An attempt to model a ship hull in software.....

[Rick Lutowski]

12 hours ago, Egilman said:

Most ship models, and models in general, deal with scale... much smaller than real life objects... A 1" plate in RL will only be .005" in scale in some of the scales we work in so compromises in design have to be factored in... Interiors although desirable in some models, are not in many others... (what the point of internal compartmentalization in a 1/350th scale warship for example or at 1/700 scale?) A 1/24th or 48th scale model would easily benefit from it depending on the model, but for most modern type ship models it doesn't...

 

Also, 3D printing has certain requirements, a model has to be a solid body to be accurately printed on the better 3D printers... It doesn't matter what the object being printed is for... (even if it is compartmentalized the compartment walls have to be what is called watertight solid) No edge gaps at all... And this is the biggest issue with 3D software at the present... As long as it was just FDM printing it really wasn't an issue but with the advent of Resin printing it does become an issue. many of the models on the download sites can't be printed on an SLA printer because of this...

 

Not trying to tell you not to proceed nor that it has no value, quite the contrary, your idea has great value and for modeling is to me the next logical step in creating a good workflow... But it has to be based upon real world material/modeling requirements. Some things are just plain too small to be modeled accurately.... (and computer cad can accurately draw/measure down to the fractional mil)

 

Have given much thought to all of these issues.  Have concluded that CM Creator should use FDM, and have architected the program accordingly.  The primary driver was the strength of FDM materials, which is better suited for producing thin surfaces that form hollow compartments typical of interior structure.  Another driver was that FDM materials can be transparent, allowing the interior to be seen through a fully watertight hull.  SLA can be useful for some things, such as printing fine structures such as railing, but I envision CM Creator using FDM for most purposes.

 

The biggest challenge has been to figure out how to print fully enclosed compartments without having the ceiling material drop to the bottom of the compartment as it is printed.  The usual approach of using water-soluble support material doesn't work in this case since it cannot be washed out of a fully enclosed space.  The adopted solution was to have CM Creator support Assemblies.  Property crafted assemblies can solve the ceiling extrusion problem.  Assemblies serve many other purposes in CM Creator as well.

 

Good observations, and I think I have solutions to them.  Time will tell once development gets to that point.  Meanwhile, I hope a few brave souls are willing to give CM Creator a try, and provide constructive feedback on what has been implemented to date.  Again, it can be downloaded for free from https://github.com/rlutowski/CMCreator  Windows, Mac, and Linux are all supported, and the complete Java source code can also be downloaded.

[Kevin-the-lubber]

Rick, I'd be a little careful there. FDM certainly has it's place and is currently a good approach for quite large or functional models but my guess is that it will be overtaken by resin within another few years, a bit like Blackberry vs Smartphone. Elegoo will be releasing the Jupiter early next year, with a build volume of 277 x 156 x 300 mm. This is creeping closer and closer to a 'standard' FDM build volume and, while the cost is at present relatively high, it will only ever come down. But in any case, I doubt the majority of hobbyists have room for giant models and the challenge we face is reproducing detail at a very small scale. The main problem with resin - fragility - is less of an issue once the parts have a bit of substance and, conversely (in my view), resin is much, much better for thin or very small model parts than FDM, so long as brittleness isn't an issue. And I expect resin manufacturers are beavering away at improving this aspect of resin for consumer level products. Personally, I wouldn't orientate the software to any particular production method unless that was either the point, or I had no choice. For all we know hobby level sintering or suchlike may be just around the corner.

[Egilman]

Well, there are probably some here that will give it a shot, me I'm heavily invested in SLA at this point.. (I completely bypassed FDM printing) so software devoted to FDM printing is probably not going to work for me...

 

But there are some that are invested in FDM and working out their workflow for incredible models already... It's a good idea and probably the best course is to develop it for FDM and when it is up, stable and functional then add in SLA printing to it...

 

Me, I need SLA for it's precision and fine detail capabilities when I get finished learning, I'm going to be building something in the 6' long range at 1/72nd scale... the ability to print fine detail is a must... FDM isn't capable of that fine a level of detail...

 

I hope it works for ya, if I can help in any way be sure to post....

Edited November 12, 2021 by Egilman

[Egilman]

I believe the best FDM resolution is currently 120 microns? (someone correct me if I'm wrong) The standard for SLA is 50 microns... (and I believe 35 microns is right around the corner) So yeah, for larger models it's ok but you still have to deal with surface roughness after the print... My personal belief is that SLA will overtake FDM as the 3D printing standard within the next year and a half. the guys posting to the STL file download sites are already creating models with the option for SLA printing over FDM... 

 

The changeover is already happening....

