Re: Balloons and multi-body parts

Multi body might be very helpful while designing a part, but I still believe it is a methodological mistake to allow them in assemblies. This will cause much trouble in PDMs and other tools that make use of the design structure. Apparently it creates problems even in SW... What do you expect ? 2 balloons for a single entry in BOM ? 1 balloon and some bodies without any ? a single balloon attached to multiple bodies ? looks like SW decided to answer with a question mark ;-) Reminds me of the configurations, another great concept that can be misused as it lacks a clear usage framework (can be used for different sizes, different level of detail, optional features ... or even to defined completely different models in the same document...) Could somebody explain me when it is useful to consider multiple bodies as a single part in an assembly ?

Philippe Guglielmetti -

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Philippe Guglielmetti
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Eeek - you got me wrong. I had no intention of getting a balloon for each 'body' - just for the part as a whole.

I'm glad you said what you said - You are absolutley correct in lecturing that it is a 'methodolgogical mistake' to use them as a workaround for assemblies for real production work - it could get ugly. It is our company policy not to use multi-bodies to simulate several parts on production pieces, and I certainly hope that no one gets the impression otherwise.

That said, I was using multi-bodies a part in my assembly because I was trying to bang out a real, real quick drawing for quote purposes - sort of a clean 'sketch on a napkin'. This is a kiosk/cabinet, and I wanted to show a cleat on the inside face of one of the side panels but didn't want to trouble with all the mates and file management at this early stage in the design just to get a simple line that breaks the cleat away from the panel its mounted to (heck, I'd have a file for the cleat, then have to make another file to get the cleat and side panel together as a subassembly, then maybe need a mirrored subassembly for the other side, and some in-context references to be sure they update together - uggh). If the cleat was a merged, extruded boss instead of a multi-body, the part could be interpreted as a stupidly complex milled piece instead of just attaching two pieces of wood together. In this case - quick, throwaway drawing in the conceptual stage to generate a ballpark quote, on a part that never needs to be exploded, where I was working at 1:00 AM, I could not resist the temptation.

I just thought it was interesting that the balloon doesn't recognise the part.


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Edward T Eaton

Maybe this is SolidWorks' way of correcting the 'methodolgogical mistake' for a user and making sure that they don't try and use multi-body parts for an assy or bring a multi-body part into an assy. Not saying it is right for all but it could be a backhanded QA control for "non-expert" users.

Ken M.

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"Philippe Guglielmetti" wrote

Go Phil.

I agree with your caution on the use of multi body models in certain situations. It sounds like Ed was asking a different question, but here are my thoughts on the question you asked:

Multiple bodies in a part in an assembly are useful when...

- you don't need baloons on the bodies (thanks Ed)

- you don't want the bodies listed as parts in the BOM (although the "don't expand in BOM" is a better way to do this)

- you don't want dynamic motion between parts

- you don't want to detail the parts separately

- when the parts are purchased as an "inseparable subassembly"

I've been known to make multibody parts and used as "phantoms", where the part is never used anywhere, except to combine with the "split" function to make the bodies into separate parts and then an assembly. I do this to avoid combining incontext with configurations. For example, to make several size configurations of incontext hinges, where you need dynamic motion, but you also want configurations and relationships between parts. Things that you otherwise might not combine.


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I've found multibody parts useful for mocking up cabling assemblies / harnesses -ie get rough idea of dims required from part, and model cabling assem seperately, without turning main assembly performance to concrete and generating extra work creating installed and unfurled (flat) configurations for the fab dwgs.

Can then use these dummy parts in the main BOM.

Not ideal (hint, Solidworks: can we have a replacement for Embassyworks, please?) but gets me out of a hole when time is short.

Can't always balloon them, though...


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Interesting... I'm on SP3.1 as well, but I get a brown balloon with a question mark in it.

Another thing - attempting to create a reference dim off of the edge of a multi-body part seems to be spotty. Most of the time, SW simply doesn't recognize that there is an edge - I might as well be clicking on blank screen space. I have to show the underlying sketches and click them (or better yet - just insert the dims from the part per our company policy) in order to get a couple of quick overall dimensions for quote.

Yet sometimes, SW does recognize the model edge. Odd.....

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