Ship Ribbing with CAD?

[Sanjith_D]

My neighborhood library recently got this cool laser cutter, and I had the idea of maybe using it to build a frigate model a foot and a half long and with detail akin to a half block, maybe a little more.

 

I'm thinking of making the framing and ribs with Vectorworks and then using basswood to manually plank the hull and do the rest.

 

I've however never done any of this before, so I would like to hear your guy’s experiences with whether something like this Would work. I'd also love any tips for any aspect of this project, especially transcribing the Frigate's plan into CAD.

[Bob Cleek]

I believe there are a few kit manufacturers that have done this and sell kits with laser-cut wood for assembly. (See the "sponsors" list on the right side of the forum home page. E.g., Syren Ship Models and Vanguard Ship Models.) Syren Ship Models has a special "installment purchase" group build project for the frigate HMS Winchelsea (1764) going on at the moment. It's a beautiful model and extremely high quality. See:  HMS Winchelsea (1764) by Chuck Passaro|A plank on Bulkhead scratch ship model project|32 gun English frigate (syrenshipmodelcompany.com)

 

Syren Ship Model Company|Boxwood ship model rigging blocks|Ship Model rigging rope |turned brass cannon| Chuck Passaro

 

There are a number of forum members doing CAD modeling and publishing their progress in CAD "build logs" which you can review to get a sense of what's involved in what you are asking about. I must confess that I am a "board and tee-square" draftsman and my knowledge of the CAD technology is general and theoretical, but not practical. As do some others, I find that the manual drafting techniques which I learned long ago in school continue to serve me well for my purposes. There are many advantages to CAD drafting, particularly in terms of presentation to untrained eyes. The ability to produce a 3D rotating projection of a shape as complex as a ship's hull that is instantly understood by any viewer is an amazing feature, as is the easy replication of various modifications in the design process. For those of us who were taught to "read" draughts and thus acquired the ability to "see in three dimensions" the shapes depicted in traditional orthographic projection the advanced features of CAD are "overkill" for modeling purposes. In fact, if you are contemplating creating a 3D CAD file of a particular historic vessel, you will have to learn to read the original orthographic projections in order to translate them for loading into your database anyway. (And from what I've seen looking over the shoulders of the CAD wonks who are doing that in this forum, translating draughts into CAD can be quite a challenging task that I've decided is beyond my ability to master in the time I have left in this life!  ) 

 

To get as good an idea of what you are considering getting into, I suggest you read and follow "CDR Ret's" fascinating "build log" of his digital recreation of SS Galilee, an 1891 merchant brigantine designed by Matthew Turner beginning at:  

As for laser-cutting wooden parts for a model, I expect Chuck Passaro of Syren Ship Models knows as much about applying that technology to creating parts for ship models as anybody and he has addressed it in his many posts on this forum. I would only say that the specifics of laser-cutting technology are way above my pay grade, but I do know that the primary advantage of laser-cutting is in its ability to repetitively produce large quantities of identically shaped parts. This makes it particularly useful in the manufacturing of multiple ship model kits. On the other hand, if you are scratch-building a "one-off" model, getting out your shaped parts is faster and probably a lot more enjoyable doing it the old-fashioned way than spending hours and hours programming a laser-cutter to then burn the parts according to your data, after which you will have to sand the char off all the edges!  

 

As for basswood, I expect as you research your options based on the data here in this forum, you will conclude that it is not a prudent choice of species for the purpose you intend. While it's frequently used in lower- and middle-quality range model kits, and as a soft wood it is easily worked, it is really only suitable for painted finishes and presents finishing challenges even then. It is not suitable for fine carving work which requires a fine-grained hard wood such as box or apple, nor for planking that will be finished "bright" (showing the wood's natural color.) Given the sort of model you are interested in building, I expect you will conclude upon further analysis that there are other wood species that are more easily worked, stronger, and, if you intend to finish any of it bright, far more attractive than basswood. Think of it this way: basswood is like the wood 2X4 dimensioned construction lumber is made of and what you are contemplating building is a Steinway piano.  (Don't let the cost of expensive finish wood species scare you off. A ship model requires so little of it that building with cheap wood is a foolish economy in the end.) 

