Struggling to create solid

I’ve been trying to create a solid all day by joining a cylinder a cone and a curve network together. About 3 goes out of 12 have been successful, but it’s not reliable enough to make the whole model. I don’t know whether it’s my tolerances that are out, or if trying to join a curve network to a cone is asking for trouble or even whether there’s a bug in Rhino Mac.

I’ve attached four models to show the steps.

Step 1 - move a cylinder a short distance away from a cone, connect it to the cone with a quarter ellipse

Now move a slightly eccentric cylinder to cut into the cone and produce a curve from the intersection

Step 2 - move the eccentric cone away, leaving the intersection curve and add two straight lines connecting the curve to the edge of the cylinder (for some reason I can’t get a third straight line to connect to the obvious place - it just won’t locate a connecting handle at the right point)

Step 3 - select the two straight lines, the quarter ellipse, the intersection curve and the circle at the end of the cylinder to create a curve network. This seems OK

Step 4 - First join the cylinder to the curve network by doing Edit, Explode then Edit, Join

Then try to create a solid by selecting the joined object and the cone and doing Solid, Create Solid

The message looks ok, but what actually happens is that the cylinder and the curve network get dropped.

Systems details are below and I’ll attach the models (if I can work out how to - UPDATE Problem_Step2.3dm (51.7 KB)think I’ve managed to upload them)

Details from about box are

Software informationProblem_Step1.3dm (60.1 KB)

Software versions
Rhinoceros version: 5.1 (5B161)
IronPython version: 5.1.2015.131
Language: en (MacOS default)
OS X version: Version 10.9.5 (Build 13F1134)


Third party kernel extensions
com.deterministicnetworks.driver.dniregistry (1.0.7)
com.deterministicnetworks.driver.dne (1.0.18)
com.citrix.driver.net6im (1.1.9)
com.Cycling74.driver.Soundflower (1.6.6)
com.sophos.nke.swi (9.4.50)
com.sophos.kext.sav (9.4.50)

Hardware information

Computer hardware
Hardware model: MacBookPro8,1
Processor: Intel Core i5-2415M CPU @ 2.30GHz
Memory: 8 GB
Architecture: Intel 64 bit

Video hardware
Graphics: Intel HD Graphics 3000 512 MB
Memory: 512 MB
Screen size: 1920 x 1080
Displays: S22C350 (102dpi 1x)

USB devices
Apple Computer, Inc.: IR Receiver
Apple Inc.: Bluetooth USB Host Controller
Canon: CanoScan
Mitsumi Electric: Apple Optical USB Mouse
Apple Inc.: Apple Keyboard
Wacom Co.,Ltd.: Intuos PS
Apple Inc.: Apple Internal Keyboard / Trackpad
Apple Inc.: FaceTime HD Camera (Built-in)

Bluetooth devices

OpenGL information

OpenGL software
OpenGL version: 2.1 INTEL-8.24.17
Render version: 2.1
Shading language: 1.20
Maximum texture size: 8192 x 8192
Z-buffer depth: 24 bits
Maximum viewport size: 8192 x 8192

Implementation settings
Use texture compression: No

Appearance settings
Antialiasing: 4x
Mip map filtering: None
Anisotropic filtering: NoneProblem_Step3.3dm (67.1 KB)Problem_Step2.3dm (51.7 KB)Problem_Step4.3dm (68.3 KB)

Thanks for this @Stratosfear.

My ideal requirement was for a curve on the top side gradually going round to a sharp 90 degree connection in the bottom half (hence the sightly Heath-Robinson way of going about it). However, I think after a day of failing I’m going to compromise and go with your suggestion, which does a good job. I think there are possibly two construction principles afoot here, what do you think? -

(i) get a solid that’s close to where you want to be then edit it, rather than building complex polysurfaces and trying to create a solid by joining them together
(ii) because of the complexities of tolerance, joining a complex polysurface, such as a curve network, to another polysurface is more likely to work if the second polysurface is simple (e.g. rectangular).

Just use the ability to create a variable radius fillet with FilletEdge - set the fillet radius to 0 at the bottom. You should orient the horizontal cylinder seam either on top or bottom, and add a handle opposite the seam. Set the handle radii as you want, the bottom one to 0 to create a sharp corner. You can create as many handles as you want to control the radius progression.

Ok, You were on the right track. You just need to explode the cylinder so you have a surface edge to blend from. Explode the cone as well and trim out an elliptical hole. I would use adjust closed surface seam on the cone. So that the seam dose not bisect the trim hole. Then run Surface blend and use add shape to add more control over the blend. Once that’s done run the Join command on all three surfaces. Then run the Cap command to make it a solid.

Thanks very much for this @Helvetosaur. I hand’t appreciated there was so much flexibility and it looks like a good solution.

First couple of times I tried it I didn’t have much luck. With a 12 o’clock handle at 0.5 and 3, 6 and 9 o’clock handles at 0 it took some time thinking about it and then issued the error message “Failure in building rails or surfaces.” With just a 12 o’clock handle at 0.5 and a 6 o’clock handle at 0, it took a while again then issued “Failure in joining parts.” and dropped the cone from view.

I wonder if it’s the cone that’s the problem. I’ll keep fiddling, knowing that I have a fallback if needed. Useful to know about the seam. I’d not appreciated until now that there was one!

Thanks for this @Stratosfear. It worked the first time I tried it. I’ll need a bit of practice to get the hang of manipulating the control handles (the bendy line seems to have a mind of its own when you don’t know what the handles are doing) but I’ve got one of the cylinders to meet in the way I wanted.

I think this solution will help solve a lot of future problems for me.