How to extend and flatten a closed polysurface


Hi all,

I have created essentially a curved cylinder by using the Rail sweep 2 function. I drew two curves, and then drew circles in between the curves. (I don’t know if this is the most efficient way to do this, but I new and still learning Rhino; I might have been able to create a cylinder and bend it?). I put caps on the end to create a closed polysurface.

I want to extend, flatten and widen one of the circular edges into a very thin rectangular shape and attach it to a another object (basically a thin rectangle). How can I accomplish this?

I know that with closed surfaces, I can manipulate individual points to to extend, flatten and widen, and then bend and join the objects together, but how do I do this with a polysurface? Or is there a way to convert the polysurface into a closed surface or a solid?

Thank you in advance.

(David Cockey) #2

“Close surfaces” and “solids” in Rhino are surfaces or polysurfaces which are closed without any naked edges.

Other ways to create a curve cylinder:
Use the Pipe command
Sweep a circle along a rail at the center of the circle. The curve being swept does not need touch attached to the rail curve.
Create a straight cylinder and bend it using CageEdit The cage can be as simple as a curve which starts out straight and is bent into the desired shape. I’d use one of the other two methods for a simple bent cylinder but CageEdit can be very powerful.

For the circular cylinder which transitions to a very thin rectangular shape at one end I’d use Sweep1 with multiple cross section curves. OrientOnCrv can be useful for locating and orienting the sectional curves. Draw the sectional cuves on a construction plane. Then move/copy them to the desired locations using OrientOnCrv with the Perpendicular option. The base point can be off of the curve being oriented. In the attached example I used the center of the curves as the base point.Distorted Cylinder Example.3dm (192.1 KB)