 

I'm not trying to scare you off at all. I just want to give you what I hope is some direction for finding out what you will probably need to know to get where you want to go. There is always a tendency for newer modelers to "bite off more than they can chew" and there are some significant learning curves to be conquered before anyone can accomplish the incredible level of workmanship that can be seen from what some of the masters of the craft post in this forum. Very few of us will ever achieve such levels of artistic accomplishment, but we all can certainly try. The trick is not to be too hard on ourselves as we journey towards becoming better and better at it nor to discourage ourselves by unreasonable comparisons with prodigies. The greatest enjoyment in modeling ships is simply in the doing of the thing. 

 

 

 

 

Edited March 27 by Bob Cleek

[wefalck]

I think this has been discussed before, watch out for key phrases, such as 'digitising plans'.

 

In general you can import an image of the body plan into your CAD system and then retrace the frames. Once this is done, you have to complete each frame station with the contours of what you actually want to cut. I gather so are aiming for a so-called POB (plank-on-bulkhead) construction. So you need to draw the respective lines for cutting out.

There is a lot more detail that has to go in than can be described in such a short post. You should look at the various contributions in this section here to get an idea.

 

Once you have the basic hull representation in the CAD system, you have to turn this into the files needed for laser-cutting, i.e. arranging the pieces to be cut to fit the machine, efficiently use the wood etc. This file has to be saved in a format that is readable by the laser-cutting software. I gather there is also information on that in this section of the forum.

 

Not sure that basswood is a good choice, I think plywood would be better.

[Sanjith_D]

thanks for all the feedback. I was considering basswood since I had a bunch laying from other projects, however from heeding to what you guys have said, I may reconsider basswood for something nicer. 

[Gregory]

Not necessarily nicer, but plywood will give you more strength for your framing.  Very little, if any will be visible in the end.

[Gregory]

Another consideration will be the software driving the laser.   If the laser controller will support it, see if you can get the community to use LightBurn.  It is relatively inexpensive and is very powerful.   It supports 2D images that it will trace for cutting, giving you the option of skipping the CAD work if you have a good 2D drawing of your frames or other parts.

[iMustBeCrazy]

On 3/27/2024 at 5:22 AM, Sanjith_D said:

so I would like to hear your guy’s experiences with whether something like this Would work. I'd also love any tips for any aspect of this project, especially transcribing the Frigate's plan into CAD

Well, you can follow my bumbling path through the links in my sig with the Lapwing drawings and build (to date) but I seriously suggest you start with something simpler than a Frigate, say a dinghy, skiff, dory etc. in 1:24 or 1:16

 

Meanwhile look for Frigate drawings you like in the best quality you can find, perhaps the Enterprize class, many nice big drawings:

https://commons.wikimedia.org/w/index.php?search=rmg+enterprize&title=Special:MediaSearch&go=Go&type=image&fileres=>1000

https://commons.wikimedia.org/w/index.php?search=rmg+rose+plan+-chart+-painting&title=Special:MediaSearch&go=Go&type=image&fileres=>1000

 

[CDR_Ret]

IMHO, going directly from existing drawings to code that drives a 2D laser cutter is risky when cutting out frames or bulkheads. I have no experience with the quality of plans from the big national museums and other credible sources, but when I manually compared the body and halfbreadth plans of my 1891 brigantine project, it was an exercise in frustration. Heights and breadths of station and waterline intersections did not agree among the three views. The point I am trying to make is that there is no guarantee that using existing plans (especially if they are old, original drafts) will drive a laser cutter that will result in a smooth, fair, hull surface without a lot of extra work.

