topic Re: Properties, CG and Mass in Fusion Design, Validate & Document Forum

Properties, CG and Mass

Anonymous — Wed, 03 Aug 2016 04:06:24 GMT

I might be missing something but here is the rub:

Invoking the properties dialog to check the overall assembly mass etc, will include hidden bodies that do not contribute to the final model.

A number of bodies are a by product of combines/splits etc. Deleting those is not an option (referenced material). Removing creates headaches and errors on rebuild/compute (i've tried).

I think it would be a good idea to have the properties calculated for shown entities only. Again unless i'm missing something.

Re: Properties, CG and Mass

masa.minohara — Wed, 03 Aug 2016 09:41:09 GMT

Hi @Anonymous,

Thank you for posting this! As far as I know this is a known limitation of Fusion 360. I agree with you about the idea and calculating only displayed bodies in a component would be useful. You may consider submitting your idea to the Fusion IdeaStation forum, which is constantly monitored by developers and product managers, and is currently the most effective way to request a product enhancement:

Autodesk Fusion 360 IdeaStation

Other forum users will have the opportunity to Vote or add Kudos to the Idea. Votes on an idea will increase the likelihood that an idea will be implemented.

Re: Properties, CG and Mass

jeff_strater — Thu, 04 Aug 2016 00:52:20 GMT

Hi @Anonymous,

This is a good question. I understand the issue. However, I have a couple of follow-on questions for you.

Do you really want visibility to affect Mass Properties? I understand the workflow you are describing here, but if we really have visibility affecting mass props, then any time you turn off a component or body because it is obscuring something that you want to see, you will affect the mass props. I know for myself, I would not want this behavior. If I just happen to forget to turn some components back on, then the properties would be incorrect.
Most likely, what is needed is another state, maybe "disabled" or something (can't think of a good name off the top of my head), which tells Fusion not to include this body or component in mass props calculations, and maybe other downstream operations such as CAM, SIM, drawings, etc. That, IMO, seems like a better idea for the idea station
I'd like to understand better why "Remove" doesn't work for you. It seems like this operation should be OK. It removes the body or component from the browser, from mass props, etc, but still leaves it in the data model for resolving references to it in earlier features. Do you have an example of where this won't work?

Thanks,

Jeff

Re: Properties, CG and Mass

Anonymous — Thu, 04 Aug 2016 12:01:40 GMT

Hi @jeff_strater

Thanks for chiming in.

Being able to get an accurate mass estimate is important. The way this is controlled inside the software can be as diverse as there are users. The way I see this working is by means of a "toggle". In my first post I mentioned visibility (light bulbs) to get the idea across. As for the idea station idea, you can use a check mark box like you have in the Simulation environment already.
Yes.
For this one, I have to start by saying that I may not model as per best practices, I just need to get out of the software what I need. I have 2 models each involving wing sections that start with surface/patch lofts and then building on top of that with extruded surfaces. After a few thickens, combines and removes, I run into a lot of red warnings pertaining to the removed bodies in the timeline. To the extent that I had to remodel again from scratch, because, first I don't know whether that warning is going to come back and bite, and second because the surface/patch loft tool is sub-par (but that's another discussion i guess).

I can give you access (or you give yourself access )to the model in question but that has to be done privately.

Re: Properties, CG and Mass

jeff_strater — Fri, 05 Aug 2016 22:49:26 GMT

Thanks @Anonymous. Your suggestion of using the UI from Simulation is a good one. To be honest, I hadn't thought of that, but if I understand what this does (I don't spend much time in simulation), it is essentially the same thing as an enabled/disabled flag. I'll pass that suggestion along for the modeling environment.

Regarding removing bodies: One of the subtle things in Fusion that often trips up even experienced users (and us) is the difference between "Delete" and "Remove" for bodies and components. Delete, for a body, will remove the body from all existence (essentially deleting the feature that created the body in the first place). This will definitely cause downstream failures - any reference to that body will fail, because it is no longer there. However, if you use the "Remove" command (which internally we call "soft delete"), then you are creating a new feature in the timeline that removes the body at that point in time. This allows references to the body to still succeed, as long as they come before that body in the timeline.

Here is a simple screencast showing this principle. In this screencast, I start with one body, then split that body with a workplane. Then, I move the new body out a ways, and construct a work axis through one of the edges. Then, I select that body and do "Remove". The body is gone from the design (and, for your requirements, will not affect mass props). But the work axis that depends on that new body still succeeds, and if you roll back before the Remove feature, the body re-appears.

It seems like this could work well for you.

Jeff