topic Re: Would you like to use flexible assemblies? in Inventor Forum

Would you like to use flexible assemblies?

Anonymous — Tue, 08 Dec 2015 07:56:33 GMT

Hllo All,

I am struggling with flexible assemblies for years. They are not usable and Autodesk is aware of that.

Lately I was informed that:

"There is no major effort right now to re-work the flexible assembly capability"

and

"If many users were asking for a way to make this flex assy modeling easier ..., it would be higher on the list."

So if you would like to be able to use flexible assemblies please send e-mail or inform Autodesk so they feel "many users are asking for it".

Please also add your post to this thread.

Cris.

Re: Would you like to use flexible assemblies?

-niels- — Tue, 08 Dec 2015 08:15:08 GMT

I'd say promote your idea some more:
http://forums.autodesk.com/t5/inventor-ideastation/fix-flexible-assemblies/idi-p/5562283

I did add a vote, so now it's hoping more people do...

Re: Would you like to use flexible assemblies?

CADMonkey4Life — Tue, 08 Dec 2015 09:21:04 GMT

So what's the problem?

Re: Would you like to use flexible assemblies?

Anonymous — Tue, 08 Dec 2015 09:57:39 GMT

Problem is that flexible assemblies are not usable at all. All they do is cause assemblies to crash and Autodesk is not interested in fixing this.

Here you have comprehensive description how the problem look like.

http://forums.autodesk.com/t5/inventor-general-discussion/flexible-nightmare/m-p/5514888#M537216

Cris.

Re: Would you like to use flexible assemblies?

WHolzwarth — Tue, 08 Dec 2015 12:34:35 GMT

I've made an attempt for myself with your dataset, and could fix it temporarily. I'll attach the files in your main thread.

But I've seen constraints become bad in many cases with flexible sub-assys. You can get them back for another while by simply editing them without any change, and click Ok then.

But this shouldn't happen at all. I agree, that flexible sub-assys could be working better.

Walter

Re: Would you like to use flexible assemblies?

Anonymous — Wed, 09 Dec 2015 07:35:21 GMT

Hi,

@ wh

What you say is partially true.

If constrains only become sick with no particular reason it is, as you say possible to get them back on track just by simply editing but not editing sub assembly. I document this in number of posts and videos.

But if top level assembly will force, so called, flexible assembly in to position against its internal constrains, it is not longer possible to restore its proper state in any way. This is also documented in video and description.

In a situation when sub-assembly is forced in to position against its internal constrains it is not possible to repair it and only thing that can be done is to delete it.

This is basically why flexible assemblies are not usable. They often destroy top level assembly.

I have spend months documenting this and sending to Autodesk. Not all of what I have done is published on forum.

Cris.

Re: Would you like to use flexible assemblies?

smokes2998 — Thu, 17 Dec 2015 11:44:48 GMT

Flexiable assemblies work fine

if you do the following

Constrain everything but the item you want to move.This mean fasteners as well

Do not pattern anything within the assembly

Put a limit mate on the items you want to move.

Check that the assembly moves in the predicted manner.

If the main assembly locks ups due to the flexible subassmbly suppress and unsuppress the mates causing a issue

Make sure that the design doctor is not showing a red cross. When it does rebuild the mates.

Re: Would you like to use flexible assemblies?

Anonymous — Thu, 17 Dec 2015 12:42:14 GMT

@smokes2998"Flexible assemblies work fine"

No they do not. Even if all rules you give are obeyed (although if they are many of real life constructions can not be modeled) inventor still crashes.

Honestly speaking, I would not consider anything "working fine" when requiring such restrictions even if in suchcase it would behave properly.

Cris.

Re: Would you like to use flexible assemblies?

mcgyvr — Thu, 17 Dec 2015 13:20:12 GMT

I use flexible assemblies on occasion and haven't had any serious/unsurmountable problems..

I wouldn't consider it "not usable" at all..

Are there some issues.. a few..

The best thing you can do is provide a dataset (or 2) to them that clearly illustrates a problem and submit a trouble ticket and see what happens.. (which it seems you already may have)

If there is a true repeatable issue I'm sure they will try to address it.. (I'd hope)

Re: Would you like to use flexible assemblies?

Anonymous — Thu, 17 Dec 2015 14:18:50 GMT

@mcgyvr

"The best thing you can do is provide a dataset (or 2) to them that clearly illustrates a problem and submit a trouble ticket and see what happens"

Well I did exactly that. Actually few times. If you would like to find some please look in this thread:

http://forums.autodesk.com/t5/inventor-general-discussion/flexible-nightmare/m-p/5514888/highlight/true#M537216

But nothing really happend.

I only managed to get information I showed in first post.

Cris.

Re: Would you like to use flexible assemblies?

mcgyvr — Thu, 17 Dec 2015 14:30:35 GMT

@Anonymous wrote:

@mcgyvr

"The best thing you can do is provide a dataset (or 2) to them that clearly illustrates a problem and submit a trouble ticket and see what happens"

Well I did exactly that. Actually few times. If you would like to find some please look in this thread:

http://forums.autodesk.com/t5/inventor-general-discussion/flexible-nightmare/m-p/5514888/highlight/true#M537216

But nothing really happend.

I only managed to get information I showed in first post.

Cris.

Yeah... Too much in that post to read/look at/comprehend... My attention span can't handle it without falling asleep..

I was the first to respond and know that some of your problems are from multiple solutions still being possible (lack of explicit vectors,etc.. as I stated)..

You seemed to dismiss those potential issues and then I never came back to see what other proof/further findings you had...

Re: Would you like to use flexible assemblies?

Daniel248 — Thu, 17 Dec 2015 19:44:19 GMT

@Anonymous wrote:
Problem is that flexible assemblies are not usable at all. All they do is cause assemblies to crash and Autodesk is not interested in fixing this.

