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 From:  billis
1175.1 
please can anyone help me to create this ring(only ring not the stone)
thanks basilhs

EDITED: 14 Feb 2008 by BILLIS

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 From:  Frenchy Pilou (PILOU)
1175.2 In reply to 1175.1 
@billis ???
It's exactly my previous tut!
http://moi3d.com/forum/messages.php?webtag=MOI&msg=1151.1
Som problems in what aera?
---
Pilou
Is beautiful that please without concept!
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 From:  Michael Gibson
1175.3 In reply to 1175.1 
Hi billis - this one looks pretty similar in shape to the one that Jesse did in this tutorial:
http://moi3d.com/forum/index.php?webtag=MOI&msg=510.5

If you open up the file that Jesse attached there, you will see several different stages that went into making that ring.

It will take some different steps to create this ring than the previous one that you posted - you can't just combine 2 straight profiles to make this one since that will create a kind of block type shape and you want a smoothly curved shape here.

Just like in Jesse's steps, you will not want to model the finger hole directly at first - at first just concentrate on making the outer shape as one whole piece and then drill the finger hole in later.

I believe Jesse used Sweep to create his outer shape - that gives you a lot of control over the shape since you can put in a number of profile curves to control it.

In your case, Rail revolve might be a good option for constructing the outer shape, see here: http://moi3d.com/1.0/docs/moi_command_reference7.htm#railrevolve for some examples of Rail revolve.

Rail revolve pivots a shape around an axis similar to regular revolve, but you can also supply a path curve that squishes the shape. I think in your case supplying an ellipse as the path curve might work pretty well.

To start with I drew these 2 curves in the Front view:




Then I switched to the top view and drew this ellipse:



I then dragged the ellipse upwards so it was near the of the shape. It's actually ok if you leave the ellipse down below though. So at this point I have these curves as seen from the 3D view:



I then selected the profile curve (shown in yellow above), then ran Construct / Revolve / Rail revolve (rail revolve is the second option to the right that comes up under Revolve). Then select the ellipse as the rail curve, and pick the axis in the front view, first point at the bottom end of the profile, and second point vertically up from it. That will create this shape:



Now select that shape, and then run Construct / Boolean / Difference, then select the circle as the cutting object. That will drill a hole through your shape and leave you with this:



It might be a good idea to then select the edges around the finger hole and apply a small fillet to them.

You can edit the profile curve to control the general shape of the ring, including how much it flares out at the top.

Model is attached here as rail_revolve_ring.zip

Hope this helps!

- Michael

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 From:  billis
1175.4 In reply to 1175.3 
thanks michael is very usefull ur tutorial, but in this way i can control the down part of the ring.it depends from the distance of the circle or elipse.can u show me a way that i control the distance?(if we see the ring from the right side to make for fat down and the elipse be the same)sorry for my english i dont now if u understand me.i have ty after the rail to do that with control points but they dont work.please help me
thanks basilhs
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 From:  Michael Gibson
1175.5 In reply to 1175.4 
Hi billis, I'm not sure if I completely understand, but I think that you are looking for a way to have more control over the width of the ring near the bottom part.

The method that I showed there using "Rail revolve" uses the fewest possible number of curves. That makes it also the easiest to set up, but with a smaller number of curves also comes a sacrifice in the amount of control.

There are other construction tools that you can use instead of Rail revolve that will let you specify a larger number of curves which will give you more control. However, these tools are also more complex and may take more practice and time from you to learn how to use them.

The 2 main tools that you would use in this situation to gain more control would be either Sweep or Network, I would focus on Sweep in this case.

To use Sweep you need to have 2 "rail" curves that act as a guide to slide the curves along. So in this case, I copied what used to be the revolve profile over to the other side to make the second rail:




The basic shape of the sweep will come from the ellipse at the top traveling along these 2 rail curves.

To gain more control I will use an additional profile that I draw in the right-side view, like this:



This additional side profile will be applied to the sweep using the "Scaling rail" option - this will cause the sweep to stretch out or shrink down so that it conforms to that additional profile. By adjusting this profile you can gain a lot of additional control over the shape.

You should now have a set of curves that look like this in the 3D view:



To perform the sweep, start by selecting the ellipse at the top - this is the profile curve for the sweep.

Next, run Construct / Sweep. The prompt in the upper-right corner of the screen will say "Select one or two rails" - select the 2 rail curves and push Done (or right-click inside the viewport which is a shortcut for Done). The basic sweep will now be displayed:



You can see that it is currently quite similar to the rail revolve. Now before you exit the sweep command, you want to apply the scaling rail to adjust the shape to conform to your additional profile. To do this, push the "Pick scaling rail" button circled in red above, and then click on the scaling rail. The sweep will now update with the additional profile applied:



You can now push Done (or right-click) to finish the sweep. You can now edit the control points of the scaling rail to adjust the shape some more, the sweep will update if you edit any of those curves that went into it.

