suppressed constraints are automatically unsuppressed

[Anonymous]

Hi All,

I have an assembly (let's call it guide.iam) in which i use positional representations to show the limit positions of a carriage running on a guide. I use suppression in the positional representations, and this normally works fine. So basically:

- position 1: constraint 1 enabled, constraint 2 suppressed

- position 2: constraint 1 suppressed, constraint 2 enabled.

In the master representation i suprpess one of the constraints so they don't conflict. This all works just fine.

But,

I have placed the guide.iam assembly into another assembly, and even if i did not edit or modify guide.iam it sometimes spontaneously yields a mating error. Checking the design doctor then shows there is an issue with the constraint that was suppressed in the master positional representation. If i now open guide.iam to investigate, the constraint is suddenly unsuppressed. Note that i did not modify the assembly, nor did i change any representation, not did i make the guide.iam flexible in the top level assembly or anything. I did not touch it. At all.

How is this happening? Does Inventor unsuppress constraints when updating or something?

Any help would be appriciated here. Thanks.

Misha

[johnsonshiue]

Hi Misha,

The behavior sounds like a bug to me. Another is probably the PosRep contains contradicting overrides. If possible, please share the files here so forum experts can take a look. Or, you can send the files to me directly ([email protected]). I would like to understand the behavior better.

Many thanks!

[AJK2010]

Hey, we have the same problem, the suppressed constraints in the master representation in a sub-assembly are un-suppressed after switching positional representations in top level assembly. 

[johnsonshiue]

Hi! Please share the files here or send them (zipped) to me directly [email protected]. I would like to understand the behavior better.

Many thanks!

[AJK2010]

Hey,

we are a bit sceptical for sharing our files,

but i made a screen capture of the behavior.

I hope that this wil be fixed in a new update.

We now use inventor 2020 Build: 373 Release: 2020.3

[johnsonshiue]

Hi! I have a few theories about why it behaves this way. But, I do need to see the files in order to suggest next logical step. The behavior is wrong. I think it is a bug. But, I want to know how to make it work and also, if it works in 2021 correctly.

Regarding sharing files, we deal with various levels of data security. We do not share any file in public unless you explicitly agree to. Within the company, you can specify who can access your data from where. I can sign NDA if need be. Or, you can sign up Inventor Feedback Community (https://autode.sk/InventorBeta), where the mutual NDA is included in the usage agreement.

Many thanks!

[AJK2010]

I have sent you an email with a link to the files.

[johnsonshiue]

Hi! Many thanks for sharing the files with me! You can unshare it now. Like I replied to you in the email, this is indeed a bug in Flexible/PosRep workflow. As you can see on the forum, we do have quite a few Flexible/PosRep issues. Your case is related to a problem that activating a non-Master PosRep in a flexible subassembly when master PosRep is active at the top-level. The only workaround I can think of is to create individual PosReps at the top and each correspond to a non-Master PosRep subassemblies. Avoid activate non-Master PosRep in the subassembly while you are at the top-level.

Fortunately, the issues have been resolved as of Inventor 2021. If you have access to 2021, please try it out and see if it works better. I am sorry that the fixes on 2021 cannot be ported backward unfortunately.

Many thanks!