Better way to sweep

[Tommy804]

Hi, I does anyone know a better way to model this profile in rhino with out getting the bunching around the bends and at the ends. Currently using Sweep1 to make this surface

[jeremy5 (Jeremy)]

Sorry, but it isn’t clear from the image what you mean by bunching. Please export the curves and the surface into a new model and post it here. I’m sure someone will be able to help you then.

Regards
Jeremy

[Tommy804]

Sweep.3dm (533.2 KB)

[Brenda]

Hi @Tommy804,

Like a minimum bend radius for wire or pipe, the radius of the spline-curve is too small/tight for the diameter of your cross-section curves. That is what makes the kinks kinks that you have. If you make the radius larger, the surface won’t go back on itself.

Going further, you have few more nodes on the spline-curve than you likely need. Generally, with curves, NURBS, and even SubD the fewest nodes to do the job makes the smoothest surfaces.

I would also join the curves before the sweep as well, perhaps matching them as well.

[jeremy5 (Jeremy)]

Hi @Tommy804,

A lot depends on what effect you aim to achieve. What’s your intent for the treatment here?

and here?

[zhuangjia777]

Pipe Corner Clean

This plugin may help solve corner self intersection.

[Tommy804]

Hi, in the back id like to have it just end straight

and in the front id like to get it to bend smoothly around the curve

[eleven]

Hi, it looks like you’re trying to model an inflatable boat. Try offsetting your rail - the blue line on the exterior of your ‘tube’ - to the inside, this willgive a better result.

[jeremy5 (Jeremy)]

Hi @Tommy804,

I would make a new rail along the centreline of your tube and create a new swept surface. Only do one side - you can mirror it to get the second and apart from being quicker, the surfaces will match.

1. To get the centreline create circles from isocurves at intervals. Then put a point at the centre of each:
   

   

2. Draw a curve through the points to create a centreline for the long side. Draw a second for the half front section. Rebuild the long curve and then adjust the control points to improve the match to the tube centre by eye. The side and front centrelines should meet and be joined:
   

   

3. Use Circle around Curve to create a circle of the correct radius for the tube at each end of the centreline. Then use Sweep 1 with the centreline as the rail and the two circles as the swept objects. Tick the Untrimmed Mitres option in the sweep dialogue:
   

   

4. Create a curve from the isocurve around the mitre:
   

   

5. Pipe the curve to create a trimming object to remove material from the surface on each side of the mitre, so you can blend the surface and soften the corner:
   

   

6. Use the ring to split the surface and delete the unwanted part:
   

   

7. Blend the two surfaces, using the Curvature option, and join the parts. Then mirror the whole surface to create the other side. Join the two sides. Finish by using Cap planar Holes to close the two ends and create a closed polysurface:
   

   

HTH
Jeremy

[Tommy804]

Thank you, Jeremy for your help. Works great.