Edited November 12, 2021 by Egilman

[Kevin-the-lubber]

I've printed with a 0.2mm nozzle to the point where the surface finish is really not that bad, though sanding filament is much less easy than resin; it's more that getting FDM dialled in can be a right pain whereas this is super-simple with resin. 

 

I think all the manufacturers know what the community wants and this will determine the direction of development: affordable, reliable, easy to operate, no fuss, plug and play, no mess, no post print cleaning etc. Oh, and big. We want parts, not a process! Neither FDM nor SLA entirely fit that bill which is why I think, sooner or later, someone will try budget level sintering or whatever else comes closest to that spec (I have no experience of sintering but it looks like the real thing). The same is true with the software side. My ideal would be Tinkercad with bells and whistles. It took me 15 minutes to learn enough to produce my first part in Tinkercad, more like 15 hours in F360. Obviously Tinkercad is quite limited but with a few additions it could remain very useful indeed, not least because WYSIWYG.

[Egilman]

I have a friend that is doing a Shuttle Stack in 1/160th scale mostly scratchbuilding... but some of the finer parts he has been getting thru shapeways using their ultra fine process...

You can clearly see the ridges, the one on the right was SW's first attempt, the one on the left their last and best attempt, they are the right and left propel motors for one end of a crawler truck....

He also has a complete set printed from the same files that were done on a Photon Mono....

The 16 resin motors are in the top of the array, the bottom left is the shapeways ultra fine offering, and the white one is his scratchbuilt prototype....

You can clearly see the difference between the best commercial FDM printing available and the Photon Mono in a hobbyists workroom...

 

There is absolutely no question that SLA printing is the way to go for detail accuracy, and one must remember this is a 1/160th scale model...

 

I'm not sure how sintering would improve on that but willing to keep an open mind, my friend has decided that SLA is the way to go for all his 3D printed pieces....

 

Hard to argue with the proof... Right now SLA is the cutting edge....

 

Edited November 12, 2021 by Egilman

[Kevin-the-lubber]

As I say, no first hand experience of sintering at all, but here's an excerpt from one of my go-to sites, All3DP.com;

 

"... engineering-grade parts with excellent mechanical properties, fine resolution, and incredibly fast, SLS (selective laser sintering) 3D printing is what engineers and industrial designers turn to for functional rapid prototypes and end-use parts..... advancements in technology have made SLS printers more affordable and compact...  there are now a good number of office-friendly benchtop SLS 3D printers on the market.... SLS also offers a high degree of predictability in material and mechanical properties, so it’s popular in aerospace, medical, and regulated industries. There’s also no need for supports in SLS printing, which expands your ability to design and produce very complex geometries.... This technology can create parts that are finely detailed, strong, durable, heat resistant, and flexible (when needed) all at once. Printer manufacturers often boast that SLS prints rival injection molding products in terms of strength and precision. When compared to injection molding, 3D printing can create parts that have internal channels, lattice structures, and other features not possible with molding...." 

 

Resolution down to 0.05mm. Sounds good, doesn't it 😃. And we're talking metal, plastic, all sorts of material choices. Now the bad part - that resolution would currently set you back at least $40,000. If you can settle for 0.1mm, £6,000. If a machine was available that did even 0.1mm for less than $1000 I for one would be sorely tempted, if it was less than $500 I'd be first in the queue.

 

I haven't tried Shapeways or any other print service but I probably ought to at some point, just to see what sintering delivers.

[Haze Gray]

If I was restricted to only one type of printer I'd have to chose FDM (but luckily I don't have to make that choice!) .    You can get some pretty astonishing results with FDM nozzles that are sub 0.4mm - I've use 0.3mm before and it's big difference in the amount of detail you can resolve. There's still a lot of development in the FMD space - E3D is developing a nozzle change system that's a lot like swapping an air tool https://e3d-online.com/blogs/news/rapidchangerevo  so going for 0.4mm to 0.3 or smaller could be a very fast change.

 

Don't get me wrong though, if there was an affordable SLA machine that had 1500mm Z and 300x300 build plate I'd have one - but I can't see ever fully ditching FDM for SLA entirely based of the type of models that I print.  Changing materials (PLA to ABS) on a FDM is quick and painless compared to changing to a different resin for SLA. 

 

SLS seems like it would have most of the benefits of both SLA and FDM but oh my - that's getting into really expensive territory.   

[Kevin-the-lubber]

1 hour ago, Haze Gray said:

oh my - that's getting into really expensive territory.

Sure is. Don't get me wrong, I'm hanging on to my FDM but I love my Saturn a lot more and that's the one I'd take with me into the lifeboat if I had to choose. I've had decent results with 0.2mm but 0.1mm was best described as hope over experience. Vermicelli galore!

[Egilman]

3 hours ago, Kevin-the-lubber said:

Now the bad part - that resolution would currently set you back at least $40,000.

