Hi
Please advice how to get this nice and smooth shape like this (without the red part)?

Regards
Olga

Hi Olga, if you have the 3DM model file if you could post that as well it would probably help to see how it was constructed.

But it looks like the shape there is trimmed from a larger smooth surface.

It can often be easier to make a smooth shape if you make a larger extended surface and then cut it.

I think that one of Jesse Kaufman's tutorials is similar to what you are looking for there:

http://moi3d.com/forum/index.php?webtag=MOI&msg=510.5

- Michael

Hi Michael
I know this lesson and studied it but in my example the oval is perpendicular to finger so the sweep is easy to do.
In my example (it is not a 3dm file it is just some screenshot from somewhere)
I am trying to make something similar and just cannot get it right.
Please find attached the file

Thanks
Olga

Hi Olga, well for the most part your ring is looking pretty good.

Like for example the bottom part here:



That seems to be looking good, is that part how you want it or are you trying to do something different in that area as well?

It looks like your problem is a wiggle in the top part. Probably the easiest way to avoid that would be to cut things off so that you don't try to build the upper part all in the same sweep as the other parts.

Note that in Jesse's version the curve framework terminates at the top area:



If you do the same with yours it will probably give you a better shape at the top and make it like the image you posted.

It looks like the wiggle in the top for your case is caused by the inclusion of this profile:





That profile is some distance away from the rail, so it causes the sweep to flare out at that spot, creating the bulge in that area that you don't seem to want.


Sometimes when you get bulges like that it is an indication that you're trying to apply too much pressure on things during a single surface construction. Sometimes when this happens it is good to try and reduce the amount of stuff that you are trying to build all in one shot, and try to make some parts as separate pieces instead of all at once.

- Michael

Thanks Michael
Please notice I would like to have a ring that on the side would look like that




I used yellow as a scaling rail.


But when I extrude the circle for finger hole this is what I get. So the side view changes dramatically from what I initially wanted.



So I cannot put two and two together.

Can you advice

Thanks
Olga

Hi Olga,

Here's a quick & easy way to do basic type Signet bases that I was shown by a Matrix/Rhino user.
I've found that sometimes for certain shapes you can use Sweep, but Rail Revolve is the better option.

In this case I'm not sure it'll produce the exact results that you're after, but it might give you another option to work from?
Hope it's of some use, Colin

Hi Olga, normally sweep expects a smooth scaling rail, not one that has sharp corners in it, so that is probably not going to work very well as a scaling rail in what you show there.

Could you please post a 3DM model file to go along with the images in your last post?

Your original file has a different shaped result in it, and there are quite a few curves in there so I'm not immediately sure which ones you have used for the construction, like which ones were the rails and profiles, etc... If you can post something more simplified that for example only has the curves you were using for the last images that you made, that would help me to follow what you are doing.


> But when I extrude the circle for finger hole this is what I get.
> So the side view changes dramatically from what I initially wanted.

It seems like the shape is too narrow in that area - when you apply the scaling rail, it controls the outermost profile of the generated surface. But you are actually trying to control the profile of how it intersects with the extrusion of the circle which is not the same thing.

It looks like the shape is too narrow in that area to get you the final result that you need, so I would think you would want to make the scaling rail wider that that, to stretch the shape some more in that area so that it will get you the result you want after intersection.

Or possibly instead of a scaling rail another profile or two in that area may help to control the shape and widen it a bit there.

It can be difficult to control something in multiple directions simultaneously.

If you can post a file that lets me re-create the sweep in your last posts though that would make it easier to try and help you.

- Michael

Hi Olga, also I don't understand what you are doing differently between the first file you posted and your second one.

It looks like the first 3DM file that you posted seems to have the side profile you want, when I open your attachement 1626_RainCabRing2.3dm, I see this:




That seems to have the side profile you want, and it also has a hole in it for the finger already, so isn't that the shape that you are talking about in your later message?

- Michael

Hi Olga, I guess I see that it is not quite right in this area:



But it looks really close in other areas.

I would think that you would use the same technique you used in this model, but put some additional profiles but try to make some adjustments.

Terminating the curve structure at the top should help to avoid the upper part kind of bulging out.

For example, instead of having the rails continue, cut them to make them stop at this location:



If I knew more about how you constructed this model it would make it easier to help.

Maybe I don't understand, but it looks like this is already close to what you are asking for, so I'd think you would want to use the same method you did here but make some adjustments.

- Michael

Hi Olga,

Maybe try this version & see if it better suits your needs?
Combination of Network, Sweep & Trim

regards Colin

Hi All,
I had a go at this and took a different approach, I not sure about the proportions, it's the quickest and easiest way I could think of, jewellery isn't really my thing.
Hope it helps.

Patience needed, it's a pretty big file.


Download link: http://cid-30cffdfa97399495.skydrive.live.com/browse.aspx/.Public

-

Hi Olga,

Here is my try.
I didn't get a solution for the top part,but i hope it will help you.

Here's mine. I didnt get the top right either. Forgot to sonsider this area in the initial creating phase. I suppose I could revisit the beging and try to start all over :O

Well THAT was an utter failure!!!!! :O

I just reviewed it an switched to front view. Oooops.

Here I reworked it to what I think is a ring, Though since I reworked the buggered up file I posted, I lost some mass around the lower portions. I believe this is the shape in the picture though....I suppose I may revisit this after a few beers tonight to see if I can get it right. (Seems I always miss some "very small insignificant" design detail like the "FINGER HOLE")

Ok, 1 beer and it looks a bit better!

Here's my approach.
The main surface is a network between the top ellipse and the four side profiles.
Then it's trimmed with the two side arcs to make the finger hole.
The edges are blended together using the 3 small arcs as profiles to ensure continuity. Notice that in order to draw these 3 arcs I used 3 pairs of lines perpendicular to the side edges and then I blended them with G2 continuity.

The file contains all the curves used as well as the final shape.
Cheers
Dan

Hi Daniele,

Good idea :)

Nice work Guys!
Very educational for all, love seeing the different approaches on this, we should do it more often.

Cheers

Cant let it go for some reason. Here's a shot at a different method I tried to think about. Legend included.