Rhino Unfolding

[JT Fox]

While playing with Rhino and trying different ways to model wings and then unfold them I came across this message.

"Unrolling doubly curved surfaces will produce inaccurate results."

I've tried to find a way around this and have come up with 2 options.

1) Install a plug-in to do the unfold, cost $200.

2) Re-design the shape.

The first is not an option and the second is a compromise on the shape of the model which I don't want to do.

Anyone got any other options?

Cheers JTF

[Alcides]

Uh oh ... well in my experience the only way is the 2 option.

The point is the paper can't be bend in 2 directions, you can do a cylinder but not an sphere. So the surface has to be "developable".

if you have a doubled curved surface this is impossible to emulate in paper because you cant bend the paper in 2 directions. You need a simple curved surface.

I do not know the plug-in you mentioned but you should ensure that the result is useful in paper.

Maybe if you put a picture some designers would give you advice how simplify the surface.

Regards
Alcides

[JT Fox]

Thanks for that explanation.

I split my shape into more parts and then created the surface from the new edges.

The general shape is still there but it now unfolds.

Cheers JTF

[JT Fox]

I could use some advise on how to design a nose of an aircraft, see picture.

It looks fine but does not unfold. "Unrolling doubly curved surfaces will produce inaccurate results" message.

Any tips on how to re-design this shape so it will unfold.

Thanks JTF

[Alcides]

Do you refer to the "petals" ? If that is the case Could you post a cross section of the nose? I'm asking because it don't look circular and if I'm going to try to help the origin of the petals is very important. Just the curve.

[Dragos]

you could save it as 3ds file and unfold it with Pepakura Designer

[JT Fox]

Attached is the front view.

Dragos.

Exporting to Pep worked but it was a very untidy unfold even after I player around with the edges. It ended up with 16 parts. Too many for a 1/72 nose, in my view, I would prefer 8.

Cheers JTF

[Paperbeam]

Can't you do rings instead of petals? Works for me...

Terry

[Dragos]

It ended up with 16 parts. Too many for a 1/72 nose, in my view, I would prefer 8.
Cheers JTF

I believe this means that the model is more acurate

[JT Fox]

Can't you do rings instead of petals? Works for me...

Terry

That would be one way.

Don't you have to complete the nose with a cone shape and doesn't that make it pointed?

Cheers JTF

[JT Fox]

I believe this means that the model is more acurate

I also believe it would be more accurate but I afraid my build skills would struggle.

I think I may go down the route of slicing the nose into ring as suggested by PAPERBEAM and then create rectangles to replace the petal parts. After unfolding I can then arrange the rectangles into petal shapes for building. I think that makes sense.

Cheers JTF

[grimpirate]

There is a free Rhino plugin that might help you
labs:advancedflattening · McNeel Wiki (http://wiki.mcneel.com/labs/advancedflattening)

[Zathros]

Since we are talking about paper the only way to get that shape the way you want is to use filler. Rhino will get you close enough where the filler would be minimal. You could also try making a plug out of wood and wetting the paper and "smush" it, letting the soggy plug dry, you will end up with the nose, or make one out of plastic, as described by various members. Getter and Chiatwakom have excellent techniques posted. You can get very small compound curves out of 110 lb. cardstock, but you would need to make small curved bucks to form them. Take your thumb and press some card stock between it and a pencil eraser and you will see what I mean.