I don't thunk I have a bench that could support that weight... {chuckle} But yeah the tech is great as far as what it does... someday my ship will come in...

[Egilman]

2 hours ago, Haze Gray said:

1500mm Z and 300x300 build plate

A CR-10 or a Chiron is as close as your going to get, but that's only 500mm Z... {chuckle, without spending a ton}

 

FDM isn't going away anytime soon just because somtin a little better comes along...... It has it's uses and isn't quite finished tech yet..

 

Laser sintering is like molding without the mold it's the gleam in the hobbyists eye right now, but it wasn't that long ago that SLA was the gleam....

 

Moores law.... probably has a relative in the 3D printing business as well...

Edited November 12, 2021 by Egilman

[Rick Lutowski]

Appreciate the feedback to my post about CM Creator using FDM.  It leads me to ask a couple of questions for those of you who have used one method or another (FDM, SLA, sintering, etc):

 

 

1. Which input formats do the various printer types support?

 

CM Creator will interface with the printer system via a data file, so it is mostly a matter of supporting the proper data file format(s).  A common 3D printer data format should allow you to use whichever printer style (FDM, SLA, etc) you want, or use different styles for different parts of the same ship model (if you can afford it!)

 

Also, CAD tools like CM Creator do not interface with 3D printers directly, but with the printer's pre-processing software (Slic3r, Cura3d, etc).  So the better question is not which printer style, but which pre-processing software do you use?  The pre-processing software will then determine which file formats to support. The plan now is to support OBJ, STL, or both since they are supported by all the pre-processors I have reviewed.  Which printer pre-processing packages do you use, which geometric data input formats do they support, and which input formats do you prefer, and why?

 

2. Are SLA or sintering able to produce fully transparent objects?

 

Transparency is needed for printing models with interior structure and fully watertight hulls; if the hull (at least) is not transparent, the interior cannot be seen.  I envision printing the majority of the model using transparent material so the deepest recesses of the interior can be seen; essentially a "glass ship."  Such models are currently very rare -- I personally have never seen such a model, but maybe some of you have.  With CM Creator, fully compartmented "glass ships" (probably made of transparent plastic using FDM) could become common.  Are there transparent resins under SLA?

 

 

 

 

[Rick Lutowski]

48 minutes ago, Egilman said:

Moores law.... probably has a relative in the 3D printing business as well...

 

This why I haven't bought a 3D printer yet, and probably won't until CM Creator's development reaches the point where I actually need one for testing.  The observations of MSW users on threads like this one can be instrumental in guiding CM Creator's 3D print capability, and which type of printer to get for testing, and printing my own models.

[Kevin-the-lubber]

Rick, I just use STL for everything, don't even know where or why you'd use other formats. For FDM I slice with Cura. For SLA, Chitubox and, latterly, Lychee. All three are free and I haven't seen a case to pay for something else. I've printed translucent objects in FDM but I think transparency requires post-printing polishing to eradicate the layer ridges. For a big model ship that could be a fair bit of work. I've done one test print cycle with transparent resin and wouldn't call the results transparent. I understand you can improve this with polishing or (and I mean to test this) by dipping the part in resin post printing and re-curing. However, the common complaint is that the part takes on a yellow tinge during or after curing. In fact, if you look at this rook test piece that has sat on my windowsill for 3 or 4 months, the bottom, which has the greatest density, has become quite ugly. What you're describing sounds like a perspex/acetate level of transparency which I don't think is possible right now.

 

Haze, for sure FDM is cleaner and it's easy to change reels and nozzles, but by the time you've done that and levelled the bed, my little Mars will have already printed my 2mm or 3mm high object and be ready for the next one :-). The mess of resin is a factor, though much less so if you get a wash'n'cure. Actually, I'm starting to sound like an evangelist for resin when in fact I think it's horses for courses and I've probably got more return on investment out of the FDM than resin printers, in so far that I've made lots of useful / replacement house and garden parts from filament but none whatsoever from resin. I did make a nice chess set though!

 

[Egilman]

Yes the STL, (Stereo Lithography) file is the current standard and it's been around almost as long as the OBJ file... They both do essentially the same thing... all the major slicers can work with either as well as most 3D software can import them, but those are the two most prevalent... (with STL leading the two by 20 lengths)

 

Another thing, one of the advantages of Rhino is it can check for watertightness and it is absolute, it either is or it isn't, the same as checking for holes, (which need to be closed) and normal direction which in a good model they will all be pointing outwards.... This doesn't matter to FDM printing, it does in SLA printing... I would consider adding such an absolute feature to it and the reason is this... an STL file created to the absolute standard of rhino will print on any 3D printer without issue, one that is not, probably will still print on an FDM printer but might not on an SLA printer.... On that basis alone Rhino is a leap above other 3D software's that don't do this... The STL files you get out of Rhino will print on any 3D printer... I have model files that will to prove this beyond any shadow of doubt...

