Top Down Design - MULTI-BODY PART MODELING

[aurel_e]

I consider it the best  technique for a stable assembly especially when I know I might need to change it many times (position of holes slots etc.).

Do you use it or you consider it something to avoid.

[aurel_e]

I consider it the best  technique for a stable assembly especially when I know I might need to change it many times (position of holes slots etc.).

Do you use it or you consider it something to avoid.

[Cadmanto]

Are you asking for the combination of both in the same model?  Top Down and Multi-body parts?

Personally, I use multi-body parts only when I have a purchased part that is an assembly.  Easier for me to just have one part file representing multiple parts then an assembly.

Top down I use once in a while for reverse engineering or when I have a lot of parts that are dependent on each other.

Hope that answers your question.  

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[Cadmanto]

Are you asking for the combination of both in the same model?  Top Down and Multi-body parts?

Personally, I use multi-body parts only when I have a purchased part that is an assembly.  Easier for me to just have one part file representing multiple parts then an assembly.

Top down I use once in a while for reverse engineering or when I have a lot of parts that are dependent on each other.

Hope that answers your question.  

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[aurel_e]

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@Cadmanto wrote:

Top down I use ..... when I have a lot of parts that are dependent on each other.

Hope that answers your question.  

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

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I use it a lot when I have parts that are dependent on each other. I find it easy to modify and reliable. a basic example 2 parts with slots and holes. If I change the position I change the dimension in the master without having to open both files.

The reason I asked is because I was involved in a discussion in the Italian forum, and it looks I am the only one that use it. The people  were advising a new Inventor user to absolutely avoid this technique as they don't see any benefit.

[aurel_e]

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@Cadmanto wrote:

Top down I use ..... when I have a lot of parts that are dependent on each other.

Hope that answers your question.  

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

---

I use it a lot when I have parts that are dependent on each other. I find it easy to modify and reliable. a basic example 2 parts with slots and holes. If I change the position I change the dimension in the master without having to open both files.

The reason I asked is because I was involved in a discussion in the Italian forum, and it looks I am the only one that use it. The people  were advising a new Inventor user to absolutely avoid this technique as they don't see any benefit.

[Cadmanto]

It all depends on the industry you are involved in.  One thing to keep in mind is with top down there is a lot of associativity.   That can pose issues when it comes to using these parts in other assemblies when the connections are still there.  May or may not cause problems in the grand scheme with multi levels of assemblies.

I hope this makes sense.

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[Cadmanto]

It all depends on the industry you are involved in.  One thing to keep in mind is with top down there is a lot of associativity.   That can pose issues when it comes to using these parts in other assemblies when the connections are still there.  May or may not cause problems in the grand scheme with multi levels of assemblies.

I hope this makes sense.

Windows 10 x64 -16GB Ram
Intel i7-6700 @ 3.41ghz
nVidia GTS 250 - 1 GB
Inventor Pro 2018

[Frederick_Law]

I avoid multi-body and use Master Skeleton.

One part, one file, one drawing.

Multi-body is good until you need to make drawings.

Try work on someone else multi-body part.  Good luck finding the feature you need to make any changes.

[Frederick_Law]

I avoid multi-body and use Master Skeleton.

One part, one file, one drawing.

Multi-body is good until you need to make drawings.

Try work on someone else multi-body part.  Good luck finding the feature you need to make any changes.

[Anonymous]

I love the multi-body part modeling because I don't have to save each part in its own file name then insert in the assembly and constraint it to another part.

I do a lot of system layout in the existing factory floor layout. I got .dwg or PDF plan view and I just created a simple .ipt file bring the .PDF or .dwg and from there I created and as I extrude I check multibody box. I cacreateed the whole floor layout and derive my own subassembly in for ref. I can build the assembly from a single part.

When the project kick-off approved by the customer then I just make parts from that multi-body part to created assembly and still control those parts from the multi-body parts.

I also use that multi-body as a skeleton for Frame Generator.

P.s

Multi-body modeling is very good for idea and concept too.

Now Inventor sheet metal can be done on multi-body part too but you can not make a flat pattern.

If I need flat pattern then I export that body out to part set metal thickness then make a flat pattern.

[Anonymous]

I love the multi-body part modeling because I don't have to save each part in its own file name then insert in the assembly and constraint it to another part.

I do a lot of system layout in the existing factory floor layout. I got .dwg or PDF plan view and I just created a simple .ipt file bring the .PDF or .dwg and from there I created and as I extrude I check multibody box. I cacreateed the whole floor layout and derive my own subassembly in for ref. I can build the assembly from a single part.

When the project kick-off approved by the customer then I just make parts from that multi-body part to created assembly and still control those parts from the multi-body parts.

I also use that multi-body as a skeleton for Frame Generator.