 

The above observation was the reason I went to CG drafting in the first place. After nearly a decade of periodic frustration, trying different methods and different copies of plans from the Smithsonian and other museum/library archives, I found that using the DELFTship Free naval architecture software was pretty much ideal for fairing out the hull lines because it had the features needed to visualize the shape of the hull, remove low and high spots, and compare the resulting lines to the original drawings. The bottom line here is that obtaining a set of working plans that will actually be fair and eyepleasing in the real world won't necessarily yield the same set of station lines, waterlines, and buttock lines as in the original set of plans you obtained. It is up to you how far you are willing to deviate from the original drawings. There are a number of MSW members who have posted their projects using DELFTship Free, including my own.

Comparison of the final modeled stations (green) in DELFTship Free compared to the original G.C. Berger drawing stations. Waterlines (blue) were included to ensure the correct vertical scale.

To understand the genesis of these lines, please refer to the Galilee research log in my signature.

(High-resolution plans obtained from the San Francisco Maritime National Historical Park Library; G.C. Berger, Pacific Marine Research Society; Date and provenance unknown.)

 

Once you have what appears to be a valid set of lines to work with, then you can start thinking about what laser setup to use for cutting out your parts. Remember to cut to the outside-most of the front and back curves for each frame or bulkhead.

 

Terry

[CDR_Ret]

I would recommend checking out this thread regarding laser-cut frames, etc. Kiyoo Iizawa was actively involved in this forum a few years ago and did some beautiful work using CG modeling and laser-cut components. He was writing a manual/book to help modelers get into laser-cutting modeling, but after some attempts at collaboration, I think there was an (amicable) divergence of views on how to present the process.

 

Terry

Edited March 28 by CDR_Ret

[Gregory]

While I agree CAD is great for visualizing the entire ship, in the end, the laser is a 2D tool.   Accurately produced 2D drawings are ultimately what you need to drive a laser, and they can be produced as accurately in a  2D environment as in a 3D one.

[Dr PR]

I have to disagree about the accuracy of 2D drawings, and restate what Terry said.

 

You can draw nice 2D frame/station drawings, but you have no way to tell if they will produce a smoothly faired hull surface. Even working from a Table of Offsets will not guarantee frames/stations for a smooth hull. I have done this several times, and when the 2D frame/station drawings are erected in 3D the resulting hull surface is often wavy.

[AnobiumPunctatum]

I disagree with your meaning, @Dr PR . I have reconstructed until know 3 different ships in 2D and for the first one most of the frames build following my 2D drawings. Everything is fitting really well.

I also checked my 2D reconstruction with 3D models with the help of a colleague and there are also no waves.

For construction in 2D it is really important to check the hull with buttock and horizontal lines. If you forget the buttock line it can produce waves.

I am in the moment busy with the frame drawings for the sloop Fly and I am quite sure that the hull will also be smooth. For my CNC I give later a few tens of a millimeter to allow some tolerances during the build. These are the biggest inaccuracies.

 

 

Edited March 28 by AnobiumPunctatum

[Gregory]

If the 2D drawings do not render well, then they are not accurate. 
 

CAD can certainly help to resolve these inaccuracies, but not having the skills to use CAD,  should not keep you from producing accurate drawings for use with a laser.

 

 

Edited March 28 by Gregory

[Chuck]

While most folks here are concentrating on the software I would first find out the capabilities of that Library laser cutter.  You will want to cut wood ….depending on species that can get pretty thick.  
 

My guess is this laser cutter wont be of high enough power to cut anything more than 3/32” thick basswood.  And certainly not ply unless its very thin.  So check the specs before you start.

 

you would certainly need a 60 watt laser at a minimum but that is pushing it.

 

its far better to use 80 to 100 watt laser.  Otherwise it wont cut the thicker stuff at all.  Smaller machines for paper and light crafts are useless for ship model work.

 

 

[wefalck]

Well, it depends what you are doing with them on a ship model ...