 

Transparency, I have no experience with FDM printing so I will defer to the brothers that have, my experience with transparent resin is this... as the part is being printed, and is wet with resin, it is crystal clear, as it cures it takes a translucent haze and is no longer clear more a frosted appearance... Washed in IPA the frosting becomes even more opaque... Fully cured or left out in the sun for long periods it will take on a distinct yellow tinge...

 

In my opinion there is no point in spending more for clear resin given this situation when basic grey gives essentially the same results, you will have to paint your model anyway... hopefully the engineers working on resins will be able to produce a resin that cures completely clear, but it's not on the horizon yet...

[Rick Lutowski]

32 minutes ago, Egilman said:

In my opinion there is no point in spending more for clear resin given this situation when basic grey gives essentially the same results, you will have to paint your model anyway... hopefully the engineers working on resins will be able to produce a resin that cures completely clear, but it's not on the horizon yet...

 

Sort of buttresses my previous conclusion that an FDM printer would be the way to go for printing transparent 'glass ships' if I had to make a choice today.  Will keep my ear to the railroad track on this technology.  If an effective and affordable clear resin is developed by the time CM Creator is ready for it, then I'll  look seriously at STL as Kevin suggests.

 

Concur that STL is preferable to OBJ as an exchange format as it supports more geometric features. 

Good feedback.  Thanks.

 

I'm starting to realize that CM Creator has a bit different goal than that of many MSW users.  Many (most?) of you are focused on creating as beautiful and detailed a model as possible, whereas the goal of CM Creator is to open up an entirely new set of modeling possibilities based on the fusion of comprehensive interior modeling and 3D printing.  'Comprehensive interior modeling' is the key part of this fusion.  Currently, relatively few ship models feature interior details, and the few that do are typically cutaways, so are missing some part of the ship.  Either that or the ship has a part of the hull that is removable, so is not watertight. 

 

CM Creator aims to change that.  Those who want to model the entire ship, inside and out, will be able to do so -- and very affordably -- with CM Creator.  At first the models may not be especially pretty, but the quality will inevitably get better as 3D printing technology evolves.  Thus, the current quality disparity between FDM and STL doesn't bother me.  While print technology is improving, MSW modelers who choose to do so can explore the new modeling frontier opened by CM Creator either by (1) using the 3D print technology currently available, or (2) using CM Creator to fully model the interior as well as exterior of your target ship and printing paper plans of the decks and bulkheads for fabrication using the old tried and true methods.  Either way, the door to creating models of an entire ship, interior and exterior, is opened.

 

If you, like me, are excited about the possibility of modeling an entire ship rather than just the exterior, then CM Creator is for us.

 

[Kevin-the-lubber]

3 hours ago, Rick Lutowski said:

Sort of buttresses my previous conclusion that an FDM printer would be the way to go for printing transparent 'glass ships'

I'm not so sure about that Rick. This is my paintbrush caddy, printed with magenta transparent filament. As you can see, translucent but a long way from transparent. And I did have visions of a glass-like finished article. See this article https://all3dp.com/4/3d-print-glass-like-parts-fdm-printer/; so, it's possible to improve on this example but sanding is necessary, most likely on both sides if it's a hull as that's highly unlikely to be flat, ruling out having one side flat on the build plate. I believe another method is to laquer the parts post-printing (both filament and resin) but I suspect you probably get something more like old bottle glass unless you're spraying flat surfaces.

 

(And in passing, this is why I'll hang on to my FDM, it's great for useful objects).

 

 

 

 

 

 

[Rick Lutowski]

9 hours ago, Kevin-the-lubber said:

'm not so sure about that Rick. This is my paintbrush caddy, printed with magenta transparent filament. As you can see, translucent but a long way from transparent. And I did have visions of a glass-like finished article. See this article https://all3dp.com/4/3d-print-glass-like-parts-fdm-printer/; so, it's possible to improve on this example but sanding is necessary, most likely on both sides if it's a hull as that's highly unlikely to be flat, ruling out having one side flat on the build plate. I believe another method is to laquer the parts post-printing (both filament and resin) but I suspect you probably get something more like old bottle glass unless you're spraying flat surfaces.

 

I went to the original Fennec Labs article, which was better illustrated, and printed it for future reference.  Good tip.  Thanks, Kevin.

