Merging two cylinder forms into a symmetrical figure 8

[andholt]

Hi folks! I'm in the process of trying to model something using forms, which requires a perfect "figure 8" as an outline. I want two perfect cylinders to be merged into one shape per the image below, and be able to creating mirror symmetry for both the length and width.

While I can manually draw all of the faces as one form, that's somewhat laborious and I can't figure out how to ensure a perfect circular shape for each half. So, I've tried creating two cylinders and manually inserting edges where they meet, then merging the edges. However, since I'm just eyeballing where they merge, I can't get symmetry to work since the resulting figure 8 is not perfectly symmetrical.

Is there any way to merge two cylinders as one form body that is symmetrical?

I've attached my file with just the two cylinders (not the manually inserted edges where they overlap since that doesn't seem like the right approach). Thank you in advance! 

[TrippyLighting]

It isn't clear by your description and the image what exactly you want. I start with this:

[andholt]

Hi Peter, thanks so much for your help. Apologies for not being clearer – I'm trying to combine the two cylinders but keep only the "outer" walls, so to speak. Like so:

The issue is I'm doing this by manually inserting edges where the cylinders overlap, and then merging those edges after deleting the inner walls. This works visually, but I lose symmetry and can't then mirror in this direction (this throws an error):

My goal is to have the above form with symmetry in both directions, since I'll start building more faces inside the form to build a sort of bowl. There may be a different way of constructing the outer walls altogether and my approach isn't correct, but not sure where to start. Thanks again!

[andholt]

Just figured this out myself – I'm new to Fusion and didn't realize you can start with a sketch profile in the Form editor. I created a sketch, create two overlapping circles, and trimmed out the inner lines. Then I extruded that sketch to get the walls of the object (and added symmetry in both directions). 

@TrippyLighting thanks for your help - I am curious how you made the form you shared.

[davebYYPCU]

Why Forms, with symmetry, to date there is nothing can’t be done as Surface model.

Might help…

[andholt]

My goal is to make a somewhat organic object (no hard angles except for the vertical sides) from this that can be 3D printed as a prototype and later injection molded. I don't have exact measures going in – I need to play around with the angles, 3D print, and then iterate. From what I've gathered, forms will make this fairly easy?

[TrippyLighting]

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@davebYYPCU wrote:

Why Forms, with symmetry, to date there is nothing can’t be done as Surface model.

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Yes, so far, maybe no T-Splines are needed. But ... 

1. It is always a good idea to start with a simpler object to get the hang of T-Spline modeling.

2. Sometimes, form exploration is vastly quicker with T-Splines.

3. Sometimes, I start with symmetry to get a base shape down and then break it for the final model. Try that with a surface model 😉

[TrippyLighting · Accepted solution]

Here is a screencast of how one can develop the #8 shape I posted in my first reply

[andholt]

Awesome, this is great! Thank you so much.