Q's after watching Assembly video re body/components and joints

[Noah_Katz]

Watched this excellent video http://au.autodesk.com/au-online/classes-on-demand/class-catalog/2016/fusion-360/pd19577#chapter=0

and have a couple of questions:

1) Re bodies vs. components, it said 

- If you know the model will be a part start by creating a component

- If you are exploring a design use bodies

Some elaboration on that would be helpful, as quite often I know it will be a part but want to explore its design possibilities

2) A bit before the 50:00 minute mark, using a crankshaft assembly w/piston/connecting rod subassemblies, it was shown how adding a revolute constraint between one of the piston's wrist pin holes and the matching hole in the connecting rod added the constraint to the other piston/connecting rod subassembly.

One thing I noticed is that the top level asy was activated; is it correct to conclude that joints don't belong to any particular (sub)assembly, just to the component(s) they share?

Also, I was hoping to see what happened when a joint between the big end of the rod and the crank journal was created.

Presumably since the joint would contain a component outside of the piston/rod subassembly, it wouldn't try to duplicate it on the other instance - right?

[jeevesme]

1. I've found that almost 90% of the time, I use components.  This is because components let you do more with your model than bodies.  Also, if you start out with bodies to just explore designs, and you find a design you want, once you convert it to a body, the history portion of it does not follow it.  It stays in the topmost component. So if you want to change something after you convert it, you have to go to the topmost component to do it.  FYI, you are always working with at least one component, ie, the topmost component.

2. You will only have one Joints folder, it is located toward the top.  It does not matter what components have joints, they will always show up in that one top Joints folder.

"Presumably since the joint would contain a component outside of the piston/rod subassembly, it wouldn't try to duplicate it on the other instance - right?"

I'm not sure what instance you are talking about.  There is only one instance of the crankshaft in the model.

[HughesTooling]

---

@jeevesme wrote:

2. You will only have one Joints folder, it is located toward the top.  It does not matter what components have joints, they will always show up in that one top Joints folder.

This isn't quite right. The joint will be added to a folder that contains both components. So if you have a subassembly with 2 components and add a joint the joints folder will be in the subassembly component that contains the components. If you make a joint between components in different subassemblies the joint will be created in the component above the subassemblies, this might be the main component but it depends on how many nested subassemblies you have.

Mark

[HughesTooling]

Here's an example of joint folders in subassemblies within subassemblies.

before.png

[jeevesme]

I agree, that was only part of the story. Any joints made from components will always be at the top, any joints from subcomponents will be in the parent components folder.

[jeevesme]

On that note @HughesTooling,

https://forums.autodesk.com/t5/design-validate-document/are-components-subcomponents-the-same-as-ass...

[Noah_Katz]

Brian,

Let me put it this way:

"If you are exploring a design use bodies" implies that there there is something about components that limits exploration; what might that be?

>  There is only one instance of the crankshaft in the model.

I was referring to the two instances of the piston/rod subasy.

Mark,

Thanks, that helps clarify things.

[jeevesme]

Here are some good discussions on bodies and components:

https://forums.autodesk.com/t5/post-your-tips-and-tutorials/fusion-360-r-u-l-e-1-and-2/td-p/6581749

https://forums.autodesk.com/t5/design-validate-document/why-do-we-need-bodies/m-p/6680847#M81230

[Noah_Katz]

I read all of the links, and don't see an answer to

"If you are exploring a design use bodies" implies that there there is something about components that limits exploration; what might that be?

[HughesTooling]

It might be quicker to design with bodies and not worry about managing components, the down side is a project can become hard to edit with all your bodies and sketches in the main component.

An analogy for you, think of it's like a journey. If all you're interested in is getting from A to B as quickly as possible use bodies. But when you get to B if it's not what you want you might have to start from scratch.

But if you use components and plan ahead it will give you more options to change your mind and reuse and edit parts. So if you find B is not where you wanted to end up you can easily find your way to C, D etc. without going all the way back and starting from A.

Mark

[TrippyLighting · Accepted solution]

You can try to understand these concepts purely theoretically, however, to really understand the advantages of either, you really need to dive in and design things with increasing complexity.

Here is a  guideline:

If you are designing an object with complex geometry and surfaces it is often necessary to use the different modeling methods available in Fusion 360 and combine the bodies generated by these to achieve the final form of the object. In that case it might be better to start the design with bodies only, because it takes a number of bodies to get to the end result.

If you design a machine, e.g. a 3D printer it is wise to start with components following Fusion 360's R.U.L.E #1. You will have many components with only a single body in it that will need to be joined and organized in assemblies and subassemblies.

[Noah_Katz]

> ...In that case it might be better to start the design with bodies only, because it takes a number of bodies to get to the end result.

Ah, that makes sense - thanks!

[Noah_Katz]

been catching up on kudos I was remiss in giving for the time people have taken to answer my many questions, and on re-reading this

>  In that case it might be better to start the design with bodies only, because it takes a number of bodies to get to the end result

the question arises- are there bodies that cannot be created within a component?