Inventor General Discussion

Inventor General Discussion

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*Expert Elite*
mrattray
Posts: 2,538
Registered: ‎09-13-2011
Message 1 of 8 (336 Views)

Sketch changes constrain status after rebuild

336 Views, 7 Replies
10-22-2012 11:28 AM

I have a sketch that Inventor changes its status between under constrained, over constrained, and fully constrained depending on dimensions (makes sense), and wether I rebuild the model (WTF?).

 

Steps to reproduce:

1) Open the attached .ipt file.

2) Examine Sketch11 (under Face3) It should be fully constrained.

3) Exit the sketch. Open the parameters dialog and change the value of "angle" from 45 to 60. (If you get an error message change it to 50 first, then 60. It's a work in progress.)

4) Re-examine Sketch11. It is now under constrained.

5) Exit the skecth and go to the manage tab. Click "Rebuild All".

6) Re-examine Sketch11. It is now fully constrained.

7) Scratch your head and post back with your theory.

 

Thanks in advance!

Mike (not Matt) Rattray

*Expert Elite*
mrattray
Posts: 2,538
Registered: ‎09-13-2011
Message 2 of 8 (333 Views)

Re: Sketch changes constrain status after rebuild

10-22-2012 11:39 AM in reply to: mrattray

OK, Inventor must be on drugs.

 

Before:

Capture.JPG

 

 

After I delete the driven 98deg angular dimension (no other change):

Capture2.JPG

Mike (not Matt) Rattray

*Expert Elite*
mrattray
Posts: 2,538
Registered: ‎09-13-2011
Message 3 of 8 (327 Views)

Re: Sketch changes constrain status after rebuild

10-22-2012 12:30 PM in reply to: mrattray

Now I've found that I can change this radius by dragging but I can't dimension it!  What the hell drugs is Inventor on today?!

 

Capture.JPG

Mike (not Matt) Rattray

Employee
NicolasXu
Posts: 176
Registered: ‎10-24-2008
Message 4 of 8 (308 Views)

Re: Sketch changes constrain status after rebuild

10-22-2012 08:33 PM in reply to: mrattray

Hi Mike,

 

There are some problems in the Sketch somehow. It’s not fully constrained in deed, but Inventor reported it as fully constrained. I will report it to development team for a further look. (I also re-drew the sketch based on the existing dimension and constraints, it's under constrained. Attached here for your reference.)

 

If you delete one driven dimension - arc length dimension on top arc, you will find the sketch is under constrained.

 

To fix the problem, you can follow the next steps:

  1. First delete the arc length dimension on top arc.
  2. Then make the driven dimension d110=75 deg as driving dimension.
  3. Finally add the arc length dimension back as driven dimension
  4. Now you can change the "angle" parameter from 45 to 60 without error.

Thanks,



Nicolas Xu
Sr. SQA Eng.
Fusion 360 Quality Assurance Team
Autodesk, Inc.
*Expert Elite*
mrattray
Posts: 2,538
Registered: ‎09-13-2011
Message 5 of 8 (290 Views)

Re: Sketch changes constrain status after rebuild

10-23-2012 05:20 AM in reply to: NicolasXu

Thanks for looking into this for me, Nicolas. Could it have anything to do with the arc length dimension being referenced in both/either a pattern definition and an iLogic rule within that part? It seems like there's been a change to the way that calculations involving reference parameters are resolved in one of the SPs. It used to be that a update-rebuild-update sequence had to be used to resolve these calculations in the past, but it seems that this is no longer necessary.

Mike (not Matt) Rattray

*Expert Elite*
mrattray
Posts: 2,538
Registered: ‎09-13-2011
Message 6 of 8 (285 Views)

Re: Sketch changes constrain status after rebuild

10-23-2012 05:47 AM in reply to: mrattray

Before:

Capture.JPG

 

After deleting arc length:

Capture2.JPG

Mike (not Matt) Rattray

Employee
NicolasXu
Posts: 176
Registered: ‎10-24-2008
Message 7 of 8 (257 Views)

Re: Sketch changes constrain status after rebuild

10-23-2012 08:42 PM in reply to: mrattray

Hi Mike,

 

Deleting the driven dimension is just an approach to show that the sketch is actually under constrained, and a way to force the recalculation of constraints. We can also delete & recreate some constraints to trigger the calculation (This way should work for the last 2 screenshot you attached, which looks different with the attached part in post #1).

 

To figure out the root cause, we may have to know how the “sick” sketch was generated, is it created from scratch or included in a template?

 

If it’s in a template, you can fix it by triggering the re-calculation. If not, would you share more information about the workflow (iLogic rules, etc. I didn't find a iLogic rule referring to model parameters in your attached part)? You can email me details if needed. (lixiongDOTxuATautodeskDOTcom)

 

Thanks,



Nicolas Xu
Sr. SQA Eng.
Fusion 360 Quality Assurance Team
Autodesk, Inc.
*Expert Elite*
mrattray
Posts: 2,538
Registered: ‎09-13-2011
Message 8 of 8 (226 Views)

Re: Sketch changes constrain status after rebuild

10-24-2012 06:34 AM in reply to: NicolasXu

Hi Nicolas,

I have the sketch working now the way I want.

So, does Inventor only do a partial calculation on dimensional changes and some sort of other more thorough "sketch rebuild" on larger changes like deleting a dimension or constraint?

I drew this sketch from scratch; the rules are from the template but only control sheetmetal styles, patslist properties, etc.

The parameter "angle" is the driving value for the shape of the part. The value of "angle" is written by an iLogic rule from the assembly, but there was no other programming afecting the parameters of the sketch in the part that was posted.

Let me know if you have any more questions, I'd like to try and get this wierdness figured out.

Mike (not Matt) Rattray

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