Community
Inventor Forum
Welcome to Autodesk’s Inventor Forums. Share your knowledge, ask questions, and explore popular Inventor topics.
cancel
Showing results for 
Show  only  | Search instead for 
Did you mean: 

Constraint Order

7 REPLIES 7
Reply
Message 1 of 8
sathersc23
881 Views, 7 Replies

Constraint Order

We have noticed here that we can vary the behavior of our assemblies by changing the order of constraints. We have not found any good rhyme or reason to the order we generate our constraints, but we do see that some assemblies are just inherently more stable than others.

 

We're generally pretty good about mating to primary axis, planes, and the centerpoint where possible, however, for suspensions it's not always practical.

 

Has anyone had any experience with the constraint solver, changing the order of constraints, and playing with how the solution changes? Any insight into the inner workings of the constraint solver would help us out greatly.

 

I'm currently drafting CAD standards, and want to add in a "this is the heirarchy thou shalt build your constraints in" section. We're going back and forth with our vendor saying our designers and workflow suck, and our designers with an average experience of 13-15 years saying the software is crap.

 

-Sam

Sam Sather
CAD Admin
Inventor 2014
Vault Pro 2014 SR: 1 SP: 1
Intel Xeon X5690 @ 3.47 GHz
48.0 GB Ram
Windows 7 x64
AMD FirePro V7900 - 8.830.5.6000

----------------------------

"We have not succeeded in answering all our problems. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things." - Earl C. Kelley
7 REPLIES 7
Message 2 of 8
ampster402
in reply to: sathersc23


@sathersc23 wrote:

I'm currently drafting CAD standards, and want to add in a "this is the heirarchy thou shalt build your constraints in" section.


I've seen that a few yrs ago working on a large assy, sometimes you've got to constrain one thing before you do another...

 

But I wouldn't carve it in stone stating "You have to constrain things according to what's laid out in the CAD Standards".

 

May as well tie everybodies left hand behind their back and tell them to produce 20% more volumn if you're going to do that.

 

Regarding your statement/s made by the ppl with 13+ yrs experience, what exactly did these people receive in the form of actual training?

 

Usually people who make those type of statements have little to no actual training other than what they've read in a book or blog online.

 

I could be wrong about the previous statement, but I don't consider the software that bad.

 

Message 3 of 8
JDMather
in reply to: sathersc23


@sathersc23 wrote:

.We're going back and forth with our vendor saying our designers and workflow suck, and our designers with an average experience of 13-15 years saying the software is crap.

 

-Sam


What is the working relationship?  Can they offer suggestions?

I think I would want to see examples of the datasets.

 

It might be worthwhile to hire a consultant to do some additional training if these experienced designers are having great difficulty.

 

I don't have any concrete suggestions but search here for Walt Jaquith's, House of Cards essay.


-----------------------------------------------------------------------------------------
Autodesk Inventor 2019 Certified Professional
Autodesk AutoCAD 2013 Certified Professional
Certified SolidWorks Professional


The CADWhisperer YouTube Channel


EESignature

Message 4 of 8
sathersc23
in reply to: ampster402

I find the software perfectly acceptable for many things.I'd be perfectly happy with it for a number of non-vehicle based models and products. It has some quirks for sure, but it has some features I've found that I wish all CAD programs had.

 

I'm not convinced the constraint solver is robust enough to handle the flexibilty we build into our suspension assemblies (but we're still sub 300 parts typically). Forcing a build order would give some additional stability to our suspensions. Exploding models and/or blown constraints are something we deal with on a regular basis, and it's gotten so bad it's "fix it as best as possible and shove it back out the door" rather than actually find and fix root causes.

 

The experience is typically from Parasolid products or in one case ProE. We also in all honesty could stand to throw out 30-40% of our CAD library from the designers we inhereted some just downright crappy models from.

Sam Sather
CAD Admin
Inventor 2014
Vault Pro 2014 SR: 1 SP: 1
Intel Xeon X5690 @ 3.47 GHz
48.0 GB Ram
Windows 7 x64
AMD FirePro V7900 - 8.830.5.6000

----------------------------

"We have not succeeded in answering all our problems. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things." - Earl C. Kelley
Message 5 of 8
sathersc23
in reply to: JDMather

"I don't have any concrete suggestions but search here for Walt Jaquith's, House of Cardsessay."

 

Unfortunately we're not even at a point where I'm concerned about the house of cards effect. Bad modeling practices will drive unpredictable assembly behavior, and our team is aware and works with this.

 

We have a lot of instances though where you will change a parameter (say suspension travel) and the model will fail giving an error. On a good day you just "tug" the model and it snaps into place... on bad days the model will perform some fantastic acrobatics.

 

We really should get a contract consultant to come in here for 6-12 months and work on improving our CAD practices, but I've come near the point on a few occasions where I've wanted to take 2 weeks, remodel every part from scratch, and prove out that using the software can be done and it's really our fault. Justifying that to management though is a tough sell.

Sam Sather
CAD Admin
Inventor 2014
Vault Pro 2014 SR: 1 SP: 1
Intel Xeon X5690 @ 3.47 GHz
48.0 GB Ram
Windows 7 x64
AMD FirePro V7900 - 8.830.5.6000

----------------------------

"We have not succeeded in answering all our problems. The answers we have found only serve to raise a whole set of new questions. In some ways we feel we are as confused as ever, but we believe we are confused on a higher level and about more important things." - Earl C. Kelley
Message 6 of 8
JDMather
in reply to: sathersc23

Somewhere I saw a document on robust assembly constraint theory.  I think it was for another SW, but the principles should be the same.

 

My general impression is that 90% of what I see (in Inventor, SolidWorks or Creo) is garbage.  And that is only becuase I actually have a history tree and can (usually) figure out where things went wrong (or at least poorly).  AutoCAD and other direct modeler stuff scares me no end.  I sometimes wonder how anything gets out the door and actually works.  I find myself analyzing bridges as I cross them, buildings as I walk through them, airplanes.... ....as  I enter the door I'm always tempted to ask the captian if he brought his A-game today.  But I can't begin to question the maintanance all the way back to manufacture and assembly....

I'll try to locate that document.


-----------------------------------------------------------------------------------------
Autodesk Inventor 2019 Certified Professional
Autodesk AutoCAD 2013 Certified Professional
Certified SolidWorks Professional


The CADWhisperer YouTube Channel


EESignature

Message 7 of 8

Just now saw this post from 1-1/2 years ago, because I was looking for answers to the same general problem.  I wonder if Autodesk would consider (for future versions, of course) creating a new object in the constraints hierarchy along the idea of a "constraint family", whereby its individual members (assembly constraints) could be prioritized with an integer (1, 2, 3,...).  I would certainly use it.  Anybody from Autodesk...where would I make such a request?

Larry Daubenspeck
Software Programmer
Draper, Inc.
Message 8 of 8


@larry.daubenspeck wrote:

...where would I make such a request?


http://forums.autodesk.com/t5/Inventor-IdeaStation/idb-p/v1232


-----------------------------------------------------------------------------------------
Autodesk Inventor 2019 Certified Professional
Autodesk AutoCAD 2013 Certified Professional
Certified SolidWorks Professional


The CADWhisperer YouTube Channel


EESignature

Can't find what you're looking for? Ask the community or share your knowledge.

Post to forums  

Autodesk Design & Make Report