How to simplify the assembly?

miczech

Hello all,

so, pretty soon after starting using Onshape I have encountered this problem:
I uploaded a model I want to use in another assembly but then, whole document is just too big for Onshape to work fluently. I am not focused on that heavy design I have just uploaded, I am just interested in shape/volume/boarder dimensions. Usually I would have two possibilities:
1st: create very schematic, simply shaped, 3D, 1 part draft of the piece I am interested in,
2nd and quite often used when the more detailed shape is needed: create multi-body, one part document. it is light and it has the exact shape of original assembly.

I understand in Onshape it can be performed with boolean feature?
And here comes my problem:
Apparently Onshape will only allow me to make the "union" if there is a contact between parts. In other words, my assembly includes 277 parts but "union" will work, in my case, only for 222 of them as the rest is "floating" (there is e.g. 0.5mm distance between parts).

What should I do?
Am I using correct feature? Or are there any other which will allow me to "thin-up"  and simplify the assembly?

Thank you in advance for your help. I hope I described my problem clearly enough for you to understand.

mlaflecheCAD

If there is no contact between surfaces, I could create an assembly of all the parts and use the "Group" option to make sure they move as one in the upper level assembly.

There is also a feature you can use called Fix PCB, intended to do almost the same thing you are looking for  https://cad.onshape.com/documents/9a9b81d17d4b69e58ad9b0b0/v/c253688ad8add5efd222a709/e/3152191074466a8b45231663#_ga=2.170399136.1436770626.1565010688-1407455194.1565010688

Michael_Coffee

@mlaflecheCAD

I had the same situation as @adam_józef above and did much the same as what you're suggesting, creating a "Group" of them in a separate assembly tab and using it as if it were a single part. However, the feature script you've listed looks like a very powerful tool for imported models that need to be considered a single part for the purposes of what we need. My question is how does Fix PCB handle when an import comes in as surfaces and not as individual parts?

miczech

@mlaflecheCAD well apparently the feature you've recommended (Fix PCB) works PERFECTLY. Thank you very much.
Although, I am a bit surprised it is not basic feature in Onshape as from my perspective this type of operation is not something very uncommon.

Thank you again!

mlaflecheCAD

@Michael_Coffee the best thing in the surfaces use case is to do also group them in the assembly,  as you can add parts, sketches, as well as surfaces to an assembly.  Just make sure to turn on the filter when using the Insert tool to make sure surfaces are imported.

miczech

I need to refresh the topic as the problem for the surfaces (as @Michael_Coffee mentioned) is still present.
example: I have a PCB with 200+ parts, where making simplified model is not a problem using Fix PCB. At the same time, there is 3000+ surfaces in the same PCB and clearly, Fix PCB won't work on it (as any other operations). Grouping and packing into sub assemblies solves the problem only superficially as it looks nice on the ladder but Onshape still has to operate the document with 3k+ elements.
In that case I have just took a volume of the pieces and created simplified block myself as it is the fastest "solution" I came up with.
@mlaflecheCAD would you have any suggestions? I know that the problem is on the design side as surfaces in general cause problems and in that case i should have received assembly with solid parts.

regards,

owen_sparks

Just curious, are you importing from Altium?
Owen S.

mlaflecheCAD

@adam_józef I would eliminate any extra surfaces that are not required using the "Delete Part" command in the Part Studio containing the surfaces.

Michael_Coffee

@owen_sparks

We brought in a SolidWorks part into Onshape that was a surface model, rather than made from any features or sketches. If I remember correctly, a "Save As" was made of the originally assembly and saved as a part file, containing only surface information. Why it was done like this originally, I have no clue.

owen_sparks

Ah-ha, thanks for the background.  As you've probably guessed I've had some "fun" using PCB's from Altium. 

I'm used to suspect vendor CAD being blown into surfaces but in this case it was our own designs.  Altium helpfully seemed to export solids and surfaces for each component.  Helpfully some of the solids were also duplicated with both high and low detail versions of each component!  (We checked on Creo and it showed the same result so no finger pointing at Onshape was warranted.) 

The fix PCB FS was most helpful!

Cheers, Owen S.