# How can I control the size (Diameter) of a ring that is made with the simple transform / Bend?

I start with a 1 x 1 x 1 cube set at -9.5 Y units from the origin. I use an empty at the origin as my Center of Deformation. I use the simple deform modifier / Bend with 360 deg as the deform parameter. The resulting radius of the ring is about 10.159 and the diameter of the ring is about 20.318. Yes, I can scale the ring in X and Y back to the desired Diameter=20, and recenter the ring at the origin. But this introduces a slight error in the inside diameter of the ring that is a challenge to correct.

Is there any way to predict what this dimensional difference is before I begin and adjust for it in either the mesh center, cube size, Center of Deformation, or anything else that is predictable?

The Bend Deform is simple, but the outcome is imprecise. Is there a more precise way to construct the ring?

• Apr 27 '18 at 0:26

Different, slightly quicker approach -

Add a cylinder and change the radius and depth in the last operator panel to match the desired values:

Then in edit mode, select the top and bottom faces, extrude in place (press E, then immediately after Enter before the faces had a change to move anywhere), then change the pivot point to individual origins:

Now scale the top and bottom faces to match the desired radius. Since we change the pivot to individual origins, each face will scale around its own origin, and in effect both faces will be inset.

Now the only thing left is to bridge the two faces to create the inner hole and geometry (see answer above to explain how to activate the looptools addon if youre not familiar with it):

• ~~ Both of your modeling methods are easy to follow and I appreciate the precision of these models. I wanted to use the Bend modifier because I could assign the materials and textures to the six faces of the cube before subdividing it and bending it. This gave me a work flow that simplified the UV unwrap. I will be working with your suggestions and see how the UV unwrap works out. I am trying to achieve the appearance of wood that has been bent with only one texture that goes onto each of the faces. Aug 21 '15 at 14:28
• The UV unwrap was flawless and simple on the model I made with this method. Many thanks! Aug 21 '15 at 16:33

In your approach, you can generally scale the inner and outer rings separately in edit mode. It's tricky to measure the selected elements' dimensions (I have an addon soon to be released for that) but possible, if cumbersome.

However, you can generate a precise ring with a slightly different approach, based on adding mesh circles.

First add a circle, then set its radius from the last operator panel:

Then go to edit mode, and add another circle, which will be part of the same mesh since you're in edit mode. If the first circle was our inner right, this is our outer ring. Again set its radius to the desired outer ring radius from the last operator panel:

Now you can use the looptools bridge to connect the inner and outer ring. If you don't have the looptools activated, add them from the plugins menu in the user preferences:

And the last phase would be to extrude the rings to the desired height:

• I really appreciate these instructions and will practice it for the sake of learning the steps to modeling such a well controlled mesh. These steps result in the precise geometry I am looking for. Aug 21 '15 at 14:15