topic Re: sculpt problem in Fusion Design, Validate & Document Forum

sculpt problem

jwrockstarr0 — Fri, 16 Sep 2016 05:04:16 GMT

I purchased a 3D file of a hard hat (attached) and I want to lengthen the bill portion. I cannot figure out how to edit the mesh so I converted the hardhat to a t-spline but whenever I try press-pull, Fusion 360 crashes. It also crashes with the STEP file. At this point I would be happy just to fake it and create a larger bill to cover the existing one but I'm too inexperienced to figure it out.

I would like to know 1) if this file is editable and/or 2) how to create a 3D bill form.

Re: sculpt problem

Anonymous — Fri, 16 Sep 2016 06:47:36 GMT

I would guess that crashes are related to your specific PC configuration, because I can edit your TS without a problem:

Re: sculpt problem

jeff_strater — Fri, 16 Sep 2016 14:20:59 GMT

Hi @jwrockstarr0,

When Fusion crashed, did you see a Crash Report dialog? I did a search in our crash report system, and there seems to be no crashes from you since Sept 10.

As, @Anonymous indicates, you can edit the TSpline in this model fairly well. However, in your post you indicate that you used "Press/Pull". That may be part of the problem. Press/Pull does not work with TSpline bodies. Because you converted the mesh bodies into a TSpline, when you exited Sculpt mode, that was converted to a solid body:

When I tried using Press/Pull on this body, I did see Fusion freeze up for a very long time. I don't think it actually crashed, but I definitely saw it "thinking" for a very long time. This should be investigated definitely. But, to get the results I think you are looking for, please follow @Anonymous's suggestions, and edit the TSpline using the Sculpt workspace.

Jeff

Re: sculpt problem

jwrockstarr0 — Fri, 16 Sep 2016 16:53:37 GMT

Thanks Jeff,

When I go into the sculpt environment, the solid hardhat is grayed out and not selectable. When I turn on the mesh hardhat, I can only select the whole body using Edit Form, nothing else.

Re: sculpt problem

Anonymous — Fri, 16 Sep 2016 23:09:49 GMT

@jwrockstarr0

Hi,

Maybe seeing the steps in my screencast will be of some help.

Re: sculpt problem

jeff_strater — Fri, 16 Sep 2016 23:49:04 GMT

@Anonymous's screencast shows the correct way to edit this design. Thank you for posting that - I got busy this afternoon, and never got back to this, unfortunately.

The images you posted show a "head" model that is not in the version that you posted earlier. My guess here (just a guess) is that you edited the Sculpt feature for the "head" model, and that is why the "hardhat" model is grayed out. If you look in the timeline, you will probably see more than one "sculpt" feature. Make sure that you select the correct one for the "hardhat" body and edit that one. If you can share a more recent version of the model with us, we can show you on your current model.

Also, I would recommend that you turn off the visibility of the mesh bodies, until you need them. They tend to clutter up the display, and because they overlap with the TSpline bodies (and look similar), that can add to the confusion.

Jeff

Re: sculpt problem

jwrockstarr0 — Sat, 17 Sep 2016 16:32:17 GMT

Jeff, to answer your first question, I did not get the normal error report with the earlier crashes.

I guess part of my problem lies in confusion of the terminology: Solid, mesh, Brep and Tspline. I'm still not sure what brep is. It might help if that was listed in "properties". I thought that I would bring the mesh into sculpt, convert it, finish form, and then edit it as a solid. (rather than stay in sculpt to edit)

Anyway, I opened a fresh file with the hardhat only, brought in into sculpt, converted it to tspline and was able to edit it, using soft modification. When I Finished Form I got an error message "failed to convert" I did finally manage to "repair body" and get it back into Model. I'm not sure what I'm supposed to do with the yellow stars, but autorepair did work.

So I went back to my working file and noticed that the mesh body is triangulated, not quad, so editing does not work. Not sure how this happened. I have the triangle box unchecked in preferences. I guess I'll just do a fresh upload. But at least I get the basic process now. Thanks so much.