 

A fully-compartmented ship model would involve printing very thin surfaces, ideally only one or two deposition layers thick. This should help with transparency, but raises serious issues with structural strength.  I anticipate my initial foray into 3d printing will be a set of experiments to determine just how thin one can print and not have the object crack when subject to normal handling and any needed sanding. The idea of lacquering the surface occurred to me as well as a means of improving strength, smoothing the surface, and possibly reducing the amount of sanding needed.  However, the lacquer would need to be absolutely transparent.  One possibility is a product called Mod Podge.  It is a water-soluble sealant which is used, among other things, as a jigsaw puzzle saver.  When applied it is milky white, but when dry it is absolutely clear in order to not diminish the colors of the jigsaw puzzle.  It also has enough strength to keep the pieces of the jigsaw puzzle from coming apart.  Am thinking it might be a good candidate for lacquering very thin 3d printed surfaces.  Don't know how well it holds up to water once dry and cured (the container says cure time is 4 weeks) -- another experiment to be performed.

[Kevin-the-lubber]

I may have a look at that (mod podge). Presently I'll be experimenting again with the window panes and, while I have some acetate sheet as a backup I'm keen to see how far I can go with resin printing. Thickness-wise, I'm comfortably printing at 0.2mm thick, but those parts are horribly fragile. Here's another thought, arising from my windows fallback plan - what about the package being geared to producing cutting and forming templates, for acetate parts? 

[Rick Lutowski]

1 hour ago, Kevin-the-lubber said:

Here's another thought, arising from my windows fallback plan - what about the package being geared to producing cutting and forming templates, for acetate parts? 

 

Not sure how to interpret your question.  Does "producing cutting and forming templates" mean 'producing' (verb) 'cutting and forming templates' (noun)?  Or does it mean 'producing, cutting, and forming' (verbs) 'templates' (noun)?  I assume 'the package' refers to CM Creator. 

 

The former interpretation is then asking if CM Creator can 'produce' -- perhaps by printing on paper -- templates for cutting and forming acetate parts like windows for a ship model.  Ans: it doesn't do this now, but the capability could be added.

 

The latter interpretation would be asking if CM Creator can 'produce, cut, and form' -- perhaps using a laser cutting system -- templates for acetate parts, or maybe even cut the acetate parts from a sheet directly. Ans: this would be conceptually similar to interfacing with a 3d printer, except producing a 2d template (or part) would have far fewer technical issues than a 3d part.

 

Or, did you mean something entirely different?

[Kevin-the-lubber]

Rick, I mean that, instead of the package being aimed at printing transparent parts straight from the package, with only a slicer in-between, it's aimed at producing templates and/or formers that can be printed as an intermediate step. The templates could be paper, if print accuracy is achievable, or FDM/resin that you mark around or cut to. This is what I'll do for my windows if all else fails, I'll just print the shapes flat in grey plastic, clamp to a sheet of acetate and mark/cut around them.

 

If a primary goal is transparency, I think the printing medium is neither here nor there because neither FDM nor SLA can currently deliver on that without some degree of post-processing which would be quite challenging in many circumstances. The software could be orientated towards an intent to make the parts themselves from acetate. It could produce the patterns and final part trimming templates, as you'll almost always have to have an oversize pattern if forming acetate. Though this is probably well-covered already by laser-cutting/CAM software? It could perhaps be used to design the formers for bending/moulding acetate parts. It's decades since I worked with perspex but it can be formed with heat and retain  transparency https://plasticsheetsshop.co.uk/diy-centrepiece-an-acrylic-bowl/. A package in which you design the part (a hull for instance), specify the material thickness, which then produces a former using algorithms to offset bend allowance and compensate for spring-back might be novel and useful, though very niche. For all I know, this is already available - handmade lignum vitae formers were used extensively when I worked on the aerospace shop floor 40 years ago and I'd be surprised if they weren't now designed on a computer and CNC milled.

 

Can I ask a slightly devils advocate question though; what would CM Creator do that couldn't be done in existing packages? I ask because I can't see any difference, in the sense of using software, between modelling an interior vs exterior? I have interior features modelled on my Victory stern, albeit more for structural than aesthetic reasons and everything I've described above could, in principle, be done in F360. It's fairly straightforward to either design or split models into sections for printing; the tricky part is printing the parts to marry up perfectly, taking into account shrinkage, printer and material tolerances, the limitations of the medium and so on. This would be even more the case for a see-through model as you'd have no 'ugly side' facility and need near-perfection all the way through. It might be worth getting a couple of printers off ebay (they are becoming like smartphones, cheap as chips once a new model arrives) and playing around a bit, to refine your design intent. There are all sorts of limitations that beg for solutions.

[Rick Lutowski]

7 hours ago, Kevin-the-lubber said:

Rick, I mean that, instead of the package being aimed at printing transparent parts straight from the package, with only a slicer in-between, it's aimed at producing templates and/or formers that can be printed as an intermediate step. The templates could be paper, if print accuracy is achievable, or FDM/resin that you mark around or cut to.

 

I think I see the disconnect.  There is more than one way to build a model, and we are each assuming a different way. 

