topic Re: Flexible chain, not driven in Inventor Forum

Flexible chain, not driven

Anonymous — Fri, 12 Feb 2016 13:18:24 GMT

I am trying to make a drag chain that is flexible, but not driven. Every example I see says you have to make it adaptive and drive it.

I do not want it adaptive, nor driven. They are just fixing it in place until you tell it to move a bit, slowly...

When I model it piece by piece, it is ok for the first two links. Then after that, it starts jittering about that place like it's having a fit. Then the programme crashes

I can't believe drawing packages are still limited to this 'animation' style of movement. It's not practicle, not particularly easy to use driven contraints. I need to know how things are affected in a variety of different movements.

Is it possible to make a cable/drag chain. It's only got to move through two planes. The length is constant. It's got axes (plural of axis, not a death wielding machine)....

Re: Flexible chain, not driven

PaulMunford — Fri, 12 Feb 2016 19:11:56 GMT

Have you tried using angle constraints with limits set?

Re: Flexible chain, not driven

admaiora — Fri, 12 Feb 2016 21:41:47 GMT

To many constraints..you could have problem for them..

Betreff: Flexible chain, not driven

WHolzwarth — Fri, 12 Feb 2016 22:00:13 GMT

Hmm, ok. I didn't do it.

But I saved it. Inventor 2014 and earlier files in Zip. Move it by angle driveme of counter.ipt.

Walter

Betreff: Flexible chain, not driven

Anonymous — Mon, 15 Feb 2016 09:15:10 GMT

@WHolzwarth wrote:
Hmm, ok. I didn't do it.
But I saved it. Inventor 2014 and earlier files in Zip. Move it by angle driveme of counter.ipt.

Walter

I am using 2013, but I cannot open it...

What I would suggest Inventor needs, is a 'curtain rail' style contraint. Where an object can be contrained to a open or closed guide, on any angle. I am not sure how complicated the equations would be, but as long as it has fixed parameters (such as direction of travel, and angle from the curve), the freedom of movement would be simple...

Betreff: Flexible chain, not driven

Anonymous — Mon, 15 Feb 2016 09:19:39 GMT

Could you use blocks? I remember in my training there were blocks you could move, and they were much simpler

Betreff: Flexible chain, not driven

Anonymous — Wed, 17 Feb 2016 14:59:57 GMT

Hi,

Could you pos, or upload your model?

I would like to give it a try.

Cris.

Betreff: Flexible chain, not driven

Anonymous — Wed, 17 Feb 2016 15:14:43 GMT

You're more than weclcome too. I spent a while trying to get it working right, but the constraints just made it jitter all over the place.

Remember, it has to be in a flexible state, and not driven.

Thanks

Re: Flexible chain, not driven

Ray_Feiler — Wed, 17 Feb 2016 15:27:29 GMT

Something like this maybe? Just open it and drag it or insert it into your assembly and make it flexible. It is not perfect mind you.

Re: Flexible chain, not driven

Anonymous — Wed, 17 Feb 2016 15:50:07 GMT

That's pretty good. I am liking this. However, there was an error. The cable had turned over on itself

You can see that quite a few links have fallen back. NEvertheless, it is definately in the correct direction

Re: Flexible chain, not driven

Anonymous — Wed, 17 Feb 2016 15:54:03 GMT

Just watching the movement. Maybe adding two axes instead of just one may stop the chain from twisting into itself?

Re: Flexible chain, not driven

Anonymous — Wed, 17 Feb 2016 16:04:20 GMT

I used it once, and this happened.

Have you used this in an assembly?

Re: Flexible chain, not driven

Ray_Feiler — Wed, 17 Feb 2016 16:29:14 GMT

No, I gave up on it.

Re: Flexible chain, not driven

Anonymous — Wed, 17 Feb 2016 17:05:21 GMT

I don't balme you. I think this is a lost cause until Inventor development team can create better flexible restraints. Even linear numerical (e.g. axis 1 is x distance from axis 2, but no closer than y from 3). Or a bendy constraint, where you can restraint a part, but it has a bit of flex to it.

Either way, the current method of 'adaptivity' for a chain is about as advanced as when I was at college, many years ago.

Re: Flexible chain, not driven

Ray_Feiler — Wed, 17 Feb 2016 18:30:07 GMT

I did this in March of 2015 using Inventor 2012. As I'm studying it again I notice if I edit any of the transitional constraints I can not see there inputs. Is that normal?

Re: Flexible chain, not driven

Anonymous — Thu, 18 Feb 2016 12:32:39 GMT

@Anonymous

Hi,

You must know that if you try to use it as flexible component it will crash at some point.

You can visit this threads that are just about flexibility causing problems:

flexible nightmare

would you like to use flexible assemblies?

in case you agree that flexible assemblies do not work as they should, here you can support idea to fix them: Fix Flexible assemblies

As for your model I have downloaded it and will make an attempt, probably during weekend.

Cris.

Re: Flexible chain, not driven

Anonymous — Thu, 18 Feb 2016 13:12:25 GMT

If I didn't know they crashed before, I do now!

The whole notion of flexible parts is essential in design. So many times I have been held back from modelling something properly because of this issue. It's like nothing has improved in the past 10-15 years!

If you get it working, I shall be grateful, but I shall not hold my breath. I don't think Inventor is ready for this sort of modelling without an immense level of processing power.

We have 4 drag chains 1 in a sub-assembly, and 3 in the main model. I bet just to get it to move will make my computer wince

Re: Flexible chain, not driven

Ray_Feiler — Thu, 18 Feb 2016 14:41:35 GMT

If I open my assembly in Inventor 2012 I can see the transitional constraint inputs but in 2016 it is as if they don't exist but somehow they still seem to work. Also if I edit the constraint in 2016 and make new selections or create a new transitional constraint and try to edit it, the inputs seem to disappear and both input selections are available. Is this as designed behavior in 2016?

Re: Flexible chain, not driven

Anonymous — Fri, 19 Feb 2016 08:42:39 GMT

@Anonymous

See if this is roughtly how this chain works.

Assemblies I attached use your parts with no changes. (for some reason I cannot post zip)

Cris.

Re: Flexible chain, not driven

Anonymous — Fri, 19 Feb 2016 09:26:54 GMT

Thanks for having a go Cris, but this is pretty much how far I got. As you can see in the middle of your video, the arm does not move as expected. It jitters and moves in random directions.

It's a good effort, but I can see this just going wrong within a few times of use.