Here you have comprehensive description how the problem look like.

http://forums.autodesk.com/t5/inventor-general-discussion/flexible-nightmare/m-p/5514888#M537216

Cris.

Hi Cris,

Forgive me for not agreeing with you on this issue.

I’ve used flexible sub-assemblies for years now, in much more complex assemblies (like 6 hydraulic cylinders manipulating a 6 DOF payload, and much more...), and not been disappointed so far. It could be the case that you’ll need to learn more about how to use them to achieve the desired effect.

I’ve had a look at the example you posted in this thread, and noticed that you’ve used 3 instances of the same (flexible) assembly. My choice would have been to use 3 different flexible assemblies here (easily obtained by doing a ‘save copy as’on your original flexible sub-assembly).

Of course, if you use limits for your constraints, you’ll need to ensure that you stay within those limits wherever you use that flexible sub-assembly.

In my opinion, flexible assemblies behave as expected when used with controlling parameters – much better than when dragged with the mouse in the assembly environment.

I’ve posted a short video here for you (available for 5 days only) to see some flexible assemblies in action, if you’re not convinced.

In any case, on this issue, I think you could achieve far more by asking questions and reading the replies from the many good people in this Forum who are so kind in assisting freely, rather than ‘waving a big stick’ at Inventor for not doing exactly what you’re expecting it to do.

Re: Would you like to use flexible assemblies?

Anonymous — Fri, 18 Dec 2015 07:54:21 GMT

Hi guys,

I do not mind you do not agree with me. You can have your own opinion on how Inventor and Autodesk works.

I personally find flexible assemblies not working. I did much to find a way to make them do, but with no success.

I have tried mcgyvr suggestions and also suggestions of other users.

@mcgyvr

you write again about lack of explicit vectors. Please note that this vectors you say ware missing in fact have been defined properly, what was shown at that time.

Fact is that assembly in witch I have all components constrained only on top level works fine and if some of those components are moved to flexible assemblies and constrained in a very same way top level assembly stops to work properly.

Only this would be enough to say this solution is not working.

List of restrictions to be obeyed in order to make flexible assemblies to work properly, as you claim, is in any case to wide.

- No pattern,

- Every flexible sub assembly as a single instance.

Only those two I consider enough to say this is not working. If I have a set of 200 extension screws I do not see an option not to pattern them and not to use many instances of as single extension screw. (imagine I need to change something in it. This would require changing every copy). Not mentioning parts list.

So I accept you can be happy with flexible assemblies in inventor but I can not understand how this is possible.

Unfortunately I am currently busy and have no time to rework my flexible assemblies, but I will definitely get back to this.

Cris.

Re: Would you like to use flexible assemblies?

smokes2998 — Fri, 18 Dec 2015 11:36:34 GMT

Unfortunatly coming from Solidworks and Solidedge background, this is the only way you can get flexible assemblies to work.... Inventor is very limited in what it can do. Espically when your assemblies go up to 7000+ parts and sub assemblies you have to work this way or it is crash city.

Re: Would you like to use flexible assemblies?

Anonymous — Wed, 23 Dec 2015 13:42:40 GMT

Hi,

As said I got back to subject and recreated from scratch one of my previous examples.

I followed restrictions posted in this thread. So there are no constrain to origin planes. Components are grounded.

There are no patterns.

Here is a outcome:. As I expected after promising beginning top level assembly crashed at some point and is not possible to fix.

In attachment you have this assembly to play with.

This is a model of an actual formwork. I needed its model to show its kinematics and explain why it did collapse.

Constrains defined in this assembly follow its real design. with some simplifications, but preserving all actual DOFs.

In this assembly behaves exactly the same way if there are numerous instances of flexible components and each flexible prop is placed as an single instance of a copy of original one.

It is not shown on this video but during trying to constrain this props assembly was forced in to positions against its internal constrains (which was new to me because I was used to flexible components being forced in such positions but not top level components). This time it was that this vertical supporting threaded bar, that is constrained to axis of a hole, was forced out of it. What is even more surprising design doctor was indicating no error in such state. I wish I had recorded that.

If you are able to make it work I will be more than happy.

Cris.

Re: Would you like to use flexible assemblies?

Daniel248 — Wed, 23 Dec 2015 14:01:47 GMT

@Anonymous wrote:
....
If you are able to make it work I will be more than happy.
....
Cris.

I doubt that anyone could make it work without the main assembly and the missing parts:

pl 01.ipt
pl 02.ipt
pl 03.ipt
pl 04.ipt
nakretka.ipt
prop big_casing.iam
prop big rod.ipt
prop small rod.ipt
prop small_casing.iam

There could be more...

Do a 'Pack & Go' on your main assembly & re-post.

Re: Would you like to use flexible assemblies?

Anonymous — Mon, 28 Dec 2015 22:10:29 GMT

Hi,

I was sure I did use Pack & Go.

Probably checked out some option.

sorry for the inconvenience. Here are all files in two parts.

Cris.

Re: Would you like to use flexible assemblies?

Anonymous — Mon, 28 Dec 2015 22:10:59 GMT

Re: Would you like to use flexible assemblies?

smokes2998 — Tue, 29 Dec 2015 13:39:34 GMT

Cris the rams need a defined limit mate and everthing else should be fully contrained

Re: Would you like to use flexible assemblies?

WHolzwarth — Tue, 29 Dec 2015 17:34:17 GMT

I've tried it here from my side, without good results.

For looking deeper into it, I began a master sketch (2015 file), but I'm not sure, if the dimensions are ok. Perhaps you can place it over your IAM and make some changes. Especially the length of the red block matters, because it influences the needed length values of the driven dimensions.

I'm in doubt, that these dimensions can be set up independantly.

Walter