 

Correct me if I'm wrong, but I think the template approach you are suggesting assumes a 'rib-and-plank' type construction where each part of the model is fabricated individually.  Of course, this produces the most realistic model because that is the way most real ships are  constructed. 

 

However, that is not the only way.

 

Ideally, CM Creator would print the entire fully compartmented model at one time as one big part. This would allow the program's users to create prototypes of

(1) new ships being designed (by naval architects), or

(2) existing ships being maintained (by engineers and shipyard workers), or

(3) past ships being remembered (by modelers)

without the muss and fuss of gluing parts together.  Of course, producing such a model in one fell swoop is not possible, as you all know.  So the next best thing is to reduce the parts count to minimize assembly effort.  This is important because the first two categories of user may never have built a model in their life; only the last category of user is comfortable assembling a model from lots of parts.

 

So the question in my mind became: how can a complex subdivided model be printed with as few parts as possible?

 

Recall in WW II the German navy was forced to disperse U-boat construction because of Allied bombing.  Various sections of the hull were built in different locations, often remote, and then transported to a location on the water for final assembly.  This is somewhat analogous to my current plan for 3D printing with CM Creator. 

 

CM Creator is designed around a construct called Assemblies, which are analogous to the U-boat sections.  Assemblies are combined to produce either the complete ship or some portion -- maybe just the hull, or just a deckhouse, or just the mainmast -- whatever is of interest at the moment.  One assembly, or a few adjacent smaller assemblies, would be 3D printed as a single part [the U-boat sections are built].  The printed composite parts would then be manually glued together [the U-boat sections are assembled].

 

Granted, this is not an ideal solution.  The first two user types may still be irked at having to glue printer-size composite parts together -- but, hey, maybe some MSW folks could offer their services to them (for a fee!)  On the other hand, rib-and-plank model builders may complain that printing large composite parts does too much of the work for them, or doesn't allow the material variations they want, or . . . .   However, I think it is a workable solution. But since it is not yet nailed into code, the plan is subject to modification if someone has a better idea that still meets the needs of all 3 user communities.

 

Which gets us to Kevin's last question --

"what would CM Creator do that couldn't be done in existing packages? I ask because I can't see any difference, in the sense of using software, between modelling an interior vs exterior?"

 

Before starting CM Creator, I did a web review of all the existing ship CAD packages I could find to make sure I wasn't reinventing an existing wheel.  I knew what I wanted to do: digitally model the complete interior of a ship, including big ones like carriers, right down to the smallest peacoat locker.  Also, I didn't want to spend a small fortune on software that could do it, didn't want to be forced to use Windoze to run it, didn't want to spend hundreds of hours to learn how to use it, and didn't want to spend man-years developing the digital model to a level of detail needed to build the real thing in order to print a scale model just a few feet long. 

 

In short, the program needed to be low cost or free; multi-platform, easy to learn, and highly productive.  Especially highly productive, else defining all of the 1000's of compartments on a carrier simply would not be feasible -- at least, not until you were actually building it.   I want defining the full subdivision to be feasible in early-stage design.  And not just for 3d print modeling, but digital modeling for other uses too such as:

 

(a) 3D virtual walkthroughs (anyone care to walk through the Bismarck or Titanic -- without transmuting into a fish?);

(b) analyses that require a detailed level of compartmentation (such as emergency evacuation analysis);

(c) computing areas and volumes of all surfaces and spaces for myriad purposes (such as estimating how much material is needed to build, paint -- or 3d print -- the ship);

(d) assisting in ship concept trade-off studies;

(e) digital preservation of museum ships before they finally rust to scrap (nothing lasts forever, but a digital model might come close).

 

The kicker is, I knew how to write such a program because I wrote one while working as a naval architect for the Navy's concept design branch in the 1970's.  The program proved quite useful for modeling and analyzing the interiors of a wide range of ships, including an aircraft carrier. (We didn't need to take these to the peacoat locker level, but I knew the potential was there.) Since I wrote the program on my own time, not the Navy's, they acknowledged I owned the rights and let me take the source code with me when I left.  So what I was looking for in the web search was any indication that the subdivision modeling approach I gave to the Navy long ago might have made its way into a commercial package, or any indication someone might have created something similar.  Either might have precluded writing CM Creator.

 

Result:  I didn't find it.

 

Sure, there were tools, like autoCAD, that can model detail to the last nut and bolt; but that is construction, not concept modeling.  For early stage design, there were a number of tools, like Rhino and freeCAD, that beautifully model the hullform, and maybe the superstructure envelope, but their interior modeling ability -- to the extent they had any -- appeared limited to major decks and bulkheads needed for calculations like damaged stability.  However, I didn't actually spend time and money trying any of them out.  So if anyone has used an inexpensive, multi-platform, easy to learn CAD program and believes it can create every deck, bulkhead, partition, and compartment of a large ship with a reasonable amount of effort, please let me know.

