Top Down IPT Assembly Error - Is Inventor lagging behind usage?

[CJ.10E-10mm]

Help Please!

I have a top down assembly of 45 parts with just short of 200 sketches.

I am getting a cyclical dependency error without any hint as to which part or sketch is involved.

Traditionally Inventor .ipt files were intended for the modelling of a single componenet but of late top-down assembly modelling has come to the forefront.

Thus in my case, short of endeavouring to move my end of part marker back up through the relevant sketches I have absolutely no idea which sketch or part is at fault.

Has anyone any meaningful advice please?

Many thanks.

CJ

[JDMather]

If you are going to use top-down rather than multi-body solids and you run into a problem like this you have two choices:

1. Go through the assembly yourself to find the problem, learning from the process so that the problem can be avoided on future projects, or

2. Attach your assembly here so that someone else can go through the assembly yourself to find the problem and inform you of the source so that the problem can be avoided on future projects.

(or 3rd choose, have someone where you work do process #2).

[CJ.10E-10mm]

Thank you.

CJ

[CJ.10E-10mm]

The point I was endeavouring to make is that whilst others more capable than myself have extolled the virtues of Top Down multi-part modelling it would seem that the software has not been adjusted accordingly to accommodate the process.

The cyclical error warning would surely not be relevant in a single part model and thus one would hope that in the fullness of time the AutoCAD development team will enable such an error to be treated in a similar manner to a Constraint Error; in that it would identify the parts concerned.

I am of course most grateful to JD Mather for taking the trouble to reply but in the light of no other comment I am obliged to assume that Top Down modelling is viewed as somewhat undesirable, whereas I have found it has its distinct advantages; albeit I stumbled into the process initially by accident.

CJ

[JDMather]

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@CJ.10E-10mm wrote:

Traditionally Inventor .ipt files were intended for the modelling of a single componenet but of late top-down assembly modelling has come to the forefront. 

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There are tutorials here http://www.mcadforums.com on top-down modelling going back many years. 

I attended classes at http://au.autodesk.com on top-down modeling in Inventor many years ago.

I don't think this is a "new" idea in any way.

Users like Sean Dotson have been demonstrating this technique as far back as I can remember.

Walt Jaquith has some comments relative to the process (or any Inventor technique) in this thread

http://forums.autodesk.com/t5/Autodesk-Inventor/IS-INVENTOR-REALLY-USEFUL/m-p/1332811/highlight/true...

(see post #8)

You wrote, "Please Help", but I don't think anyone can really help without seeing a representative dataset.

If it is not really "help" you want with a particular problem, then maybe this forum http://forums.autodesk.com/t5/Inventor-IdeaStation/idb-p/v1232

is where you should post an idea for a "general solution" to all problems of the type you describe.

[CJ.10E-10mm]

Dear JDMather,

I apologise if I have, for whatever reason, irritated you for that was not my intention.

I am developing a new form of advanced medical equipment in conjunction with my scientist colleagues at the MoD in the UK. As you can imagine it would not be appropriate to publish on an open forum highly sensitive information.

I am nevertheless, as previously stated most grateful, for all assistance obtained on the forum including that from your good-self.

If top down modelling is as ’old as the hills’ as you have explained, it would seem that the AutoCAD development team have not considered it merited developing the software’s capability to cater for it fully which, from my, albeit perhaps naive perspective at least, is somewhat sad.

CJ

[Hochenauer · Accepted solution]

I added your request to the idea station:

http://forums.autodesk.com/t5/Inventor-IdeaStation/I-want-better-error-reporting-when-a-cyclical-con...

Please feel free to add additional information to help others understand and vote for this project. We use this system to rank requests and make sure to spend our development resources in alignment with our customers needs.

Thanks!

Gerald

[JDMather]

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@CJ.10E-10mm wrote:

..it would seem that the AutoCAD development team have not considered it merited developing the software’s capability to cater for it fully which, from my, albeit perhaps naive perspective at least, is somewhat sad.

CJ

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This is the Autodesk Inventor forum.

The AutoCAD forum is over here http://forums.autodesk.com/t5/AutoCAD-2013-2014/bd-p/706

[CJ.10E-10mm]

Dear Hochhenauer,

Thank you, I am most grateful.

I am also grateful that you did not get ovelry touchy at my term AutoCAD when I suppose I should by rights have used Autodesk and / or Inventor. I had not realised that the forum is quite so territorial!

You will appreciate that I am a relative novice of Inventor and any meaningful assistance is truly appreciated.

Thank you once again.

CJ

[Hochenauer]

You are welcome CJ.

[ic198]

I have on a few occasions had the 'cyclical constraint' error message appear when there was no cyclical error. Usually this has happened when the EOP is midway through a complex part. Try forcing the EOP to the end of the model (right click on the EOP, move EOP to End). You might also try a Rebuild All, on the Manage tab.

I have never been able to recreate this error dependably enough to report it, though my software supplier has said he's heard of similar cases.

[CJ.10E-10mm]

Dear ic198,

Thank you for your kind, intelligible observations based on your own personal experience.

It is frustrating when one comes up against what appear to be obvious gremlins within the software and are not taken seriously by those that should know better.

Thank you once again for taking the time and trouble to respond.

I was beginning to think I had two heads prior to your observations.

cj

[Hochenauer]

If anybody has a dataset with a workflow consistently showing this behavior, please let us know. It is difficult to fix these kind of issues without a reproducible workflow. 

You can email such a case to "johnson dot shiue at autodesk dot com"  or to myself "gerald dot hochenauer at autodesk dot com".

Thanks for your patience and help to make Inventor better.

regards,

Gerald

[ic198]

Hi Gerald,

I had a vague memory of reporting something similar to this before, so I checked my emails and found I'd had a discussion with Chris Mitchell at Autodesk back in April 2013 about cyclical constraint issues. I did send a dataset to him. He advised me to install SP1.1 update 2 and afterwards do a Rebuild All on the part. I think that fixed the problem then. Might be worth you contacting Chris?

I have very occasionally had the same problem since but using the fixes described in my previous post I've usually managed to get rid of the message. If I come across the problem again I'll let you know.