Hi, I'm fooling around on a 3d Model in AutoCAD and I need some 3D

geometry help to solve a solids-editing problem.

I need a shape, that used as a section when passed through a cylinder

would result in a constant change in z (height) from the perspective

of the arc perimeter.

For example, assume we are looking at the top of a cylinder and a

wedge, side by side. Using the top of the wedge as a cutting plane,

we move the wedge to the right along x through the cylinder. (The

highest part of the wedge is toward the top of the y axis.) The

variation of delta z (height) on the newly cut cylinder perimeter,

varies with its least rate of change toward the middle of the

'circle'.

To create a constant drop in z along the perimeter of the cylinder, I

think I should be able to determine the math of an 'S curve

wedge' (again with the highest z toward the top of x) that can be used

as a slicing plane to be applied to the cylinder. The middle of the

'S curve wedge' would be less steep to cut a shallower profile through

the middle (fro a top-down y persepctive) of the cylinder.

I'm rusty on this math. Help? I could post a diagram...

Rocco