 

Actually, I think there are four different topics here:

 

1) how to convert a 2D-paper drawing into a CAD-drawing

2) how to loft such drawings into a self-consistent data-set that produces a fair hull, and

3) how to convert the resulting CAD-drawing into instructions for the laser-cutter that produce the expected results.

4) is the laser-cutter available suitable for the task in hand

 

As Chuck suggested, it may save a lot of time, effort and money to verify point 4 first. If the available laser-cutter is not suitable, it may be simpler to work the traditional way.

 

On the other hand, as the envisaged model is planned to be only a foot and a half long, one may get away with quite thin (ply)wood or even cardstock. The bulkheads are only needed to define the shape of the hull, if the spaces in between are filled with a softer wood, e.g. balsa. The bulkhead do not need to be structural parts. One has to adapt the building technique to the available tools, in this case the laser-cutter.

 

Some people work from sets of copies of original builders' plans, but it may be worthwhile going through steps (1) and (2) in any case, as this allows you to verify the fairing of the hull before one cuts anything. Even going only through step (1) is useful: if it turns out that a bulkhead is wrong, one can easily correct it in the 2D-CAD and print it out again. 

Edited March 28 by wefalck

[Gregory]

On 3/27/2024 at 11:55 PM, Dr PR said:

I have to disagree about the accuracy of 2D drawings, and restate what Terry said.

 

You can draw nice 2D frame/station drawings, but you have no way to tell if they will produce a smoothly faired hull surface. Even working from a Table of Offsets will not guarantee frames/stations for a smooth hull. I have done this several times, and when the 2D frame/station drawings are erected in 3D the resulting hull surface is often wavy.

@Dr PR,

I'm resurrecting this discussion because I have developed a lot more appreciation for your thoughts in this regard, particularly when it comes to model ship building.

I feel like I may have been unjustly argumentative about the usefulness of a 3D work environment for laser cutting.  Was I ever wrong.

 

My 'scratch' build of Rattlesnake based on the MS plans has stalled after 3 iterations of trying to resolve the shortcomings of the plans in a 2d design environment.

I've been spending a lot of time lately learning Fusion360, now officially just " Fusion ", but try Googling " fusion ", and see how much help you get for Fusion360.

 

I have a lot to learn, but I feel I can now manage the workspace well enough, and can easily create the basic shapes needed for bulkhead type parts. 

 

Being able to manipulate a form and see exactly how the parts fit together before you start making sawdust or smoke ( in the case of laser cutting ) , is another world compared to working in 2D.

I'm looking forward to reviving my actual model building

 

I plan to start a discussion soon about some of the things I've learned about Fusion360, and also get some feedback from other users.

 

[Srenner]

Throwing my two cents in here... to allow for the inevitable accuracy issues when lofting from 2d to 3d, laser burn and xy inaccuracy with the plotting table dont you add extra onto the bulkheads to allow sanding down to a smooth hull as per normal fairing during construction? The question is how much more which is pretty much trial and error until you happy with the results? Perhaps 1mm extra all round the "true" surface?

 

Agree a simple design like a dory in bigger scales will allow for more inaccuracy in first attempts and be more forgiving. 

[Gregory]

In my experience so far, 1mm would be a bit much at  the 1:48 scale I am working at present.  

There is some trial and error working with 2D for my laser, but getting the notches for assembly nice and tight is a matter of a pixel or two thickness at 600ppi in my drawings.

The laser software I use, LightBurn, actually has an offset to account for the laser kerf.  Depending on the job it is typically .07 to .09 mm for me.

I'm hoping with 3D, and Fusion360, that the actual fairing I have to do will be a lot less than I have been experiencing with 2D.

Fusion is accurate to 6 decimal places, so I don't expect to run into any problems there.   When I trace a pattern and specify  a  certain distance from A to B,  it will be that size when I render it  for cutting.

 

If I'm not doing a good job of addressing your concerns, it's because I'm still pretty new to 3D.  

When I get to the point where I'm ready to do some cutting, I'll be better prepared to report some results.

Edited September 6 by Gregory