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In-context modeling feedback loop – am I doing it wrong?
I've been trying to wrap my mind around the part studio → assembly pipeline, and how I can build a workflow out of those.
I mostly design parts for 3d printing (FDM, MJF). Usually, 3d printed parts are coupled with non-3d-printed parts, e.g. nuts, bolts, washers, electronics, etc. Therefore, the 3d printed design is often derived from how those already existing parts are shaped. So far I can see two approaches to modeling this:
(A)
- Design all existing parts in separate part studios
- Create an assembly
- Align the non-3d-printed parts approximately in the assembly
- Create part studio in context
- Create another assembly that combines all parts
This approach has problems that I wasn't able to find solutions for:
- The first assembly will have mates that don't really represent real mates on the final assembly, e.g. random bolts and nuts floating in the air not tied to anything
- The shape of 3d printed parts will be set by first assembly, but it's not possible to adjust mates while looking at the resulting parts, you have to first update dimensions, then update the context, so it's not very visual
- Every time I need to add or remove non-3d-printed part, I have to do so in two assemblies
(B)
- Design all parts in one part studio
- Create an assembly and import all parts there
On the surface, this is already a better workflow, but:
- The document gets slow when everything is designed and regenerated in one place
- I can't use the same non-existing-part twice: it will be considered a separate part
- Overall it feels that I'm doing something wrong and this is not how OnShape is intended to be used
However, this does give you the benefit of real-time feedback on design changes (you can even use a variable to adjust dimensions of the whole design), in a way, it feels much more parametric and "procedural" than the workflow (A).
So my question is: which workflow do you prefer for 3d printing? How is it intended to be used? I'm just about to start a new design and I wanted to figure it out before I design myself into a corner again.
Comments
I' trying to under stand your work flow, What is the second assembly supposed to accomplish? Is it your assembly that is slowing down or the part studio or both?
Typical work flow for me would be to start with part studio to begin fabricated parts.
Build assembly and edit first part studio in context for things like bolt holes. Start with insertion of rigid parts like motors and cylinders(they may be subassemblies, Not exactly rigid but fixed within constraints). Subassemblies provide better focus with out the clutter of main assy.
If you want a new part studio because first one is getting slow then start a new context that new parts will go into or because you'd like separate types of fabricated parts. Sheet metal, weldments, frames, 3 printed, etc.
If the assembly is slowing down you can move groups of parts into subassemblies. Your exiting mates will be brought with and should continue to work.
Building a second reference assembly sounds like a of work and some confusion to my mind. Which one am I working on and why are my mates not behaving as expected?
This is the part that I don't like very much because I don't yet know where I will need bolt holes but I have to lay out all non-3d-printed components so that I can start modeling.
I guess ideally there would be some sort of hybrid between Assembly and Part Studio view where one can insert a bunch of parts and then start modeling and be able to reference those parts, without needing to switch views and update context for every small update.
There I can finally define mates between all the parts. I also tried inserting newly modeled parts into the 1st assembly, but understandably it creates quite a mess.
Generally creating multiple parts in a single part studio is the more efficient option. However it doesn't necessarily have to be everything in one part studio. It can make sense to split things up a bit and use some of the "top down" techniques like derive features with layout sketches/reference geometry. I would recommend checking out the top down courses if you haven't already: https://learn.onshape.com/catalog?labels=%5B%22Learning%20Format%22%2C%22Topic%22%5D&query=top%20down&values=%5B%22Course%22%2C%22Top-Down%20Modeling%22%5D
Regardless you want to generate an assembly where you add all the fasteners and check the fit and not "pattern" parts in a part studio.
Instead of throwing thing randomly in an assembly and using contexts, say you have a circuit board, you can import that, create a sketch with the mounting holes and add some reference locations in that sketch (or others) for mounting bolts etc. You can then derive that sketch into you part studio(s), as well as insert it into an assembly. This way you can control the location of the bolts in the assembly by editing the sketch and it will update "live" in both the assembly and your part studio. You can open the assembly and part studio in different browser windows to see all of it at once.
Another way to put it. Don't start with the assembly, start with "reference geometry" (could be sketche(s) or even some simple solid shapes) that has the overall/key dimensions of all your the parts in your assembly and use that to drive things in both assembly and parts studio(s). See:
https://learn.onshape.com/learn/course/master-model/introduction-to-master-model-workflows/defining-master-model-techniques
Okay thanks a lot @eric_pesty ! This does sound better and I think what I've been missing is the "derive" feature in my workflow. I'll give it a try 👍
Yes, "Derive" is a very useful tool for many workflows. Hopefully that works for you.
Might worth watching through some Greg Brown's videos, for example this latest one:
This one is going pretty far in-depth but could give you some ideas.
@eric_pesty I wrote a publish geometry FS this morning after seeing the video.
https://cad.onshape.com/documents/7f55a766ea863bf697365ac7/w/2ebaef8d6219e7e2b497bdeb/e/7188f69065381288a8f983f9