Simplifed parts have same mass as parent

[jmenier]

Ever since "level of detail" was removed from inventor, I have had the same problem with determining weights of isolated portions of frame assemblies. I thought of a good workaround where to determine a weight and COG I would create a simplified part from the parent and that would surely update with a correct mass and COG. Well it does not, unless if there is some button I am not pressing in the simplify window. Can anyone help? Attached is the an assembly and the simplified part below with the same mass and COG. Any one know how to achieve what I am trying to do surely gets a gold star! If not, Inventor team, can you guys figure out how to make "representations" work in frame assemblies, quickly please.

[b.mccarthy]

Can you share your assembly?

[jmenier]

I could, but this issue is not "this" project dependent. This happens with any frame generated assembly. Simplify does not alter any mass properties in a frame assembly. Any ideas as to why?

[blandb]

You can set your Tools > Application Options > General Tab > Physical Properties > Update Physical Properties on Save for parts and assemblies. Now if you suppress and save it should update your COG. Please see attached video to see if it helps you.

[jmenier]

Appreciate the reply, but I need to be able to put the different levels of detail onto drawings and show mass according to the parts not suppressed.

[johnsonshiue]

Hi! Instead of using Simplify, you may derive those components into a new part. Then the mass prop will be based on the derived geometry, not the source geometry.

Many thanks!

[b.mccarthy]

This is somewhat tedious and verbose, and it may or may not address your needs...

1. Generate a step file from your main assembly, Assembly 1 in this case. I have an iLogic routine that fires on "Before Save Document" so that the step file is always current
2. Open the step file and choose "Reference Model" under Import Type. Save the model as Assembly 1a
3. Return to Assembly 1, activate or drill down into the frame, suppress the needed components. Return to top level and save the model
4. Return to Assembly 1a, and update it, and the CG will update.

Any changes to your base assembly will be reflected in the secondary assembly.

Assembly 1:

Assembly 1a:

Assembly 1 with frame members suppressed. CG does not update:

Assembly 1a after updating the model. CG updates:

There are issues with the BOM of course...

Assembly 1 BOM with suppressed members:

Notice the zeros for the suppressed members. These cannot be turned off, although they can be hidden in the parts list.

Assembly 1a BOM:

Notice that there are no zeroes, however the "Unit QTY" and "QTY" columns do not report correctly.

Drawings are a different story:, see attached.

Hopefully some of this will help, or perhaps lead you in a different direction, at least until Autodesk fully fleshes Model States so that they function as we expect and need them to...

[jmenier]

Johnson, I wish Autodesk people wouldn't give non-answers like that... Correct me If I am wrong and I'll apologize for calling this out if I am, but a derived part doesn't keep any material properties. All derived assemblies parts switch to material type "Default" and turn into solids rather then parts. So the entire derived part would have to be reassigned to the original material to make an accurate COG and Mass work. But, as often in my case, an assembly with dissimilar materials this wont work. You would need further steps/editing. I would have to make the derived part into a new assembly and then still reassigning all the materials while suppressing or deleting the parts needed for the representation I need, and then I think it would loose its relationship with the original model.

We need a better fix.

[jmenier]

@b.mccarthy, way to find that workaround but I'd rather eat my hat! JK, I think a simpler process would be to go into design accelerator and make a complete copy into a new folder in the project, then delete parts as needed to get my view. But then this breaks the relationship to the original model, I didn't try your method but I am almost positive that exporting it will break that link too.

[b.mccarthy]

I have a hat in case you run out...

[johnsonshiue]

Hi @jmenier,

I have re-read the posting. I have to apologize that I misunderstood the request. I thought you were talking about Simplified component carrying the source assembly mass prop. I thought you would want to untangle the link.

Actually, you would like to evaluate Massprop/COG of some components in the assembly. There isn't a one-click workflow in this case. You will need to suppress the unwanted components and then update Massprop/COG.

Many thanks!