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Matching surfaces Problem


New member
Hello All,
I am running v4 an I am trying to draw a dragbike frame. I have the wireframe complete and am trying to "flesh it out". This fleshing consists of pushing a circle along a control line to create a surface that simulates a tube.
The poly line, in it's finish state, has radi at the bends to represent a tubing bender radius, typically 3" centerline.
I tried doing this with a polyline but the plane of the circle doesn't change and when it goes around a corner, and the tube flattens out.
I tried spliting the polyline into idividual curves and doing the extrude piecemeal. This had some success with the minor bends in the tube in that I can trim one to the other and get the common surface edge.
On the major bends, this plan fell apart. There seems to be not enough overlap at the corner to allow matchsrf to undestand what I am trying to do. The 2nd surface wireframe "cones" and otherwise becomes distorted. Intersect picks the wireframe lines as they were created between the 2 surfaces and creates a very weird polyline that is not usable to me. I cannot, as far as I can see, pick the lines individually to create the proper intersect to cut the surface.
I do not understand how to orient the surfaces so they match so intersect can do it's job and I don't understand what matchsrf wants to trim the two surfaces at a common end line.
Please understand the I am going to want to add a filet or curve into this poly surface to show the bend radi and I am not exactly sure how to do that either.
I know my nomenclature is alll over the place in this post but I am not familiar enough with Rhino to know the right words.
Thank you for your time, Rick