Hi there. I’ve been using Rhino for a few months now and have got considerably more comfortable with it. I have a project I’m currently working on and I’m trying to figure out what the best method of creating this last polysurface would be. (see below image).
The problem I’m having with this surface is at the corners. It extends out past the top, and when trimmed away it leaves a gap that is difficult to fill. What techniques/commands should I use to create this surface?
Create a curve from the bottom edge of the top piece.
Split the curve at one corner using the two outer vertical curves.
Use RailRevolve with one of those verticals as the Profile, the split quarter circle as the Rail and the bottom end of the vertical curve as the start of the Rail Axis. this will give you one corner surface.
Create the remaining corner surfaces by using Mirror.
Create the straight side by using Sweep1 with one of the straight top sections as the Rail and the adjacent corner surface edges as the Profiles. Repeat for the other three sides.
You will be having a hard time with surfaces and highlights if the input curves are not alright. For example, I manually recreated these curves as 5-degree splines in the top screenshot.
Thanks so much! I knew there was a better way of doing it. Never thought of using rail resolve on small sections before, or using it for the corners, very good technique to keep in mind.
I did try to trim the corner back and recreate it with a new surface. However, I ran into some weird issues while doing so, but I see you got it right so I should probably give it another attempt.
As for my curves I created them starting with points and then creating a curve between them. I imagine that those kinks are where my points were. I never realized that doing so would still leave kinks. When it comes to curves Im still learning alot and im not entirely sure how I can prevent this or perhaps rebuild them to remove the kinks, but this could explain the various troubles I’ve had with creating surfaces.
Could you perhaps explain a better way to create curves or a way to rebuild them so that this will not occur?
In my example I just drew a new straight line to top of your S-shaped curve (from start to end). After that I changed the degree of the new line to 5 with the ChangeDegree command. And then just manually control point edited the new curve as close as possible to your curve. To control point edit a curve, you’ll need to turn on the control points (of the curve) and then just move them around.
This was harder than it looked at first glance. I tried isolating degree 1 curves, to try figuring out your design intended radius on the upper flange, but I had to give up because it turned out to be too dynamic, and Rhino doesn’t have an easy way of creating an arc tangent to two curves and coincident to one point – neither does GH, from what I could tell.
So, turns out there will be kinks associated with your original curves and how they match together over all.
Therefore, there’s much interpretation going on to attempt to quantify over all design intent in the end.
