Curved Tapering Profile

[Anonymous]

I'm trying to replicate some elements from a book cover of mine as 3D models for a potential 3D printing project. The image is below.

Now, for the gem part, I'm pretty happy with what I've got. But that curved tapering bit is a real pain. I tried a sweep, but it's a non-uniform width, so if I use scaling the thickness isn't a smooth decrease, and I can't get it to go to the very end without erroring. Next, I tried a loft from a starting profile in the center to the point at the end of the curve, but again, the non-uniform thickness means just using a center-line makes it too narrow to match the image. I created an angled plane through the endpoint and the top of the profile, and then used three curved rails to shape the loft, and it got SUPER close, but there's a weird wrinkle on the top of the curve.

Any thoughts?

[HughesTooling]

You might be able to get what you want with extrude tapered, see attached file.

[HughesTooling · Accepted solution]

You might be able to get what you want with extrude tapered, see attached file.

[Anonymous]

That does come super close. Certainly close enough to satisfy me, but in my instance the tool body fails to create if I complete the taper entirely. As you can see, there's the tiniest of top surfaces on mine. I may be able to deal with that just by tweaking the original profile slightly. Thanks!

[TrippyLighting]

This should be dead simple to do in the patch workspace.

Maybe the screencasts I created in this thread can give you an idea as in general the problems are very similar.

[Anonymous]

That works exceptionally well too, though there's a tiny little "weird wrinkle" on the inside curve where the shape bulges out a little. It's super small, but you can see what I mean in the cross section analysis, where it's convex rather than a straight line.

Do we know what causes that sort of thing and how to mitigate/avoid it?

[davebYYPCU]

I think the loft tool has a tendency to stretch it's result, and the profile is being "pulled" to the inside of the curved rail,

I have done it with this file the way you are looking for, straight sides, same curves as the canvass,

(had a little drama with one sweep, had to delete half of the model, and have to mirror now,)

Might help .....

[Anonymous]

Oh, wow. Interesting solution. Clearly I have to get a little more familiar with patches.

[davebYYPCU]

Yeah, Patch is a little more forgiving, but more work - if you get what I mean.

Did it this way, to allow for varing height on the middle rail  just a bit, the centre profile is lower than at the middle section in front view.

Happy to help,  

[TrippyLighting]

The thread I inked to has two screencasts. In the second one I am not using the loft tool.

You can simply create a patch!

If you don't want a "flat" patch, because for example you might want the shape to be scalloped (concave) or cupped (convex) you can simply use a loft with rail, which will provide predictable results.