Hi Lara,
is the attached what you need.
Cheers
Barry

Updated Zip.
This gives constant slope length.

YES

Hi Lara,
I have updated the file as I had trimmed the inner and outer diameters and this was not correct.
You only need to trim the outer diameter thus giving a constant slope length.
Cheers
Barry

Hi Lara,
""""""Did you use the cutting cube in one of my previous files? I guess no. Yours has an perpendicular cut. But thats not the right angle...""""""

No. My post was not a solution. I was responding to the post where you asked "why" this was the case and you noted that the opposite sides matched.

I created an illustration to show "why" and how you can't do it with a fillet/chamfer or "winkle"....

Sounds like Barry is bringing an understanding and solution...

That's great Barry, you cracked the code!

So it's making the second cut by intersection with a tube instead of a second planar cut.

- Michael

Sorry if i make an Iso Curve on these slopes (ring2 by Barry) i don't obtain same length ? ...(idem for the second one 1.29...)

There are two 3dm files of interest.
1. Lara's RingCutter.3dm
2. Barry's Ring2 solution. Import this on top of 3dm #1.


To see what is going on, Remove the 4 tops and 4 bottoms of Lara's(Mala's) cutting boxes. Also remove tops and bottoms of Barry's cutting boxes.
The 13mm tube is cut by the 26er cutting planes. (Curve is sort of ellipsoid?)
Barry has swept a 1.3unit radius circle centered on the inner tube cut. It is Rot (RED). (There are 4 red tori_ellip.)
The 15mm tube is trimmed ..... by these red tori_ellip. This cut is DIFFERENT that the cut of the 28er cutter.
The only need for the 28er cutter is to get the initial radius of the red torus_ellip.
(Edit/correction...Barry did do the cut of the 15mm tube with the 28er cutter, as an earlier step.)
Edit see Barry's next post, gif.

So the width of the bevel (winkle) is 1.3 units. Well, 1.3000001 units anyway.

- Brian

........Loft........ the larger and smaller ellipsoid, and a tiny bit more geometry to join the 13mm sections to the trimmed 15mm sections, and the "cones".

The 13mm tube and the 15mm tube remain as large tori, with circular "right angle" cross sections.

Very cool Barry.

Hi,
this is the method I used.(see gif below)
Pilou your correct the iso's are slightly different +/- 0.02 mm but this maybe a display issue.
Cheers
Barry

Edit: Added loft instruction.

Perhaps Barry's small circle sweep could be made to the larger toric_ellip, instead.

-Brian

Hi Brian,
Yes that’s also an option depends on what goes on the 13mm diameters in the finished article.
It’s also possible to start with the 13mm diameter pieces produced with the cutters sweep a given
Slope and length around the ends then use the new edges to sweep the main circle thus creating the larger diameter.
I did an experiment this way but the larger circle is not concentric to the 13mm and not necessarily a perfect circle.
Cheers
Barry

Need to model a further, much simpler version of the ring. I got problems filleting the Ring at the 4 curves at reduced part of the ring. No tricks, just rotated circles and a sweep...

...I made a workaround with 2 lofts and two sweeps. I only want to understand why the filleting failed at sweptAtOnce version...

Hi,

Filetting is only possible on hard edges.
When your edges are soft, it's impossible.

Michael explained it in the 34th post of this forum subjects.

Have fun

It is a sweep with only circles. Do not know why the generated geometry has soft edges.

First create a solid of the larger ring, with its gap.
Second, sweep the small circle to 100% of the gap, and close its ends, to make a solid.
Boolean union the two solids. Result is one ring with smaller diameter in previous gap. Delete or hide the curves. Use the edges to fillet.
Fillet the 4 edges. Total available radius to fillet is 7.5mm - 6.5mm = 1mm,
so the sum of the inner and outer fillets should be at most, 1mm.

- Brian

Hi Lara,

re:
> I only want to understand why the filleting failed at sweptAtOnce version..

Yes like Phiro writes above it's the same answer from earlier in the thread here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=10096.34

Filleting is only possible at edges that are sharp, not at edges that are smooth (tangent) where surfaces meet up.

Additionally, you would need to have an edge between 2 different surfaces to make an edge fillet, if you delete your curves used to generate the sweep you should see that your sweep generated a single large smooth surface.

re:
> It is a sweep with only circles. Do not know why the generated geometry has soft edges.

Because that's how sweep works, if the path for the sweep is smooth you get a smooth surface generated from it. Sweep will only make a sharp cornered shape in places where the path curve also has sharp corners in it.

- Michael

Hi Pilou, How did you get that shiny material preset for your objects in MOI?

@Subroto

Take a look at this thread ;)
http://moi3d.com/forum/messages.php?webtag=MOI&msg=5222.47

And sometimes before send the image i make some corrections colors in any 2D prog
mine is an very old one (more 20 years old : Photo impact 6 :)


If you want a free cool one for some drawing/painting effects take a look to the free FotoSketsher (made by a French guy! ;)
https://fotosketcher.com