The Ship Model Forum

Now that I've mastered Rhino enough to start doing IHP model railroad patterns in 3D and then rapid-prototyping them, I am turning my attention to ships. I am practicing first on a never-was battle ship design which may eventually become a pattern for a 1:700 resin ship kit. Does anyone have suggestions or experience on doing effective deck planking? I'd like to engrave it to get the same effect as scribed styrene, if I were sculpting the pattern in plastic it by hand. Is there no way to do it so that the increased number of surfaces doesn't cause your computer to slow down too much? (Doing thousands of rivet heads on streetcar bodies taught me that!) I have an idea how I'd like to approach it on this drawing, but can anyone share ideas or esperiences?

Thanks in advance,

Mike Bartel
IHP
http://ihphobby.tripod.com

If I were just modelling it for render, I'd use a bump map on a texture. A bump map will only affect the normals so that it looks like it dips down, but it dosen't affect the geometry. It sounds like what you need is a displacement map. It's like a bump map, and functions in the same way as far as setting it up is concerned. But instead of just affecting the normals, it actually creates new geometry when you render. On some software, you can have this as a modifier, so you can turn it off while working so your computer can breath. It can be possible to 'apply' the modifier (depending on your software) so that it permanently applies the bump mapping as real polygons.

There are drawbacks to this in that, like booleans, you would get some very messy and hap-hazzard geometry out of it. I know things can need to be 'just-so' for CAM, so I don't want to think about tracking down a few duff faces in all that!

The other option is to create a 'tiled' section, like a tiled texture, but in 3d, of a section of planks. Then use an 'array' modifier to span it along your deck. You'd probably need to use a boolean modifier to get it to conform to your hull sides, but it would be easier to clean up and sort out than the first approach. Again, you would be able to turn this on and off while working and apply it for real when exporting your CAM file.

Owen

That's funny you posted about deck planking/plating, because I was just working on this myself. Like Owen mentioned, a displacement map will do it, but I'm not sure if Rhino can use displacement maps. I'm not a Rhino user myself, so you would know better than I would, but I'm going with a smaller separate pattern, array that bigger than what you need, then trim it to the deck, but this way definitely won't help with the computer slowing down.

Dean

Hi Guys,

Thanks for the suggestions. My first idea was to extrude the profile of the deck planking to the length of the ship as a separate surface, then use a curve as a 'cookie cutter' from the top plan view to get the deck section, then bend it from the side view to the sheer of the deck, then join it in place. That would create a ton of surfaces with all the engraved sections, but it woulde give me the effect I want. I suppose I could put it on a separate layer. I am doing this on a PC, but it is new and has a ton of memory, so it should work. I tried arraying and booleaning out the deck lines, but I couldn't get it to work properly for some reason. More ideas and suggestions are appreciated.

Mike Bartel

I'm not familiar with Rhino (It's all nurbs isn't it?).

You could do the first idea, of having a plank system, but do it lengthwise, rather than cross ways. That way, you only have to make one 'plank' and then dupe it across the width of the vessel rather than do the row of several planks and then dupe that down the length of the craft. That will save you some geometry (or splines in this case!).

The other idea is to put the plank and the cookie-cutter curve on a separate layer, and then turn that layer off till just before printing. Thats what I'm doing with my Monitor model. I've got stuff on separate layers and just turn off what I'm not working on at the moment.

Idea 3 is to do the deck as a separate unit entirely. I'm not sure what kind of file you would need, but you might be able to get away with just using a 2D graphic file (SVG or EPS?) of a deck pattern and have it laser-scribed onto a flat piece of styrene or wood. The deck is then 'poxied down to the rest of your resin model.

Owen

Mike,

Do you have any pics to show of the decking, might be easier to come up with a solution if we could see what it looks like.

Dean

Mike

I don't use rhino, I use KeyCreator. So, The actual functions names may be different, however with a little snooping, you may find that rhino has similar functions.

First, find out what the allowable tolerances are for the litho. The models I've been doing are made for a litho, has a resolution down to 0.002" for details. However when it comes to a relif feature, or etched scored line, the minimum width and depth turns out to be closer to 0.005" without the etch being filled in or lost.

Once you know that..

There are two methods of planking I use. One is relief planking, where the planked surface has to be flush with the surrounding surfaces, such as they are on subs. The second is the "proud" planking where the planking is laid on top of adeck surface as they are on a battleship.

First, the "relief method:

The goal of this demo is to etch planking onto this fictional chambered deck.



First I do a 2D pattern of the deck planking with surrounding boarder, making sure that all areas to be "reliefed" are closed.



Then I use a "extrude closed profile" to use the outline to make a solid that will pass through the deck in question



Here it is relative to my deck.



Then I trim this solid to the deck leaving the bottom edge conformed to the deck shape



Then I have an "un-stitch" function that allows me to seperate the lower face of the solid as a seperate "sheet body (shown in Purple)



see part two

_________________
Best Regards

Fritz K.

And continuing on...

Heres the stand alone, conformed, sheet body..



