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Strange Assembly behavior - parts won't move that are not fully constrained

13 REPLIES 13
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Message 1 of 14
fourholesn1
8552 Views, 13 Replies

Strange Assembly behavior - parts won't move that are not fully constrained

Can someone at Autodesk take a look at a pack n go? This assembly has piping parts that are not filly constrained yet will not move. For example a Tee that has only its centerline mated to a pipe centerline acts like it is fully constrained or grounded. I can demote those parts into a sub-assembly and then they behave normally. I'm wondering if this assembly has some kind of bug, even though no errors are reported and rebuild all doesn't help. Is there any kind of other program that goes through an assembly file and cleans up bugs? Any help would be appreciated. The pack n go is 65 MB so someone will need to tell me where I can send it.
13 REPLIES 13
Message 2 of 14
admin
in reply to: fourholesn1

Just curious. Do you have the LeaCar addin installed?
Message 3 of 14
fourholesn1
in reply to: fourholesn1

I guess not....don't see anything like that in my add-in list.
Message 4 of 14
Anonymous
in reply to: fourholesn1


If your assembly has IPT files that are not
properly constrained, you will have this problem.


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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
I
guess not....don't see anything like that in my add-in
list.
Message 5 of 14
fourholesn1
in reply to: fourholesn1

What is the definition of "not properly constrained"? Surely you can insert a part and not have it be FULLY constrained so that it may be free to move in one direction.
Message 6 of 14
JDMather
in reply to: fourholesn1

I suspect parts can be built without any dimensions and/or constraints and the assembly constraints will work just fine. You problably have something wrong in your assembly constraints or adaptivity between parts.
I'll bet the problem could be reduced to a handful of parts (probably just two) within the assembly.

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Message 7 of 14
Anonymous
in reply to: fourholesn1


Don't ask me why, but a loosely constrained IAM
file will do this. I ussually start looking at all my IPT's to see which one is
not properly constained.


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style="PADDING-RIGHT: 0px; PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #000000 2px solid; MARGIN-RIGHT: 0px">
I
suspect parts can be built without any dimensions and/or constraints and the
assembly constraints will work just fine. You problably have something wrong
in your assembly constraints or adaptivity between parts. I'll bet the problem
could be reduced to a handful of parts (probably just two) within the
assembly.
Message 8 of 14
fourholesn1
in reply to: fourholesn1

I'll talk to the user but I think he does have quite a few partially constrained parts. I'll ask him to constrain everything and see what happens. I have to say though, I think Autodesk should address this. In this design situation (piping runs) I think partially constrained parts makes sense.
Message 9 of 14
denl
in reply to: fourholesn1

Can you send a sample iam file with all your ipt files and indicator which part has problem when you has one constrain? You can send them directly to me at lisa.den@autodesk.com

I will let you know what I find after I take look the files.

Thanks.

Lisa Den (Autodesk)
Message 10 of 14
dan_inv09
in reply to: fourholesn1

The problem is to many things are partially constrained. Inventor has to try and figure out how to many things can move and gets bogged down.
Once you get a part of the run settled, try constraining whatever you can. Or, an easier way is to ground things that don't affect what you are working on right now. Sometimes just grounding one part is enough, if it locks down most of the parts the ones you need to work with will behave properly.
Message 11 of 14
denl
in reply to: fourholesn1

Thank you very much for the information. I can reproduce your issue on my machine. I logged the issue into our tracking system. The developers will take look it. The DID is 1154697.

Thanks.

Lisa
Message 12 of 14
ian.culhane
in reply to: denl

I am also having a similar problem with an assembly I have. Parts that are not grounded or fully constrained act as though they are grounded and will not move. I have tried deleting one of the faulty parts and then re-contraining it and I still have the same problem, so I don't think this is the issue. 

Message 13 of 14
blair
in reply to: denl

Check for "Sick" constraints in your IAM file. To the right of your Joints and Constraints icons are three icons, if the middle one (highlighted in yellow) is not grey'd out, you have sick constraints.

 

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Message 14 of 14
andrewiv
in reply to: ian.culhane

I have noticed that flexible sub-assemblies can cause this when placed into larger assemblies.  Not all the time, but have had it happen and when I turn flexible off the parts behave as expected.

Andrew In’t Veld
CAD Administrator

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