 

Since I didn't see any indication such a thing existed, I pressed ahead with CM Creator, which is now up to v0.5. 

How much longer before it can 3d print?  As usual, the answer is, "it depends."

 

And what about the 'rib-and-plank' modelers; will CM Creator be able to help them?

 

As mentioned, the 3d print plan is predicated on reducing the number of parts as much as possible, and Assemblies are the mechanism for this.  From a software standpoint, assemblies are simply containers that can hold two types of objects:

(1) surfaces defined by "offsets" (naval architecture term), and

(2) other Assemblies.

Surfaces defined by offsets are used by most every ship CAD program out there to define a hullform.  While precise details vary among CAD programs, suffice to say that virtually any surface that can be built can be modeled with offsets, not just hullforms.  So an Assembly in CM Creator could define anything from an entire hull to just one rib or stringer of the hull.  While the latter is not the intended use, nothing precludes it.  So, in principle, CM Creator's 3d print plan could support 'rib-and-plank' modeling.  However, there are currently no mechanisms in CM Creator to define offsets for shapes like ribs efficiently, although such capabilities could be added.  Thus, modeling ribs and such as separate assemblies is not up to CM Creator's standard for high productively at the moment, i.e., it would be a lot of work.  More work than other CAD tools?  Don't know.  After adding an offset generator for ribs, stringers, and such -- much easier.

 

As for the idea of printing paper templates for ribs and such, I had not even thought about that prior to comments on this thread, but I kind of like the idea.  It would be no big deal to capture the output of a transverse slice at the location of a rib to get the template shape.  The time-consuming part would be formatting those numbers into a print file format like pdf or postscript to draw the shape on a paper printer.  At some point, paper print capability probably should be added anyway, but it just hasn't had the priority.

 

And therein lies the problem -- only one of me and a large, and seemingly ever-growing, 'to do' list.  However, like the Linux operating system, CM Creator is open source and copy-lefted, so the door to volunteer developers is wide open.  If anyone on this thread is a Java developer as well as a modeler, or knows someone who has Java experience and would enjoy the challenge of working on a bleeding-edge CAD program, have them download CM Creator and email me.  My email address is in CM Creator's integral help system on the 'Intro Docs-Volunteering' page.  With some help, stronger support for rib-and-plank builders, and 3d printing in general, could come much sooner.

 

Sorry for such a long post, but Kevin touched on probing questions that deserved good answers.  I hope this supplied them.

 

 

 

 

 

 

 

[Kevin-the-lubber]

Ah, yes, talking at cross purposes. I didn't particularly mean plank and frame but in a sense it's the same thing - I meant part by part, just like a plastic or wood kit, rather than pre-formed whole sections. I came at it from the perspective of, I suspect, the typical modeller - we like glueing things together, while trying to make it look like no glueing was involved 😂. The fun is in the making rather than the finished object.

 

I'm not so sure your intent is readily do-able in either SLA or FDM, not just because of the material transparency issues but also because both techs need overhangs to be supported during printing. Another very easy, no-cost way to test it out is to design a section and ask a commercial printing house like Shapeways to quote for the printing, they'll tell you whether it can be printed transparent and with what tech.

[Rick Lutowski]

9 hours ago, Kevin-the-lubber said:

Ah, yes, talking at cross purposes. I didn't particularly mean plank and frame but in a sense it's the same thing - I meant part by part, just like a plastic or wood kit, rather than pre-formed whole sections. I came at it from the perspective of, I suspect, the typical modeller - we like glueing things together, while trying to make it look like no glueing was involved 😂. The fun is in the making rather than the finished object.

 

I'm not so sure your intent is readily do-able in either SLA or FDM, not just because of the material transparency issues but also because both techs need overhangs to be supported during printing. Another very easy, no-cost way to test it out is to design a section and ask a commercial printing house like Shapeways to quote for the printing, they'll tell you whether it can be printed transparent and with what tech.

 

Agree building 'em is more fun than admiring 'em, but admiring would not necessarily be the end goal for 3d printed compartmented prototypes.  Some could have real utility.

 

For example, imagine printing a properly ballasted transparent compartmented Titanic.  Then slice through the forward starboard bilge area for a length of 4 compartments, place it in water, watch the water flood in, and see where it settles, or if it sinks (all the history books say it should not sink).  If it still floats, then extend the slice one more compartment and see if it sinks the way it really did.  If it does, then you have demonstrated a test tank complement to numerical damaged stability calculations, much as tow tank models are used to complement numerical speed-power calculations.  This becomes possible by the ability of CM Creator to 3d print transparent compartmented models.  As a naval architect, I envision 3d printing of compartmented models opening new possibilities for ship designers.