Re: sculpt problem

jeff_strater — Mon, 19 Sep 2016 18:59:42 GMT

Hi @jwrockstarr0,

Good question about the different body types. I agree that this is not crystal-clear in Fusion today. We have:

BRep bodies. "BRep" stands for "boundary representation". This is a precise mathematical model of a body. So, a Cylinder is represented as the mathematical definition of a cylinder (axis, radius, length). There are two types of BRep bodies in Fusion. Solid and Surface. Solid models tend to be edited in the "Model" workspace, and define a closed region of material. You can do things like Shell on a solid. Surface bodies are infinitely thin bodies. They can be open or closed, but have no solid material properties (you cannot shell them, for instance)
TSpline bodies are available only in the Sculpt workspace. These bodies are primarily used to define "organic" (curvy) shapes. You can convert a TSpline body into a BRep (surface or solid), and this happens automatically, in a parametric design, when you exit the Sculpt workspace
Mesh bodies are more imprecise descriptions, containing a number of simple facets, usually triangles or quads. Mesh bodies (today) cannot be converted to another type, unless it is a quad mesh, in which case you can convert to a TSpline body

Glad that you were able to get your hardhat converted to TSpline, and eventually converted back to a BRep body. I'm not sure why it would not convert. If you want to share it, I'd take a look.

I'm not sure what happened with your original model. The one I have, the hardhat model is definitely quads, so I'm not sure how it got turned into triangles. Again, if you want to share that design, I'd also take a look at it

Jeff

Re: sculpt problem

PhilProcarioJr — Mon, 19 Sep 2016 20:12:15 GMT

@jeff_strater

"Mesh bodies are more imprecise descriptions, containing a number of simple facets, usually triangles or quads. Mesh bodies (today) cannot be converted to another type, unless it is a quad mesh, in which case you can convert to a TSpline body"

Mesh bodies (triangulated or quad) can be converted into B-reps....

Re: sculpt problem

jeff_strater — Mon, 19 Sep 2016 22:34:18 GMT

@PhilProcarioJr. This is certainly true. But, IMO, it's a bad idea. The idea of taking each triangle in a mesh body, and turning that into a BRep face can lead to problems. Some performance problems can result if you try to convert too big of a mesh to BRep. I wish, sometimes, we had not put this in, but you are right - it is there.

Jeff

Re: sculpt problem

jwrockstarr0 — Tue, 20 Sep 2016 04:28:18 GMT

Jeff, thanks for the clear explanation. I was able to modify the original mesh but, as you say, meshes are rather imprecise. I found that the coarseness of the facets made it difficult to get a smooth transition, at least at my level.

For what it's worth, I attached a screen shot of the one helmet file that I thought looked more like triangles than quads. I don't need this file anymore, but I would like to know what it is.

Thanks

Jay

Re: sculpt problem

PhilProcarioJr — Tue, 20 Sep 2016 23:06:07 GMT

@jeff_strater

That is one of the most useful tools in Fusion....don't you dare remove it.

I would be a very unhappy camper.

I agree that one needs to use caution with it but it is an essential tool.

Re: sculpt problem

jeff_strater — Wed, 21 Sep 2016 00:50:49 GMT

OK, @PhilProcarioJr, thanks for chiming in. I can see that it is useful. I don't have the power to take it out anyway , so no need for concern. It's not going away. As you say, maybe it should come with a "use with caution" warning.

Jeff

Re: sculpt problem

jeff_strater — Wed, 21 Sep 2016 00:54:07 GMT

yes, @jwrockstarr0, you are right. Those are definitely triangles. Somewhere along the line, the mesh got "triangulated", which does, as you point out, make it not useful for conversion to TSplines. I'm not sure how it happened, but if it comes up again, let me know. In theory, this should only happen if you have the "triangulate on import" option on, but there may be a bug where this can happen in other places.

Jeff