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Struggling with the "correct" modeling order
jeremiah_peschka840
Member Posts: 23 PRO
I'm attempting to do a top-down approach to modeling and, as the title says, I'm struggling with the right order to model a chair.
I started by modeling the back leg of the chair and as a separate part studio and then placing that into an assembly. I then modeled the front leg in a separate part studio and that's where I got stuck.
My goal was to create the front and back legs as separate part studios and then set them a fixed distance apart in an assembly. This seems like the wrong approach since there's no clear way to "mate" with a distance between two points. (Width almost seemed like it, but it isn't quite what I wanted.)
My next thought on how to do this correctly is to make a sketch of the chair in one part studio, mate that to the origin in the assembly, and then create the parts. This still seems brittle, though.
What would be the preferred approach to modeling this in OnShape?
Comments
Without knowing what the chair looks like or the manufacturing processes etc, it's hard to give a definitive answer, but typically a single part studio would be the way to go. I would only do separate part studios if the individual parts had hundreds of features. In which case, I would still most likely have some sort of top level part studio which lays out the basic dimensions and geometry.
If you model in a single part studio, you can insert the parts as rigid into an assembly. That will mean no need for mates (other than something to the origin, or a fix). The assembly is also (now) where you would make mirror parts (assuming there are left/right flavors of legs).
Simon Gatrall | Product Development, Engineering, Design, Onshape | Ex- IDEO, PCH, Unagi, Carbon | LinkedIn
Exactly what S1mon said.
I am a new user of OS, but have done 100s of top down designs…the way OS is setup is logical but just different enough to other CAD that it takes some adjustment.
The "Part Studio" is a bit of a misnomer. It implies a singular part (to me anyway), but is really just the basic modeling space. Top down design in OS can be done within a single Part Studio, or across multiple studios using one studio as the top or skeleton. Whatever works for you.
Thank you both. This makes a lot of sense.
As for the type of chair: it's a basic dining chair - four legs, back, seat, and some stretchers. Once I saw S1mon's response, I realized that I could've been more descriptive - a recliner could require much more modeling than a dining chair.
I have used multiple part studios for more complex furniture where each component might require a good bit of CNC time. In that case, the top down design with many studios made sense to me. Plus everything was "anchored" off of a frame.
It seemed like it would be annoying to put a mate connector at the bottom of every mortise and on the end of every tenon. A single Part Studio makes the most sense. I'll try to remember to post a render of the chair when I get done.
Def for a typical kitchen/dining chair do the whole thing in one part studio.
If you were trying to learn top-down modeling just for the fun of it, there would typically be a master model of the chair's basic shape. It could be in block solid form, surfaces, or even simply curves, representing the seat, back, legs, arms, etc. Then there would be one part studio for the seat and its first feature would be the derived seat from the master model. All the seat details would then be modeled there. Repeat for the other parts.
Now, lets say you want the chair to be twice as tall, you'd adjust it in the maester model, and all the part studios with the derived first features will adjust automatically.
That's one way to do top-down modeling. A couple others. But the easiest and best for small assemblies is to do it in one part studio.