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Can we design Multi Body Part../?

dbodar
1-Newbie

Can we design Multi Body Part../?

Hello,

I want to design Mouse in creo, i done outer body using surface..

Now I want to divide in multi part.. Its possible in Creo..?

If yesh then how can we do it..?

Same thing can do in SolidWorks,

its work on multi body part modeling base, so...


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1 ACCEPTED SOLUTION

Accepted Solutions
mbonka
15-Moonstone
(To:dbodar)

Hello,

perhaps you are asking about skeleton technique and TOP-DOWN design. The target is share driven geometry from one "main part" to all anothers?

Try to search more information about copy geometry.

For example youtube offers some tutorials:

Top Down Design using Skeleton Assemblies - Part 4 - External Copy Geom - YouTube

Regards

Milan

View solution in original post

20 REPLIES 20
mbonka
15-Moonstone
(To:dbodar)

Hello,

perhaps you are asking about skeleton technique and TOP-DOWN design. The target is share driven geometry from one "main part" to all anothers?

Try to search more information about copy geometry.

For example youtube offers some tutorials:

Top Down Design using Skeleton Assemblies - Part 4 - External Copy Geom - YouTube

Regards

Milan

View solution in original post

dbodar
1-Newbie
(To:mbonka)

Thanks for this..

but this not what i want to know..

DeanLong
10-Marble
(To:dbodar)

Deapk,

Creo is not a "multi-body" type software like NX, Catia etc.... Although what you want to do is possible with a Top Down method and can be accomplished by a few methods. You can use a Master/Merge, Publish Geom/CopyGeom or you can use an Inheritance feature. You could do it as a Bottom Up method but it is not advisable since you have an exterior, countered surface that is shared by multiple parts.

I prefer the PubGeom method. In any case, you can create all the part break outs in one file and then "share" the information to the individual parts as one or multiple features. If you need to see a simple example, let me know.

Dean

dgschaefer
21-Topaz II
(To:dbodar)

Creo does not allow for multiple solid bodies within a single part like SW does.  You can make multiple, non-overlapping solids in a single part file, but Creo treats them as one.  If they overlap, they are merged.  Each part of your mouse should be a separate part file.  It's slightly more cumbersome, but I find it to better represent the reality of the physical product.

The top down design techniques mentioned above can be used to pull the surfaces out of the master model you've created into the individual parts.  I find the skeletons & publish geom / copy geom pairs to be the most robust and flexible, but it does require the Advanced Assembly Extenion (AAX) which you may not have.

--
Doug Schaefer | Experienced Mechanical Design Engineer
LinkedIn

Just wanted to confirm that what Doug and Dean are talking about is the way to go in Creo. Create a master model which is like a layout of the old days and then use those surfaces and any thing critical shared between parts using one of many techniques. I prefer using Publish Geometry out from the master and copy geometry from the master to import into the individual shapes. It can seem like extra work up front, but will totally be worth it down the road especially if you create the master thinking about association between features and geometry. Make changes in the master and regenerate the master and parts and get all the changes down steam. This can be a very robust modeling technique. Good luck.

bgruman
1-Newbie
(To:dbodar)

Building on Dean, Doug, and Mark...

I will also throw in my vote for the Master Model - External Copy Geom technique.   I personally use this technique every day.  There is no way I could do what I do with the quality and proper matchup between complex piece parts without this powerful tool.

Good Luck

Bernie

Bernie Gruman

Owner / Designer / Builder

www.GrumanCreations.com

 

Hello,

I have worked several years with CATIA V5 . We had a "Basic Feature" method only works with multibody . Instead of multibody I use in CREO closed quilts . The quilts are then used by Solidifys. Analogous to the Boolean operations in CATIA V5 . In addition, I also use the top-down methodology with EXTERNAL COPY GEOMS and PUBLISH GEOMS.

 

mwodarz_INNEO
13-Aquamarine
(To:dbodar)

PTC Strategy is: one part, one material, one mass -> just like in real / physical world.

