Rhino Mini Tutorials

[Zathros]

Originally Posted by Golden Bear

I apologize for coming in late on this so do not know the starting premise, but...

Why aren't we using "surface from network of curves?"

In the attached image, the back pair shows something like the canopy used earlier in this thread. I made it simply by intersecting three ellipses. For something simple like this, with only the neat edges, I grabbed all three curves and clicked "surface from network of curves" and you can see the result.

The near pair of images shows that I imposed another line, simply a straight one, in order to show that other cross section curves can be used with this command. However, when the shape gets trickier, the command can have problems and thus I only did the half canopy.

I use this command extensively when forming hulls for my ships. I like to get a complete half hull from bow to stern and then break it up on my own later when it comes time to smash the segments flat.


Carl

I have used that command also but find fit problems that accrue. This probably isn't an issue with one or two pieces. I have to admit that I still use Willja's former technique of making sure each surface unfolds. I just don't like to go back and then find a problem which may change other pieces that are connected, since I tend to use the newly created surface edge as a bases for the next connecting surface. It seems that after you creat these contoured shapes, tyou then have to go back and work on "unrolling" them. I have used that command when stuck and then traced over some of the lines using Osnap to make corresponding rails sets that can then be run. Rhino is amazing in that there are so many ways to get to the same end.

Carl, how do create a template from which to cut a paper piece, from the drawing you just posted?

[Alcides]

I trying to using sweeping 2 rails always I can, I agree with Zathros is my best friend.

by the way one question: How do you design a petal shape in Rhino?

[Willja67]

Originally Posted by Golden Bear

Why aren't we using "surface from network of curves?"

Carl

Believe it or not I didn't know about that command. I'm glad we have others who will post in this thread, cause I don't pretend to know everything.

Quickly for your benefit Alcides, to make petal parts split the surface along the isocurves if they converge, then do what you need to to convert the surfaces inot developable surfaces.

Tim Perry aka Wunwinglow taught this method over on the Z-place (before it was the z-place) and maybe he even posted it on his website with all his Rhino tutorials. It would be good to link to that in this thread. I'll look for it or maybe someone who still knows where it is can.

[Zathros]

Wungwinglow give me a lot of tips and support at the other place.. I know he is in this forum. It would be nice if he picked up on this thread.

[Golden Bear]

Use "Smash" for double curved surfaces. You can either Smash holding horizontal square or holding vertical square. Obviously there is some error. This is a place where some art comes in. Depending on the part, I will Smash both ways and then steal the edges and fit them - sort of put the two parts together.

For a surface like that, I would try splitting it different ways and joining the Smashed pieces together at a common edge. It is not a perfect science and requires some practice and skills but it works. For small parts, like ventilator cups - basically half spheres - I can use two Smashed pieces. As the part gets larger and the probability of seams not matching increases, I use more segments.

To match segments, I identify the long edge and then bring two segments together at their mating corners. I'll then rotate one around the joining corner/end so that the close edges line up... with very curvey surfaces, they won't line up too much.

I ALWAYS smash both in U and V directions because there is distortion that occurs along one axis or the other. As with many of the surface tools, there are many funkinesses with smash. You need to play with it and try building the parts as you go, in order to get an idea of how to use it.

Carl

[murphyaa]

I am so gonna watch this thread. One thing I've seen done that would make my life easier is when guys put the panel lines and markings on the model in Rhino. How do you do that? And, after flattening, how do you get it to Save the flattened pieces so I can color them in Photoshop without having to completely redraw the parts.

My methodology now:
1: Design and flatten in Rhino.
2: Screencap
3: Paste to Photoshop
4: Trace over parts
5: Spend a month fixing fit problems, then drawing the panel lines and markings, printing over and over until everything lines up. If I haven't lost interest by then, publish.

What I'd love:
1: Design model in Rhino, including panel lines and markings
2: Flatten and save
3: Open in Photoshop, color, print, test-build and sell.

I've got quite a few models done up as basic Rhino models, just waiting for me to get the courage and time to flatten them and put them on paper.

[Golden Bear]

Sorry to reply to my own post. To do the petal shape, design the piece in 3D - a bulgey cone perhaps made by rotating a curved section line.

Split the surface into radial segments, depending on how many "petals" you want in the end. Again, this may be trial and error to get the correct number of petals to match the size of the part remembering that card has finite thickness.

Then take one of these petals and smash it U and V. Use the one that gets the long edge curves correct and then bring in the curved end edge from the other. You may just want to keep that edge flat anyway. Then copy the lines (or surface if you generated a new one with a new edge, n-times to match the number you chose for your petal.

Once again, almost all multiply curved surfaces take trial and error to lay out using smash.


Carl

[Zathros]

@Goldenbear, that's intriguing, the technique is etched into my mind.

When the term petals is used, is that as in "flower" petals?. A little ignorant here. I did a flower vase in Rhino once and made 4 different flowers. I made the flowers and under "Transform" I used the "Bend" command to make what ever shape I wanted with them. These shapes did unfold and the flowers were build able.

@murphyaa, I made a toy for my son once and to make the panel lines I actually made "parts" superimposed onto the flat piece. The result was when you rendered the parts, since it was straight on "Top View" they looked like a panel lines, Windows, etc. In the Perspective view, it looked like I was rotating a city. Or you could "interpolate the line on the surface", under "Curves".

[Golden Bear]

My enormous apologies for hijacking this thread which I think was going elsewhere. I'll desist after this post.

Z, I believe he is asking about using petals to model an ellipsoidal partial surface.

Here is how I do petals. I've designed a simple rocket nose, shown in 3d in the first image. I then smashed it (u) and (v) wouldn't develop. Then cut the nose in half and smashed it (u) and (v). You can see that (v) has more the shape that will be useful but it is FLAT on the edge that would join to the cylinder.

I also split the nose into three portions and laid them out. You should get the idea that the more sections/petals you use, the better approximation to the bulgey cone shape you will get. However, if it is to be just a little part, a couple mms, you might even get by with just the two petals and counting on being able to distort the card a little as you form.

In the second image I try to show some basic manipulation that could lead to a useable 3 petal part. Just copying the (v) image across and linking at the corners will give a very respectable part. For this I might actually overlap the parts a tiny bit because card is difficult to cut to 1 molecule at the gaps between petals.

On the lower row of the second image, I've taken the (v) layout piece and the curved edge off of the (u) piece. You can see the relative distortions by the lack of fit. So I scaled the edge to match the (v) part and then copied. From here, I might try to rotate the segments a tiny bit so that they don't line up straight. However, from experience, I am pretty certain that the curved line from the (u) piece has too great a radius and would do a scale1d to flatten it, if I used it at all.

My actual first attempt would be to use the image above with the straight edges and then see how I liked the fit in actual card. Frequently it seems better to leave the edge flat and increase the number of petals.

Carl

[Willja67]

Murphyaa, I add the panel lines before I unroll then they come with the part when I unroll it. Then I use dupborder to trace the unrolled part then export using adobeillustrator format(.ai) and import into Corel Draw. Layers are alos your friend. I generally use 5-6 and they will export with the file. I don't know photoshop but I would guess layers are pretty standard. I once posted a little thing on Z-place about how I layered the wing of my Super Corsair. I'll have to recreate it but if you are interested I will.