Then I have a function called "thicken sheet" I use this to thicken this sheet back into a solid. There is an option to thicken in one direction by a distance or on both directions by a total distance. I use the "both directions" and thicken it to twice my desired etch depth to ensure that the body intersections calculate OK.



And here's the body with the deck blank.



Then I boolean subtract the detail from the deck plank to get the relief.



The steps to create planking detail that is proud is nearly the same except for its sort of a "negative" of the above process. This time starting with just the outline of the planks.



Heres how it looks after doing a group "extrude profile to solid"



To be continued again..

_________________
Best Regards

Fritz K.

OK Final demo post.. I promise..

Heres the plank pattern after trimming the solids to the deck blank, and unstitching the lower faces.



Once again I have thickened the sheets into solids using a 'Both directions" option



And Finally, using Boolean add I attach them onto the deck.



Now, as for the file size issue: The only advice I have for you is to stop just before the boolean step. I don't know about rhino, but we have a "subassembly" function. Certain Items can be exported as a sub assembly, and while still technically part of the file (a phantom bound box will be shown in their place) the assembley are stored separately, and the full detail (thus CPU hogging complexity) won't be loaded into active memory, unless you choose to deliberately view them, or actively edit them. I would suggest doing this with scribes/planks solids. Out of sight, out of CPU, until necessary. Then continue working with other items integral to the hull part (lower superstructures etc.). Wait until just before you intend to export the .stl file before attaching everything together. Then, yes you may have a huge file, but you only have to work with it for that one step. Once completed, save it separately, so If you decide to go back and rework something , you can do so with the original smaller and separate files.

Also, In our system, a huge CPU eater is doing booleans on complex, and compound surfaces such as hulls. In the case of a 1/700 battleship, for example, the transverse chamber would barely show up in the finished product. It may better not to introduce any transverse chamber at all. Any areas where the sheer is near flat, (like those in the big five) leave the deck planar altogether. This way the scribe edges data can be saved as linear (data size wise they get described as two connected points). Once you start doing this to a compound surface, each plank edge gets stored as a spline, which has MANY points..

HTH

Unfortunately if you're dealing with subs, this can REALLY cause a file to blow up like the relief planking, and limber holes on this one, simply beacause on a sub, EVERYTHING is a compound surface . Any edits to the hull part at this stage, and my quadcore 2 starts smoking..

_________________
Best Regards

Fritz K.

Nice tutorial... and really nice Sub too, how about posting some pics in the CAD-Yard thread too, it could use some variety.

-Dean

Nice work Fritz, very clearly presented. In Rhino3D the equivalent of the Un-Stitch command would probably be Extract Surface. The rest looks like it could be done using Rhino's Extrude Surface and Trim commands. The Boolean logic commands seem to be identical -- they may be universal. Michael

Fritz, thanks so much for your demonstration and suggestions. I am still somewhat new to Rhino (about 5 months now),so it will take me some time to digest it! I am sure it only seems intimidating , but only because I am reading about it and not doing it.

Mike Bartel

Mike,

For making casting molds I have heard of people using photoetch to create the mold surface for surface patterns like a wooden deck. Just photoetch the board pattern (remove metal for the boards and leave the grooves as a raised pattern) partially through the sheet to the desired groove depth. If you use a good photoetch shop you should be able to get groove patterns a few thousandths thick and tall. Then fit the photoetch sheet into the mold.

This has several advantages: 1) the very fine metal detail will likely last longer than soft stereolith material; 2) you can produce very fine detail with photoetch for a fairly low cost; and 3) you only need a simple 2D line drawing of the board pattern.

If you used the sintered stainless 3D printing the detail would probably be as durable as photoetch, but I don't know if it can produce the very fine detail needed, and it will be a lot more expensive. Plus, you will need a complex 3D CAD/STL model of the deck.

Phil

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A collision at sea will ruin your entire day. Aristotle

I would suggest you be conservative with deck planking on a 3D model. The sheer amounts of extra lines and shapes will make the model almost unusable and quadruple the file size. I tired creating scale diamond plate on some of my models and it slowed my computer to a crawl and the export function would simply crash. For injection molding, the surface texture is usually applied last. That includes decks and tread plate details. The separate method that DrPR suggests is a common one for resin and was used even before CAD became so popular to make masters. Since RP is still somewhat crude, you have to do a lot of finishing on your models before they are suitable as masters anyway. But the technology improves every year.

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Timothy Dike
Owner & Administrator
ModelWarships.com

Yeah, I've had the same things happen with rivet heads and screening. The RDC body I showed on another thread was designed to have screening added on the roof and on the vents directly onto the 3D part. I did this partly because I knew screening probably wouldn't print very well, but their multiple surfaces also were eating up so much RAM and slowing everything down. The idea of doing the deck in PE and adding it separately is a good option, and might be better for a short-run pattern, but if I ever decide to use any of my CAD for injection moulding (an increasing possibility), I will need to know how to do it effectively and when to add it.

Mike Bartel