BUT - you can simulate similar things just like in SWX with little restrictions

First thing:

- you need discipline in managing features in your model tree

then you can use closed quilts instead of solids.

- manage the features for each quilt in right order in the model tree

- use annotations features (without annotations) as marks to sort your features

- use an analyze feature with the right density for each quilt to calculate the complete mass of your multi body part

- separating the visibility with layers would be very helpful - even when you use combined states

So: If you can work with this restrictions, you can create multi body like parts - IMHO - I never used multi bodies in SWX, 'cause I can't see the benefit. The PTC strategy works fine and goes 1:1 like real world.

But you can do with your system, whatever you want.

(Presales) Senior Technical Consultant @ INNEO Solutions GmbH (Germany)

Marco,

What you have described is essentially a Top Down approach, normally utilized in an Assembly with one of the procedures described above. Managing all the surfaces, merges, quilts can get a bit tedious, essentially if you are referencing offset surfaces (I.E. body gaps, reveal lines, etc... with merges) With a single change it can go pear shaped quickly.

Am I reading correctly you do this in a .PRT file? IMHO, I believe you are making more work for yourself in the long run.


It's true - this technique makes more work with some restrictions. And I can't see the benefit inside Creo. So I prefer a clear top-down-solution with skeleton, publish and copy geom with clear downstream and replace options. But not everybody have an essentials team or advanced assembly license.

And what I'm doing with Creo is always playing. I'm not paid to build up CAD data. I use it for fun.

(Presales) Senior Technical Consultant @ INNEO Solutions GmbH (Germany)


That's fair. I forget not everyone will have all the license capability. But, even with simple Assembly Mode you can get the results without all the extra surface work and management. Both methods work....just depends how much "Fun" one wants to have, I guess.

Cheers.

Anonymous
Not applicable
(To:dbodar)

Not seen anything for multi-body. Would be useful. However I have devised a work around by using an assemby of a part and tracing the relevent geometry into the new part and then drop the references PDQ as the next time you load up the part as stand alone all the references would not be there and the whole lot will crash. Sorry PTC but Solid Edge wins here again with the syncronous technology, multi-body modelling, automomous re-referencing, again and again, time is saved in bucket loads.

Francis,

Multi body is really a "what one is used to doing" type thing. I have worked on both types of software and, IMHO, one does not have an advantage "technically" over the other. Each method gives the same results, with the same amount of control as the other.


Anonymous
Not applicable
(To:DeanLong)

Dean

Thanks for your views. I too have used both types. I just get on better with the direct, nudge to surface, lock to feature that SE provides, I just find it so more fluid and much quicker to use than traditional ordered, parametric modelling where topology can mean that the thing that you want to reference from is often just not there without the extra operations of setting up a special reference plain higher up in the tree along with another sketch at the top with all the references detached, so you can lock onto things, but that can most of the time get out of date rather quickly too.

 

... Sorry PTC but Solid Edge wins here again with the syncronous technology, multi-body modelling, automomous re-referencing, again and again, time is saved in bucket loads.

I'll strongly disagree with that statement. We have both SE & Creo here (and SW too for that matter). Our team will take skeleton driven top down design in Creo every time, especially if we have to move fast,  In the past 24 months, our team of 6-8 engineers have brought 6 complex consumer products from concept to tooling release because of the TDD techniques available in Creo.  No way we could have gotten there with SE or SW.  That is in part due to what we are familiar with, but we haven't seen anything in SE that looks even close to the power. We know SW quite well and the tools simply don't exist there.

--
Doug Schaefer | Experienced Mechanical Design Engineer
LinkedIn
Anonymous
Not applicable
(To:dgschaefer)

Hi Doug

Im open and always interested to see different ways to do things. Which parts of Creo you are using to do your "skeleton driven top down design" would very much like to see some video samples, possibly on youtube, maybee.... I do not know everything and your comments interest me a lot.

