topic Re: Some geometry destroy with the fillet command in Fusion Design, Validate & Document Forum

Some geometry destroy with the fillet command

summerson1990 — Wed, 08 Dec 2021 09:51:32 GMT

Hi! Could you please look at my design attached? I can't understand why I'm getting here shown in the screenshot vertices out of the planes a little bit according to the XYZ measurements. Also if you look at some closer you'll see here are at right 2 vertices (near start measuring point "1").

It happens after the fillet command is applied. I've rolled back the timeline and checked each step and can't find the reason for it. Where have I made a mistake?

Thanks!

Re: Some geometry destroy with the fillet command

TrippyLighting — Wed, 08 Dec 2021 12:03:31 GMT

There is no "destruction" of geometry 😉

The geometry is quite a reasonable result of your modeling approach, with is distinctly different in at least one key aspect, from what I demonstrated in the earlier key cap design we worked on. I'll demonstrate that later, possibly in a screencast.

Re: Some geometry destroy with the fillet command

rohit.bapat — Wed, 08 Dec 2021 12:17:48 GMT

Hello @summerson1990

This is a very strange issue. I tried to trace back the steps as well and I found an issue just after offset surface feature as shown in the following image. Now, I don't know whether it has any effect on the final result though. I will forward this to the development team so that they can investigate it further.

Delta XYZ don't show that the points are slightly misaligned

We will update once we find some reason or the solution to this issue.

Re: Some geometry destroy with the fillet command

TrippyLighting — Wed, 08 Dec 2021 12:29:07 GMT

The additional vertices and edges in the design of the keycap, highlighted in red

Are a result of 2 things:

1. Sketch #3 defines tangency between the arcs and the line. That is also exactly where the tangency edges in yur base-key cap appear:

And those will then also appear in the fillets. They have to for the geometry to maintain integrity.

2. You are lofting between a planar and a curved profile. In my key-cap version I lofted between 2 planar (but not parallel) profiles, which results in a much cleaner loft. Then I trimmed out the curved top of the keycap.

I also would recommend you keep the fillet on the top edge separate form the variable fillet.

Then you can make it a chord fillet to get a better visual result. This might not matter for a keycap due to it's small size, but it doesn't hurt either 😉

Re: Some geometry destroy with the fillet command

TrippyLighting — Wed, 08 Dec 2021 12:30:39 GMT

@rohit.bapat wrote:

Hello @summerson1990

This is a very strange issue. ...

We will update once we find some reason or the solution to this issue.

You do that, while I recommend a better design workflow, which completely avoids the issue 😉

Re: Some geometry destroy with the fillet command

rohit.bapat — Wed, 08 Dec 2021 12:33:24 GMT

Thank you @TrippyLighting 🙂

I believe the given workflow should have worked. I hope the solution makes our tools more robust.

Re: Some geometry destroy with the fillet command

summerson1990 — Wed, 08 Dec 2021 13:00:52 GMT

Thanks, Peter! Yes, it would be great if you show your workflow in a screencast for this design 😉

Re: Some geometry destroy with the fillet command

TrippyLighting — Sat, 11 Dec 2021 19:06:49 GMT

Here's a screen recording that explains why these extra tangency edges appear and why I think there is no bug to be discovered and nothing to be made more robust. The HD versions are still converting as I post this:

Re: Some geometry destroy with the fillet command

summerson1990 — Mon, 13 Dec 2021 12:14:07 GMT

Peter, thank you again for the screencasted workflow and all the detailed and deep explanations! 😊