For example here I have edited the scaling rail to make the shape quite narrow:



It is also possible to use more than one profile in Sweep as well, like you could place additional ellipses coming down from the top one and use all of them. But the scaling rail usually takes the place of drawing in a lot of profiles.

When you are done making the base shape, select it and use Construct / Boolean / Difference to slice the circle out from it just like the previous example, shown here with fillets also applied:




I attached the .3dm file with the curves in it here as sweep_ring.zip .

Also check out Jesse's tutorial here: http://moi3d.com/forum/index.php?webtag=MOI&msg=510.5 , which goes through a similar type of setup.

Hope this helps!

- Michael

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 From:  billis
1175.6 In reply to 1175.5 
michael thank u so much.with this tutorials i can fix a big category of rings
thanks again.if we dont talk again soon mary cristmas and happy new year
i hope u help me again
basilhs
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 From:  Colin
1175.7 In reply to 1175.1 
Hi Basihs,

Here's a ring blank based roughly on the photo you supplied.

First I created a circle at 9mm Radius for the finger size.
I then created the ring Profile then used Rail Revolve as Michael has already suggested.
I then switched to the Right View & created two arcs then Joined them to form a closed shape.
While still in the Right View this new closed shape was Mirrored to the opposite side of the ring.
Still in Right View select the ring, click Boolean Merge & select the two closed shapes.
Delete the two sections that have now been cut from the ring.
Select the inside circle(finger size) & Extrude it with "both sides" checked.
Select the ring, click Boolean Difference & select the Extruded inner shape.
Select the ring again & click on all the outer edges of the band on both sides.
Click Fillet & enter 0.7mm.

That's it, but you'll still need to create the settings for the Diamonds & the centre stone.

Hope this helps, Colin
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 From:  Michael Gibson
1175.8 In reply to 1175.7 
Hi Colin, I think I like your way better.

I was worried about making a straight cut like that possibly resulting in a blocky type shape. However, it works great when the straight cut is applied to a rounded base shape. The blocky type problem that I was worried about happens when you apply the straight cut to another straight-punched out (extruded) base object instead of a rounded base object.

And actually the hard edge that is introduced with your method is actually an advantage.

With your steps, you get this shape at one stage:



Which actually is nice because then filleting the outside edge lets you have a hard inside edge, and then a more tightly curved outside edge. That kind of seems like a more expected form around that area.

Actually with the sweep method you can get this style by first applying a wider chamfer along that single edge (the sweep method starts with just one edge around that finger hole), which will construct that straight bit for you, then round the outside edge of the straight part.

Anyway, I am still happy to have the sweep method documented above, it is always good to have more than one approach available for constructing things, sometimes when you want a particular kind of different style it can be easier to apply it in one method or the other.

A couple of small notes on your steps -

When you create the cutting pieces from the right-side view, it is ok if they are not closed, they can be open as long as their profiles cross the whole object and appear to fully divide it into 2 pieces.

You can also skip the extrusion of the circle - just select the circle curve as the cutting object in the Boolean difference. The boolean will do the equivalent of Extrude with "both sides" for you automatically.

billis - let me know if you need any additional illustrations for Colin's steps.

- Michael
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 From:  Colin
1175.9 In reply to 1175.8 
Hi Michael,

<Hi Colin, I think I like your way better.>

The basic idea for doing a ring this way came from one of the guys on the 3dcadjewelry Forum.
This was his suggestion on how to make a Signet ring or School ring really simply.
I just figured I could use the same method to construct a ring similar to the photo.

<When you create the cutting pieces from the right-side view, it is ok if they are not closed, they can be open as long as their profiles cross the whole object and appear to fully divide it into 2 pieces.>

He's using Rhino, so I think that you might need to create a closed curve for it to work correctly in Rhino?
So I just started using the same basic construction method in MoI & it worked great, so never thought of doing it using an open curve?

<You can also skip the extrusion of the circle - just select the circle curve as the cutting object in the Boolean difference. The boolean will do the equivalent of Extrude with "both sides" for you automatically.>

Ahh!, Great Tip!! I've been so used to doing it the Extrude way that hadn't even thought of doing it like that?

regards Colin
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 From:  Michael Gibson
1175.10 In reply to 1175.9 
Hi Colin,

> He's using Rhino, so I think that you might need to create a
> closed curve for it to work correctly in Rhino?

Yeah probably - Rhino isn't able to do booleans mixing solids and curves directly like MoI. So using Rhino you would probably make those closed, extrude them with "both sides", and then use boolean difference using the extrusions as cutters.

Rhino does have a separate "WireCut" command that will cut a solid by a curve (the curve can be open), but it seems to only work using a single curve cutter at one time, so you would need to repeat it 2 times to cut this object.

- Michael
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