Path Bevel Way Too Big

I am trying to create a simple wire, with a length of 80, and a thickness of only .017 (Blender units). To give the wire some droop between the two ends, I created a simple parabola, using a bezier curve. I then wanted to use a low-poly bezier circle as the bevel object. For some reason though, the bevel comes out way larger than the circle.

Here are a couple screen shots, that show the objects and all of the settings. In this first image, the circle is selected, to show all of its settings:

In the second image, the bezier path has been selected, and the circle has been chosen as the bevel object.

But, as can be seen, the resulting bevel is over 10 times the size of the circle (the dark area is the open mouth of the resulting tube). Does anyone know why this is happening? The tube should be the same width as the circle.


No one else has encountered this?


Well, I managed to fix this problem. In my first attempt, I started with a short curve, so that I could see the shape of the droop. I the used scaling to stretch the curve to the length that I wanted. That scaling may have caused my problem, even though I used ^A to set the new scaling to 1.0. Have i discovered a bug? Here is what I should have gotten the first time:

Maybe you have set “mean radius” much larger than 1.

Thanks. I did a search on “mean radius”, and I found that I shouldn’t have tried to scale the curve. It apparently causes all kinds of problems, that control-A just can’t fix.

You didn’t ask, but:

Catenary: f(x) = a + (1/b)cosh(b(x-c)), where a, b and c are constants.

Here is a great pagethat figures out a, b, and c for you.

Overkill? Maybe. Somehow substituting parabolas always looks just a little wrong to me.

Thanks for the heads-up on the catenary. I had forgotten the formula, and now I see why. Is there a way to plug formulas into Blender curves? But, in reality, my curve was neither a catenary nor a parabola. It was just a three-point bezier, that I used to approximate the curve. Seemed to work OK, to render this scene:

The bottom pic is just a slightly off-center ortho view, that I used to tweak the material of the wires.