 

As a former docent/tour guide on the Battleship Texas, I envision 3d printed transparent compartmented models having utility in that domain as well.  Sometimes the finished model is not the end of the journey; it's just a waypoint.

 

I fully expect support material to be needed when printing ship model parts and assemblies using FDM.  That's fine provided it can be washed away and does not compromise transparency. 

 

I'll keep your Shapeways idea in mind.  It won't substitute for personal experimentation, but might help advance the starting point.

 

By the way, your observation that the fun is in the making applies to software as well.  For anyone who likes ships, modeling building and programming, volunteering to help with CM Creator could be triple fun!

 

 

 

 

 

[Egilman]

23 hours ago, Rick Lutowski said:

For example, imagine printing a properly ballasted transparent compartmented Titanic.  Then slice through the forward starboard bilge area for a length of 4 compartments, place it in water, watch the water flood in, and see where it settles, or if it sinks (all the history books say it should not sink).  If it still floats, then extend the slice one more compartment and see if it sinks the way it really did.  If it does, then you have demonstrated a test tank complement to numerical damaged stability calculations, much as tow tank models are used to complement numerical speed-power calculations.  This becomes possible by the ability of CM Creator to 3d print transparent compartmented models.  As a naval architect, I envision 3d printing of compartmented models opening new possibilities for ship designers.

This test was actually done by Nat Geo for one of their documentaries on the titanic.... they actually showed it in the sink tank.... Yes it floats with compartments 1-4 or even 2-5 flooded, add a compartment either way and she's a goner... They wanted to make sure that their computer simulations were correct, not only as to would she sink, and the time it took to sink, but would she break where most simulations say she would.... The strain gauges they put in the model hull say yes she would have.... (witness testimonies go both ways on the question of her breaking apart)

Edited November 16, 2021 by Egilman

[Rick Lutowski]

Just now, Egilman said:

This test was actually done by Nat Geo for one of their documentaries on the titanic.... they actually showed it in the sink tank.... Yes it floats with compartments 1-4 or even 2-5 flooded, add a compartment either way and she's a goner... They wanted to make sure that their computer simulations were correct, not only as to would she sink, and the time it took to sink, but would she break where most simulations say she would.... The strain gauges they put in the model hull say yes she would have.... (witness testimonies go both ways on the question of her breaking apart)

 

Yes, I recall reading about that experiment.  These types of tests are very rare because of the expense of creating the test model.  The ability to 3d print compartmented ship models could reduce the cost and effort involved, after which flooding tests could become more commonplace.  Of course, a prerequisite is a CAD tool that can easily define a compartmented ship to any level of detail required, and then 3d print it.

 

The critical witness was Ballard, who discovered the hull in two widely separated pieces split at the engine room.  This corroborated claims that the stern broke off, which were discounted for many years because some of them were made by children.

[Kevin-the-lubber]

I thought I should mention - at dinner this evening my daughter gave me a tour of her unbelievably expensive teeth braces that mean I have to work for another year 🥵. They are called Invisalign and are made from transparent resin, as the usp is that they are virtually invisible. Maybe worth looking at dental resins.

[Rick Lutowski]

When Egilman opened this thread he said:

The point of this thread is to open up the subject of hull building in common solid modeling 3-D design software... (and to sharpen my skills and hopefully everyone elses)

 

Recently much of the discussion has drifted to 3d printing, largely at my instigation I'm afraid, but the thread topic is larger than that.  So, would anyone object if I were change focus a bit and write a few posts about some of the different ways I've seen ship hulls modeled in software over the years, which seems closer to the original intent of the thread.  I'll then circle back to 3d printing since I still have a number of questions about it besides transparency. Anyone object to a temporary shift in focus?

[Kevin-the-lubber]

Egilmans call, as the OP. Digression never bothers me too much as you often learn something interesting along the way.

[Egilman]

12 hours ago, Kevin-the-lubber said:

I thought I should mention - at dinner this evening my daughter gave me a tour of her unbelievably expensive teeth braces that mean I have to work for another year 🥵. They are called Invisalign and are made from transparent resin, as the usp is that they are virtually invisible. Maybe worth looking at dental resins.

I feel for ya... Dental resins... I have a friend who is a dentist, he is also a modeler.... Clear Dental Resins used for alignment braces come out of the printers or molds frosted just like all clear resins do... then they are ground to smooth them and polished.. When polished they come back crystal clear... What it means is surface smoothness is the answer for clear resins, none of them are smooth when formed and solid, like cast glass, lots of post processing before they look clear....  (probably why Invisalign is so expensive)

 

Someone could do a little experiment with Future or one of the diamond finishes using a clear 3D printed model that's frosted and see what happens? maybe it is as simple as clear coating..... when they are in the printer and wet they are crystal clear...