imagine a gear set with one gear fully formed and the other just a disk. Now rotate the gears about the centers (in opposite directions) and have the profile of the first gear machined (or formed) into the disk so that it is an exact match with the first. The shapes don't have to be gears but that is the best example I could come up with. You should be able to do this with a triangle, square or any shape so that when rotated it forms a meshing shape on the plain disk.
your problem is more general, then I'll try to help. I don't know the "buzzword" for this, I call it "inverse CAM" because you want to obtain a cad model out of a (simple) "manufacturing" process. It is definitely not a simple problem, so I'm working on it ;-) In the general case you'd have to do a loft cut of the "tool" profile along a path. Our "MathSurf" add-in can help if you have mathematical equations of the profile(s) and path, which is the hard part. Have a look at
for an example. In your specific case, and as long as the axis of both your cylinders are parallel, you only have to generate one curve. I didn't go into this in detail, but "involute curve" is the term that comes to my mind. Send me more details (or even models) of what you want to do and I'll try to help you more.
"Tim" wrote in news:b3Neb.166533$ firstname.lastname@example.org:
To me it sounds like you want to rotate both gears and make one gear cut the other.
If you only rotated one gear, you might be able to do this with a loft, using the faces of the gear as one profile, and copying the faces to a finishing position with arc guide curves (even simpler if you could do a revolved cut).
If you need to rotate both gears while making the cut, it becomes more complex. The lofted cut path becomes the added motion of one gear around one axis plus the motion of the other gear about the other axis. I don't believe you can accomplish this with a simple technique in SW (like projected curve). I think to get the path, you would need to write an equation that maps the motion of one part which is rotating when viewed from another part that is rotating on a perpendicular axis. Once you get that, the SW website has a macro that will plot points on a 3D curve to make a spline. You can use the spline as a guide curve for a lofted cut.
...or you could just break down and buy the Camnetics software that has the gear profiles all figured out.