P.s

Multi-body modeling is very good for idea and concept too.

Now Inventor sheet metal can be done on multi-body part too but you can not make a flat pattern.

If I need flat pattern then I export that body out to part set metal thickness then make a flat pattern.

[SBix26]

I use multi-body top-down design most of the time.  There are very few reasons to avoid it, and many reasons to embrace it.  It saves me considerable time in design, is robust, nearly bullet-proof.  In more complex designs it can be used with skeletal modeling (another form of top-down design).

My last complex design project before retiring had two Frame Generator assemblies and several other fairly complicated subassemblies, all done with multi-body solids and ultimately laid out from a single sketch.  When I needed a bit more room, I modified one dimension in the master plan sketch, hit update in the top level assembly, and everything adjusted to the revised dimension-- frames and all the other subassemblies, and all their components, etc.

It requires some planning and forethought, but it's powerful.  Major downside: feature patterns aren't recognized at the assembly level for patterning components.

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Sam B
Inventor Pro 2019.3 | Windows 7 SP1
LinkedIn

[SBix26]

I use multi-body top-down design most of the time.  There are very few reasons to avoid it, and many reasons to embrace it.  It saves me considerable time in design, is robust, nearly bullet-proof.  In more complex designs it can be used with skeletal modeling (another form of top-down design).

My last complex design project before retiring had two Frame Generator assemblies and several other fairly complicated subassemblies, all done with multi-body solids and ultimately laid out from a single sketch.  When I needed a bit more room, I modified one dimension in the master plan sketch, hit update in the top level assembly, and everything adjusted to the revised dimension-- frames and all the other subassemblies, and all their components, etc.

It requires some planning and forethought, but it's powerful.  Major downside: feature patterns aren't recognized at the assembly level for patterning components.

---

Sam B
Inventor Pro 2019.3 | Windows 7 SP1
LinkedIn

[jtylerbc]

At my company we do mostly welded steel fabrication.  The arguments against it (including in this thread) mostly revolve around reusing parts in other assemblies.  This is an infrequent thing to do in our situation anyway, so there is no reason for us to avoid the technique.  Most of us have taken to using multibody techniques for our plate and sheet metal weldments.  Sometimes this same multibody part also serves as the layout for a Frame Generator model, tying the plate portions of the model to structural steel framing.

On more complex projects, we will sometimes have more than one multibody model connected to each other via linked parameters.

We also sometimes use the multibody (or a part derived from it) for finite element analysis.  It had long been our practice to derive assemblies into a multibody part to make model simplification for analysis easier.  At some point we realized that it was even cleaner if we just made the FEA model (either directly or Derived) from the multibody part.  We often have the bulk of the analysis done before we ever generate any of the individual parts.

[jtylerbc]

At my company we do mostly welded steel fabrication.  The arguments against it (including in this thread) mostly revolve around reusing parts in other assemblies.  This is an infrequent thing to do in our situation anyway, so there is no reason for us to avoid the technique.  Most of us have taken to using multibody techniques for our plate and sheet metal weldments.  Sometimes this same multibody part also serves as the layout for a Frame Generator model, tying the plate portions of the model to structural steel framing.

On more complex projects, we will sometimes have more than one multibody model connected to each other via linked parameters.

We also sometimes use the multibody (or a part derived from it) for finite element analysis.  It had long been our practice to derive assemblies into a multibody part to make model simplification for analysis easier.  At some point we realized that it was even cleaner if we just made the FEA model (either directly or Derived) from the multibody part.  We often have the bulk of the analysis done before we ever generate any of the individual parts.

[johnsonshiue]

Hi Guys,

I personally think the term "Top-Down Design" is a bit confusing. It was coined as an opposite to "Bottom-Up Design." In reality, nobody does pure "Top-Down" or "Bottom-Up" (except Lego builders). You rarely start from scratch. You always work on something already there, adding, editing, tweaking stuff.

Multi-solid body workflows are powerful. It is best when there is a lot of inter-component geometric dependency. But, you probably would not use it to design a half-million components assembly. These workflows are there for a reason. As a designer or an engineer, you have to choose your path properly. There is no wrong workflow, as long as it is repeatable and usable.

Many thanks!

[johnsonshiue]

Hi Guys,

I personally think the term "Top-Down Design" is a bit confusing. It was coined as an opposite to "Bottom-Up Design." In reality, nobody does pure "Top-Down" or "Bottom-Up" (except Lego builders). You rarely start from scratch. You always work on something already there, adding, editing, tweaking stuff.

Multi-solid body workflows are powerful. It is best when there is a lot of inter-component geometric dependency. But, you probably would not use it to design a half-million components assembly. These workflows are there for a reason. As a designer or an engineer, you have to choose your path properly. There is no wrong workflow, as long as it is repeatable and usable.

Many thanks!