Method to accurately position the components of a subassembly in an assembly 3

[DobsS]

Hi guys,
Note: I tried searching for a useful string, but couldn’t find much and didn’t know how best to word the search.
Please advise the best method (I am using Solidworks 2012 and 2013).
The one I use currently is:
• edit the sub-assembly in the context of the assembly and use 3D sketches to take reference surfaces, reference axis etc.
• Open the sub-assembly and use the references to position and mate the components.
It seems laborious and clogs up the sub-assembly with the 3D sketches.
I wonder if there is a better method.
Would it be possible to use flexible sub-assemblies, locate the components by mating them in the assembly (which is easy and straightforward), but then somehow “freeze” or transfer the new sub-assembly positional situation in the actual sub-assembly file?

Thank you.

 

[PatCouture]

It really depends on your needs and your workflow! I'm having a hard time understanding why you would want the part in a subassembly while their position would be defined in the parent assembly. If you don't need the associativity, you can insert all the parts and position them in the parent assembly and then transfer them to the sub-assembly and fix all their position but there's a lot of downside to this so I'm sure you don't want that. Another way is like you described with the "in-context reference" and the reference planes and/or 3D sketches. The third method I could suggest is to create what I call a "Skeleton part" This would be a part used exclusively to contain all the reference planes and sketches and since it's a separate part you can either use it in the sub-assembly for mating or inside each part so that the origin is always the same for the sub-assembly.

I still much prefer having sub-assemblies where parts don't have to move in the parent assembly but I know sometimes it may not be possible.

Cheers

Patrick

 

[EEnd]

It sounds like you might be attempting top-down design. If so, Patrick's suggestion of "skeleton part" in addition to "layout sketch" and "top-down design" might be good search terms.

If not, providing a little more detail about why you want to position components relative to elements in higher level assemblies will allow us to provide better suggestions about how to go about it.

Eric

 

[TheTick]

Interesting. I often do similar things, using 3D sketches to provide temporary or permanent context. Using sketches has an inherent robustitude that other methods do not.

If you feel you have no further need for the 3D sketches, then delete them and the related mates. Use a "Lock" mate or fix the component to finalize its position.

Some ultra-orthodox top-downers insist on live context for everything. This is usually more trouble than it is worth. With your method, you can always "reconnect" under the same or even brand new contexts and reposition as needed. The time to adjust is usually less than the time it takes to set up and maintain live context that is usually more trouble than it is worth.

 

[DobsS]

Guys,
Thanks for the answers, they all help in a different way.
Let me define the need that Pat was asking for (and I agree that normally you wouldn't want the hassle of defining in the top level the position of a component in a sub-assembly).
Case 1: team work, with each member of the team working on a different subassembly and one member controlling the top level. I have to locate all the components in my system referenced to the top level and mind you, they are not all connected to each other. One sensor, or connector, or clamp, or filter can be floating in space in my group of parts, but will have to land in a specific spot in the top level assembly.
Case 2: kits. We do create service kits of parts customers may order and we want them located exactly as they would be positioned on the top level (some believe this is helping the customers).

The main thing though that explains why I need this way to locate components is this: in my subassemblies not all items are connected. I don't have a problem with those that are. Some though are "floating" in the subassembly, and only become "grounded" when you look at the top level: there are a few sensors a few connectors, a few P-clamps and stuff like that, which need to be part of my system (functional reasons) but only get located by components that are not "mine" they are part of somebody else’s work (top level).

The skeleton idea can work, I'll give it a try, thanks.
TheTick: I am not fanatical about the in-context links, a lot of times I like to break them after using them; not always, but many times, so I see your point.
Thanks guys.

 

[ctopher]

You can add all your parts in an assy, mate them, then create the subassy's. Insert/Component/Assembly from selected components.

Chris, CSWA
SolidWorks '15
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[DobsS]

To ctopher: "You can add all your parts in an assy, mate them, then create the subassy's. Insert/Component/Assembly from selected components."

I have to admit I don't really understand the idea. If I go Insert / Component / Assembly in the top level, unless I am missing something, I think I will end up in the situation I am in now: editing a subassembly in the context of the top level.
Can you please detail a bit?

 

[ctopher]

I think you will need to mate all components in the subassy's, then mate the subassy to the next assy.
If you use the top down design approach, create all of the parts this way, then you can create subassy's by selecting the components as I mentioned above.
Does this help? Link

Chris, CSWA
SolidWorks '15
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[DobsS]

ctopher, this looks interesting, I need to try it. I didn't know about the possibility to add to a sub-assembly as you describe. Thanks, will try on a mock top level.

 

[DobsS]

Ctopher, here is what I found (or understood, as this is what you may have been trying to explain to me) - which probably most of you already knew: In order to obtain a sub-assembly with the components perfectly positioned in the top level assembly, even though they may be "floating" and not connected to anything in the sub-assembly, you can do this:
Say you start with a core sub-assembly of components all connected to each other and the whole sub-assembly inserted and mated into the top level.
Now, you want to add component(s), that for some reason (functional, commercial, service kit etc.) need to belong to the sub-assembly, but they also need to be located perfectly matching something in the top level; also the new component doesn't connect to anything in the sub-assembly (just "floating" in there).
[ol 1]
[li]Insert the new component in the top level.[/li]
[li]Mate it completely to what it needs to mate to.[/li]
[li]Use Tools / Reorganize Components and move it to the sub-assembly.[/li]
[li]The mates in the top-level will break. Delete them.[/li]
[li]Open the sub-assembly. The newly added component will show there free of any mates.[/li]
[li]Fix it, or mate it in the sub-assy so that it maintains the current position.[/li]
[/ol]

This method allowed me to perfectly locate all components without using any reference elements, 3D sketches, planes or axes.
Of course, this can work both as an advantage or a disadvantage.
At this point I am going to say it will be a judgement call if next time I will use the skeleton method (thanks PatCouture) or the Re-organize Components method (thanks ctopher).

Thanks to all guys, this was a good learning post for me.
DobsS

 

[ctopher]

Good.
Thanks!

Chris, CSWA
SolidWorks '15
ctophers home
SolidWorks Legion