported a .igs file into Fusion 360 and was able to turn it into a real 3D model using the patch facility.

The only problem is that the model is in the wrong units. For example, if I measure a hole it shows a radius of 2.00 inches. But the actual dimension is 2.00 mm.  Changing the units of the model space to mm simply tells me the dimension of the hole is now 50.8mm (2.0 * 25.4)

Is there any way to correct the actual units of the model?

Thanks,

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Keith

[HughesTooling]

I just did a test using Rhino and exported a file in mm and one in inches and Fusion read the units correctly from the igs file. What program are you exporting the igs file from, do you have a file you can share here?

Mark

[keithd]

It's a file I downloaded from the Web. I know nothing about it or what program generated it.

The problem could easily be an error in the IGES file, not in Fusion 360. But I have no control over the source file and there is zero hope of finding someone who could or would fix it.

So I was wondering if there was anyway to redefine the units once in Fusion.

I've seen this problem before when importing into other drawing packages. I suspect the problem is that the creator does not record the units type in a way that the importer can read it, so the importer simply assigns the units to its default type. If it is a common problem then it would be nice to have a way to override the default assignment, just as a way to maximize a user's ability to deal with foreign files.

Thanks for the test.

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Keith

[Phil.E · Accepted solution]

To convert inch to mm, scale the bodies by 1/25.4, or 0.0393700787401575.

50.8mm x 0.0393700787401575 = 2mm.

Scale is on the Modify menu. Please let us know if you have more questions.

Thanks,

[HughesTooling · Accepted solution]

You can just type 1mm/1in in for the scale factor.

Mark

[keithd]

Thanks. That worked fine.

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Keith

[keithd]

Thanks. Even easier.

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Keith

[samuel.sudhofKWJYQ]

I know this is an old topic, but it's the first google hit for this issue, so I will add some explaination here. If Fusion fails to read an IGES file's header, it discard the header information completely, and uses built-in default values for all fields. This happens to be inch for the unit field, which is part of the header.

You may be able to fix the problem just by looking at the header and comparing it to the public IGES specification.