Scaling issue after stp file has been imported

[kristofszigeti1]

Hi there,

When I import, it seems as if the inventor changed the original model scale. Why does it happen or what do I miss?

There is a length 73,118 mm but Inventor says it is 2,868. 

[EdvinTailwind]

I think it's a metric versus imperial issue.

1 inch= 25,4 mm

2,868 * 25,4 = 72,8472

That is very close to your expected measurement. The deviation of 0,2708 could be depending on the precision during export and import of the STP.

[kristofszigeti1]

It is close and this must be the issue, but a bit unexpectable, that is why I'm surprised.
btw obj file seems properly (in the right scale) imported. I might be able to working with this in this situation. 

[EdvinTailwind]

In worst case you could create a derived part and scale it by 25,4.

[JDMather]

@kristofszigeti1 

You mention stp and obj.

stp units usually specified from source

obj no units and often rubbish

Attach your original file(s) here and end all doubt.

The should be a logical reason/solution.

[johnsonshiue]

Hi! STEP file is unit sensitive. Unless the unit is incorrectly specified in the file, I don't think the model will rescale. I guess you were talking about the original source being mesh (obj). And, it was imported and converted to a solid body. Then it is exported to STEP. The rescaling probably happen during obj import.

Please share the file here. I would like to understand the behavior better.

Many thanks!

[kristofszigeti1]

Let me share you some files.
The task is: There are plenty of hollow section parts which designed in Tekla Structures and all of them need to be handled by hand-sawing process, so I would like to make a cover or a mask to mark the proper line for it. After importing they are supposed to be unwraped and exported to 1:1 dwg/dxf, but they seem like smaller as I expected and the ratio is around the imperial <-> metric conversation.

It is supposed to be right. I am pretty rookie user of Inventor, so I must miss something! 

[johnsonshiue]

Hi Kristof,

The STEP file is based on mm. You can open it in Notepad to check the coordinates. They are all in the range of hundreds of mm, which is consistent with the measurement of the STEP imported geometry in Inventor and viewer.autodesk.com.

I suggest you look into "Open CASCADE," since the STEP file was exported by the tool. There could be some setting to change to ensure the proper scaling.

Many thanks!

[JDMather]

@kristofszigeti1 

OK, 

Let's back up and establish some base information.

The Units in your DWG file is Inches

The Units in your *.ipt is also inch.

Do you want inch units or do you want metric (mm) units?

[kristofszigeti1]

mm values is needed in all of the files and documentations.
I am pretty newbie at using Inventor, I guess I confused myself, too. Skipping a basic step or something like this.
Thank you for helping me out!
 

[JDMather]

@kristofszigeti1 

How are you “opening” the stp file?

Are you doing File>Open directly

or

are you Importing into an already open file?

[kristofszigeti1]

Just import the stp file just as it has been exported from Tekla.
Starting Inventor, opening a session by the "Part" button, and after that importing stp, setting multi-body part and selecting the stich option from the drop-down menu.

[TheCADWhisperer · Accepted solution]

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@kristofszigeti1 wrote:

Starting Inventor, opening a session by the "Part" button, and after that importing 

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@kristofszigeti1 
Stop.

Do you normally work with metric units?

It sounds like your default template is set to inch units.

We can change the default units if you normally work in mm.

But if instead of starting the way you describe, don’t start a New Part. Don’t Import.

Go to File>Open and select Files of Type *.stp and open directly rather than importing into an already open file.

Let me know if you want to change your default units.

[JDMather · Accepted solution]

To Open the *.stp file directly ...

To change Default Template (for all future work)...

To change (or check) the Units of existing work...

[kristofszigeti1]

Thank you very much!
(I will keep on learning.)

[kristofszigeti1]

Thank you very much!
(I will keep on learning)