Can Fusion be used for surfacing reliably?

[nkloski]

I keep banging my head on whether Fusion can create 3D models that are:  1) partially spline based and 2) constant wall thickness.

I am talking about something like this:

If you want to see the originating 3D scan of this, here it is (I cannot share the file publicly):    https://a360.co/3fPMfzY 

....Can Fusion's surfacing tools reliably create this?  Can I 3D sketch the edges and expect the Thicken tool to properly work?  Are there other tools in the autodesk portfolio which are designed to properly create shapes like these?

Or are all components like this really just tweaked until they come out right in a brute force try-try-try until the parametrics work out sort of way....or is there an easier way?

Thanks!

[JamieGilchrist]

Hi @nkloski ,

can you share the model?  I can't download from the link you provided.  If you can't share it publicly you can email me directly [email protected]

[nkloski]

I will send it privately, thank you.

[TrippyLighting · Accepted solution]

The surface modeling of this is fairly straight forward and simple. 

The part that takes experience is to "read" the geometry and understand how components like this are modeled in their original designs. That will help in reverse engineering the geometry.

Reverse engineering this properly will take patience and the right techniques .. which aren't all that difficult 😉

The outer surface that defines the curved shape of the light is easy to do but would unlikely involve any 3D sketch at all!

2D sketches and simple control point splines. I would overbuild the base surface and and trim away the excess. Creating that surface takes a little bit of tweaking but I would not call that "brute force" Surfacing takes time and deliberation. There is simply a lot of geometry in this part and that is going to take a lot of work, depending on how detailed you want to be in your model.

The title of the topic indicates that this is a complex surfacing problem, which might be hard to accomplish in Fusion 360. That isn't the case at all.

[chrisplyler]

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@nkloski wrote:

Or are all components like this really just tweaked until they come out right in a brute force try-try-try until the parametrics work out sort of way....or is there an easier way?

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I am not exactly sure what you mean. Sure, all components are like that if you don't know what you're doing.

Getting parametric things to "work out" requires pre-planning what relationships you want, the way you may wish to tweak those relationships later, and setting up the model to accommodate those requirements.

A part such as the one you posted isn't difficult...it, just like every other complex piece of geometry, is really just a lot of simple shapes all put together. But because of that fact, it will be time consuming, and there will be a lot of chances to set up the parametric stuff in ways that aren't desirable.

That type of part would typically be modeled by a professional, full time, automotive lighting engineer type person.

If you're experienced, thoughtful, and actually know what you want to achieve, it is certainly doable...but you aren't going to install Fusion for the first time and have it done well over night.

[nkloski]

I appreciate the replies so far, thank you!  For someone who is not a mechanical engineer by education, is there a place where learning resources concerning the segmentation process for how you would approach models like this can be accessed?

Also, in my experience, surfacing tools in Fusion do not properly thicken with delightfully aligned edges.  Maybe this is because I was trying to thicken 3D splines.  Just like there is a "Loft With Guide Surface"....is there a way to "Thicken with Guide Surface" to finely tune/control the resulting edges from a Thicken command to "point" in specific directions?

[chrisplyler]

A Thicken event will always try to move corners/edges normal to the surface.

Doing something other than that might require separately Lofting the edges in the direction you want them to go.

[TrippyLighting]

@nkloski When such parts are designed there are a lot of considerations that go into the geometry. This is a complex, injection-molded part and a good part of this geometry has been designed to be injection molded.

Depending on what you or your client intend to do with the final model it might not really be necessary to be too accurate.  For example, if this is going to be 3D printed I'd focus on identifying where this interfaces with existing geometry.

However, in case the level of detail is needed I would still work with overbuilt and trimmed surfaces. The new ruled surface command might be of great help for this.

If you are interested in how surfacing works, I can refer you to the Handelbar 3D youtube channel. This gentleman works with Autodesk Alias and while Alias has many sophisticated tools that are not available in Fusion 360 the general techniques can also be used in Fusion 360. 

Another good channel to watch is class A surfacing. That gentleman uses mostly NX and again, a different toolset but the general concepts and techniques are applicable.

Just to make this absolutely clear. Fusion 360 is NOT a Class-A surfacing tool and that is also not required for this and many other parts. I am referring to these channels purely because the techniques are applicable to how you would approach this in Fusion 360.

In general, if more people would use these techniques in Fuoisn 360 they'd be surprised how nicely Fusion 360 can create surfaces.