Kind regards

Francis

It's not a single technique, but rather a system of modeling techniques that work together. The core of it is:

  • Using skeletons to define the design intent
  • Creating Publish Geometries in the skeleton to define sets of geometry to pass on to the parts or sub assys
  • Creating External Copy Geometries in the parts and sub assy skeletons to retrieve the data
  • Careful, intentional reference selection that explicitly capture your design intent

A skeleton is a special part that is used to define your overall product's design intent.  It has to be created in the context of an assy and you have to have the advanced assembly extension.  The top level assy skeleton contains the geometry needed to be shared at that level.  The main outside shape and major fastening or motion items, for example.  Each sub-assy has it's own skeleton that contains more detailed information that needs to be shared between the parts in that sub assy.  Depending on the complexity of the entire product, we typically only go 1 or 2 levels down with sub assy skeletons to keep things more manageable.

In the skeletons, we create a publish geometry feature for each part or sub assy that contains the geometry that item needs.  A publish geom is like a bucket you put a set of geometry in for passing on to another part.  In the sub assy skeletons and the parts, we create an external copy geometry that references that publish geometry, pulling the relevant skeleton model data in.  It's like reaching in that bucket and pulling that geometry into that part.

In most cases, we use the default CS for both assembling the component and locating the external copy geom. In cases where default assy position doesn't make sense for a given component (the origin of the assy would be far outside the envelope of the part, for example), we create a CS for that component in the skeleton and use that CS both for assembling it and for the external copy geom.  It's important that the assy CS and the external copy geom CS match.

We make very heavy use of the skeleton, putting in geometry for every instance where two parts or sub assys need to share geometry. Everything from the outside shape, parting lines and major mechanism features like pivots down to screw boss locations and heights go into our skeletons.  Again, if it's shared geometry, it goes into the skeleton.  Some will say keep them simpler, but we've had great success with our method.

A major consideration, however, has little to do with the actual TDD technique and more to do with the modeling and creation of individual features. If you are careful with reference selection and model to capture your design intent, you will be rewarded with very robust and very responsive models.  Think as if you are baking your design intent into your feature construction. 

We've been able to make major size changes to overall dimensions of very mature assemblies (in some cases live in a client meeting!) with very few feature failures.  It's quite satisfying to change an early skeleton feature effecting 6 or 8 parts, regen your 3800 feature assy and have no failures.  Make the whole product an inch shorter and still release for tooling on Tuesday? No problem.

There are some good KB articles on skeleton modeling, search for them.  I cannot link to them because my company's maintenance agreement has expired.  I searched a bit for videos, but didn't find any that show exactly what we are doing, but there are some out there that show the basics of creating a skeleton and creating publish & copy geometry features.  Part of the problem is that it's very specific to your design. Learn the basic techniques and you can then apply it to what you do.

That's an intro (there's a lot more) but I hope that helps.

--
Doug Schaefer | Experienced Mechanical Design Engineer
LinkedIn
Anonymous
Not applicable
(To:dgschaefer)

Hi Doug

Thank you so much for your introduction, most interesting. I will have to read it a few times to get into that mindset of assembly Skeleton control. This actually reminds me of a top down way of working that I have found very sucessful particularly with boundry surface modelling, where I have a control sketch at the top of the tree that everything relates back to it via referencing. From that I have used these reference dimensions and entered these into Family Tables for the vairable factors that create the instances. I have had a look on youtube on the advanced assembly module and have found something that I will need to see a few times by Leo Greene from ECogintion that includes the use of skeleton control modelling system. I have also found a useful bit of detail on intent selection, that could help provide a more stable model, all very interesting. I understand the feeling when whole assemblies update, reject unwanted sub-family table assemblies and end up with a complete machine at the end. I feel that I might be able to apply your setup into my family table setup and create something really more spectacular than I already have.

Regards

Francis

dbodar
1-Newbie
(To:dbodar)

Thanks to all of you...

I got the answer from your discussion...

and also learn something new from these all discussion...

In short, if we want multi body modeling, then Skeleton and Published Geo are the best option... and from this we can solve all the problems.....

mbonka
15-Moonstone
(To:dbodar)

Hello,

please mark correct answer in order to help other users in future...

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