# Geometric Calc Help

• Feb 4th 2008, 07:36 PM
Rocco
Geometric Calc Help
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