[nkloski]

Thanks for the great pointers!  @TrippyLighting When you say "overbuild and trim", are you saying to either create surfaces or solid bodies, then use sketch entities to cut away to get the shape?

This is (I assume) in opposition to sketching the "framework" (let's say of the front profile, which is one of the more complex parts), and patching/thickening?

Of course you always use a combination of all tools, but the "overbuild and trim" seems like you still need to define the proper sketch entities...at which time why not just patch/thicken?

Thank you!

[TheCADWhisperer]

@TrippyLighting 

I haven't watched those videos, so I don't know if the topic of why to overbuild a surface and then trim it to shape vs trying to pinch it to shape at the outset is covered - but assuming it is, you might want to give the OP some timesteps  in a particular video to jumpstart the interest in researching the topic in-depth.

(This topic comes up here so often that I need to bookmark a reference.)

[nkloski]

Thanks for the pointers everyone. I did some searching and talking to people, about the over building and trimming workflow.

As with all CAD things, it is a combination of steps which will get you there.  Now that I have that basis, all I am wondering would be where to start with this model?

I'm guessing that the front curve is what I should get first, then all of the more mechanical shapes that  interface with that curve, is that what you all would do?

Thanks!

[TrippyLighting]

Sorry for my lack of response. If you can share the model privately I can demonstrate what I tried to explain in my post in a screencast.

[TrippyLighting]

I created a screencast but it's stuck in upload. We'll see if it can be salvaged.

That screencast only shows the process I followed to create the front surface.

I am assuming some of what is peeking through the surface is not a hard injection molded plastic surface, but a soft gasket that usually seals the interior of the light against the environment.

If I would have to re-create this I'd actually remove that gasket before scanning the part.

With a little finetuning this can be made fit better.

Keep in mind that such physical parts, which likely have been installed in a vehicle for a while and deformed through many heat/cold cycles never reflect the actual geometry in the CAD models they were initially created by. So trying to perfectly match the scan is not needed.

A few test prints might be needed to verify fit.

 

[TrippyLighting]

Here's a screencast of the process that goes onto creating just the front surface:

[nkloski]

Thank you @TrippyLighting very much for the demo workflow!  That helped me!

That raised area on the front is not a gasket, it is just part of the rigid housing.  My final question is, I can get the front curved, even of the raised part no problem using what you have done, and then using an offset plane to trim the overbuild.  It is creating the follow-on surfaces that I have a question on.  

I assume it is a combination of using ruled surfaces and more trimming until the front is done:

and then the more geometric shapes on the back side are more straightforward.  Is the ruled surface tool / trim using offset sketches the main one you would use to create those follow-on surfaces?

[TrippyLighting]

What I was referring to as a gasket is highlighted in red. The rest as you stated is injection molded plastics.

The 

As to the "edge" geometry, I'd thicken the surface and then use an elliptical fillet. 

The question is really, what is the purpose of this reverse engineering. That will determine how accurate you need to be.

If you want to create a very close replica ready for injection molding, then I am not sure FUiosn 360 is the right tool for that. If you are looking to 3D print then a thicken and normal fillet will likely be OK.

[TrippyLighting]

Or are you talking about these surfaces ?

[nkloski]

Yep, exactly!  Creating the front facing surface (now with your help) is completely doable, but I was asking about the connected surfaces at angles to that one.  there are multiple ways to do it:

-ruled surface, then trim with a projected sketch

-Thicken existing bodies, then reference edges to create new surface bodies, which then are thickened

...the problem I have found with the second option is that the thicken command can create gaps where the thickening is not "thicken to surface" but just thickens to normals, leaving gaps.....I am understanding now this is why people "overbuild and trim" to eliminate those gaps.

My question was just on the workflow....stay totally within overbuilt/trimmed surfaces until a final round of thickening, or thicken important parts as you go and build surface bodies off of those?  

[TrippyLighting]

I don't think there is a definitive answer as to what is "the best" workflow.

If my memory serves me well than there was the possibility to create a 3-point construction plane on a mesh, but that seems to be broken yet again. @jeff_strater can you confirm that?

That would make it a lot easier to create these surfaces.

[nkloski]

Thanks!

For creating a plane on a mesh, this way (that adds more entities on the timeline than should be there) works:  Form -> Face with snapping enabled, create a single face -> either use a face edge to create a plane at an angle, or use three points on that face to create a three point plane.