How to model this in Rhino

I'm a bit of a Rhino newbie, so go easy on me....
I've been thru a bunch of tutorials and stuff, but just can't seem to find a way of modelling stuff like the supertstructure in the attached pics.
Anybody game enough to give me a brief step by step on how you guys do it....?

.... please....

 

Mat C there are many ways of getting the shape of surfaces and most people find the best way for them. I find that if you look at the structure you can see that it is usually made up of separate surface types, flats and curved parts. By breaking it down it makes modelling some things a little easier, 3d to me is like building something, you start with the first structure then add or subtract bits till you get to the finish. I did this model with a mix of adding surfaces, trimming and splitting to get edges to make more surfaces and so building up the whole.

 

Thanks - that's just the sort of thing I'm trying to model. Not for any specific project... just to get the hang of it all.
One thing I've had real trouble with is getting the 'joints' between the surfaces right. I might have 3 or 4 surfaces that share common edges, but when I go to fillet them I don't get nice curved adges - particularly at the corners where more than two surfaces meet.
I've looked at a number of tutorials, but these all show fillets or chamfers on solids... not a bunch of separate surfaces.
Any suggestions?

 

Mat C sometimes the best way to fillet edges is to make the surfaces you are trying to fillet into a temporary solid, as solids fillet better then just surfaces. When you finish filleting all you do then is explode the solid to make it just surfaces again and delete the one’s you don’t want.

 

Oh... you see... I didn't even know you could do that!:idea:
But of course... the obvious question.... how do you do it?:?:

 

Mat c in the edit menu “exploded “ ,solids are like polysurfaces explode just separates them into singles.

 

no, no... sorry... I meant how do make a solid from a bunch of surfaces?

 

Another handy method to create a fair transition/fillet from one surface to another is thus:

1. Make the two surfaces intersect (or touch or whatever), if they dont naturally intersect then simply 'extend' the edge of each of them so that they do intersect.

2. from 'curve from object toolbar' use 'object intersection' to create a curve along the intersect between the two surfaces.

3. use the new curve as a guide rail for a pipe (from 'solids' toolbar) using a diameter that is roughly the size of the fair transition/fillet you want.

4. now use the pipe surface to trim the original two surfaces. Probably the pipe will not go to the edge of the surfaces to be trimmed so you need to extend the pipe, or use the intersect curve tool (between the pipe and the surface to be trimmed) to create a trimming curve on the surface to be trimmed -then 'extend curve on surface' to the edge.

5. so now you should have two surfaces (say, the coaming and cabin top) with a gap between them -ie they have a significant and consistent gap between them. Now magic. From 'surface tools' toolbar use 'blend surface' to create a blended surface between the coaming and cabin top.

That’s a basic process, there will probably be a bit of trial an error to get the right blend or fillet size. Can use the same principle in lots of modelling situations with respect to several surfaces intersecting.

Good luck and enjoy yourself,
Rob

 

in "solids" go to "create solid" and select all the surfaces (note the model must be fully enclosed with surfaces(water tight)

 

Thanks RT - will give that a try

Ah - I see now... I was trying to use the create solid command on the 1st of the three models in your example file, but it wouldn't work... so obviously you had to extrude or whatever the 'open' edges to create a 'watertight' set of surfaces.

Thanks heaps

 

And, invariably, one answer creates at least one more question...

once I've done that and then done the fillets, I wind up with holes in the surface here and there... how come...?

 

filleting a solid will be much faster when the surfaces are regular and straight or prism like (or otherwise easy to make into a solid). Rhino filleting can get a bit unstable when it not a solid, the fillet radius is large (relative to the object), and/or the surfaces you want to fillet have compounded curvature (like a coach-roof).
The method I suggested is like a plan B if you want a radiused fillet, or where I find it most useful - where I want a blend between surfaces, not necessarily a radiused fillet.

 

Hahahaha! sorry not laughing at you - with you. this can be a problem of filletting in rhino. Fix it with duct tape. I'v found that these problems can be sorted and fixed manually, but is it worth it? That is to say, what is the model for, and will the holes cause a problem?

If you need to fill the hole (say, for a volume calculation), then simply patch it somehow (two rail sweep, blend etc etc).

If the hole looks bad in a render, then a patch (as above) should get you most of the way there, then a bit of love in photoshop.

Basically if its a problem then patch it up, otherwise dont worry about it. You could spend hours playing with it so that its fillets properly, or you could move on to better problems...

The support forum at rhino is excellent and there will be lots of discussion about how to fillet:
http://news2.mcneel.com/scripts/dnewsweb.exe?cmd=xover&group=rhino

(dont mean to lead people away from boatdesign -but for rhino help they rock.)

 

Mat C sometime rhino will leave some surfaces out because it not certain what to do in that case, so it leaves some nice surface edge to work with. Just use the “surface from 2, 3 or 4 curves” to fill in the blanks. Here is a file you can import with the missing surfaces I created using just that.

 

Thanks guys - really appreciate it. I'd like to be able to tell you that you've cured all my Rhino woes, but I know I'm in for a long, rocky ride!