3D hull model to 2D drawing cut patterns

Hi,
I would like to know how can i transpose the hull frames (surfaces) that form my sheet made hull to a 2D drawing in order to be able to cut the patterns on the metal sheets.
I use Solidworks99.

thanks.

[Steve Hollister]

Do you have the hull defined on the computer already - frames, surfaces, or some other definition? To be able to use a computer program to unwrap a developable-type surface, you need to get the geometry into a program that can do the task. There are two geometry definition methods that can be used to unwrap or develop your surface. One method uses ruling lines that get generated between two curves (like a sheer curve and a chine curve) or applied to a surface entity (NURB surface or some kind of surface). The program will then unwrap and flatten out the ruling lines to get the 2D shape. The ruling line approach assumes that the surface shape is "nearly" developable. Otherwise the surface has too much double curvature in it and the plate develop function will not work correctly.

The other development method can also be applied to surfaces which are have some amount of double curvature (plate expansion). These methods are applied to surface definitions (not curves or ruling lines) and use some sort of mathematical (like finite element analysis) technique to flatten the surface and determine any plate stretch or strain that might me induced.


Your first job is to find a program that has a specific function to unwrap or flatten out your surface or curves. There are programs like ours (ProSurf) that use either the ruling line approach or the finite element type strain approach. Others, like CADKEY FastSurf, Rhino, and others use a ruling line approach and work only for nearly developable surfaces.

One of the problems you have to watch out for in these programs is what do you do if the surface is not developable? How do you change the shape of the surface to make it developable?

For more information, see a paper called "Plate Development and Expansion" that I wrote at www.pilot3d.com/tutorials.htm

Steve Hollister
New Wave Systems

[Roger C.]

In other words... the only way to do this is buying another CAD program to unwrap the hull?
Pilot3D it looks like a good software but also is a little spencive (500$).
Having only Solidworks99 there isn't a way to do the job even if it takes longer?

[Steve Hollister]

I don't know SolidWorks99, so I can't really help there. However, try looking the the manual for words like "unwrap", "flatten", "layout", and "developable". Perhaps SolidWorks has a forum where you can post a message? Or, you could search the web for SolidWorks and unwrap, flatten, layout, or developable surface. Doing a surface layout is really not difficult, but it is the sort of function that CAD programs put into separate, add-on packages. Also, these add-ons tend to be geared towards simple shapes, like ventilation ductwork, rather than for complex, curved surfaces.

By the way, if it helps, the student price of Pilot3D is $195 and the student price of ProSurf 3 is $295. Perhaps still overkill if all you want is that one function.

[Stephen Ditmore]

Roger, your last question is the type I think John Fox <http://members.bellatlantic.net/~fcsdsg/> might have the answer to... he wrote a major Professional Boatbuilder Magazine article on using SolidWorks for yacht design.

Sorry I didn't fully understand your question before. I'm glad to see others did, and are lending their thoughts.

Stephen

[Stephen Ditmore]

You might also want to see if http://www.carlsondesign.com/#Fun_Shareware or any of the free packages at Best Free or Low Cost Marine Design Software? (2001-2005)
might be helpful. I've never actually done this business of "unrolling" a panel, except for cylindrical transoms and copying a windshield from a sistership, but I'm nearing the point where I'll need to on my launch project. I've talked with Sam Devlin about this. Sam advocates building a small physical model and taking the final patterns from the model, and has written an article about this for WoodenBoat. He says he's tried a number of programs and hasn't been entirely satisfied with any of them, but was happiest with the results from AeroHydro's software (developer of MultiSurf). Anyway, since I'm planing to use DuFlex from www.atlcomposites.com, my initial thinking is to give them a computer model composed of developable surfaces and leave the task of plate expansion to them.

[Stephen Ditmore]

I wonder if this Brent Swain fella
(brentswain38@hotmail.com) could help you out? (see Unusual boatbuilding technique for steel yachts 26'-40')

I've been looking for some software that will do this efficiently also.

Rhino will flatten 'developable' surfaces. For undevelopable surfaces, you have to create relief cuts as it won't stretch a surface. Try the demo version of Rhino to see if it works for you.

I imagine Solidworks' sheet metal function would work in a similar fashion. I haven't tried it though.

Originally posted by Roger C.
In other words... the only way to do this is buying another CAD program to unwrap the hull?
Pilot3D it looks like a good software but also is a little spencive (500$).
Having only Solidworks99 there isn't a way to do the job even if it takes longer?

Bonjour Roger, Je suis un designer industriel de Rosemère Qc.

Je m'intéresse au design de bateau et suis assez habile avec Rhino. Je pourrait peut-être aider.

Francois L.

inno3d@sympatico.ca

Would Touch-3D from Lundstrom Design <http://www.algonet.se/~ludesign/indexT.html> be a solution for unfolding?

-quote-
Touch3D is program for 3D modeling and unfolding / unwrapping 3D models into flat 2D patterns. It can for example be used for concept design, industrial design, quick prototyping, mock-ups, scale models, marine design, physical renderings, production preparation, etc. Touch-3D can be used both as a separate stand-alone3D modeling and unfolding program, as well as for unfolding models from other 3D modeling, illustration, and CAD programs.

[Jeff]

One limitation (for me at least) is that Touch-3D is a Macintosh program, so Windows users would need to also purchase an emulator. I haven't tried the demo yet because I'm not keen on having to use an emulator (which also adds $150 to the $395 pricetag).