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 Post subject: Re: The CAD-yard
PostPosted: Sun Oct 09, 2011 10:01 pm 
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Michael,

Yes, the dissimilar material and the different behaviors with heat, humidity, etc., and the gluing of those materials together are my main reasons for avoiding them. I have no problems with using different materials for detail work (such as PE for railings and details, or wooden ship's boats, etc.), but for something like this I feel that wood would be less stable than plastic. As Dean said, my initial idea for the 1/200 scale build is to put together the frames as he's shown them, and then fill between them with Aves Apoxie Sculpt just a little proud of the frame edges, and then sand it down smooth. I'm afraid that without a lot of extra work to seal the wood, the Aves would put moisture into a wood structure and cause issues.

It may be a moot point; I'm going to email the company that Dean linked to and ask what they suggest. From dealing with laser etching and cutting companies in the past, I have a suspicion that they might not be able to work well with styrene of .060 thick without it burning or making soft cuts. In that case, wood it will be and we'll go from there.

The stacks and pilot house will be easy enough: either there is telescoping brass tubing that is the correct diameter (hopefully!) or I'll turn them on a lathe as I did with the stack on my Weehawken. I'm thinking with the turret that I want to cut the bottom/floor and the top/roof (hopefully with the grate detail) circles from styrene, and then figure out some way to wrap them in heated sheet styrene to build up a hollow turret.

Yes, there will be a build blog/log of this beastie, whenever it gets off the ground (or is it off the ways?). I'm working now to get some other projects off the bench and a writing deadline behind me so that I can start playing with this as I return to my Carondeletbuild.

-Devin

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 Post subject: Re: The CAD-yard
PostPosted: Sun Oct 09, 2011 10:48 pm 
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Devin,
If you have a lathe, you could turn up the turrets, pilothouse and smokestack out of whatever material you want. Being an ex-machinist, and those parts being fairly simple shapes, that's the route I would go, but this is your build so it's your call, either way I can supply the dimensioned drawings for each, no problem.

Dean


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 Post subject: Re: The CAD-yard
PostPosted: Mon Oct 10, 2011 1:32 am 
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Michael,

You can have serious problems with dissimilar materials if the model is large and it will be subjected to large temperature shifts. Plastics have a MUCH greater thermal coefficient of expansion than metals, and metals expand more than wood.

For short models (60 cm or 2 feet) you don't have to worry, especially if they stay indoors.

Several people have posted problems with acrylic and styrene in 1:72 scale R/C models, especially aircraft carriers that are up to four meters (12 feet) long. Decks are often painted a dark color that absorbs a lot of heat from direct sunlight. A four meter sheet of plastic will lengthen about 5 mm (1/4 inch) with a 20C temperature rise! In one case plastic sides of the hull warped where they were attached to wood frames.

The best way to glue plastics is to use a solvent - typically MEK (methyl-ethyl ketone) with styrene. It welds the plastic into one single piece. Plastic solvents do nothing with wood. Likewise, good wood glues are often water based, and these don't adhere to plastics.

Many people use super glue (cyanoacrilyc) but I have had horrible results with it. It emits fumes that fog plastics at a distance, and it makes an extremely weak bond that breaks easily with shock.

For gluing dissimilar materials I have found epoxies work best. You can get epoxies in different viscosities ranging from very fluid paints to thick putty. Epoxy paints are very useful for coating the interior of planked wooden hulls. The wood absorbs the epoxy and all planks are very firmly bonded together - you won't get cracks years later after the wood dries.

Phil

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 Post subject: Re: The CAD-yard
PostPosted: Mon Oct 10, 2011 6:43 am 
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Wow, I had no idea plastic would expand so dramatically, nor was I aware of the long term issues. I mainly build model airplanes and it is becoming clear to me that aircraft construction techniques don't necessarily apply to scale model boats. For one thing, airplanes don't last long...

I have built a few rc racing sailboats. These were composite hulls, typically kevlar or carbon fiber, sometimes with wooden deck beams, inwales, and keel boxes. For gluing dissimilar materials on these boats a popular choice is thixotropic epoxy. Hobby Poxy used to make this stuff but no longer, so I use plumbers' thixotropic epoxies from the hardware store. It seems to glue anything to anything else. Lead bulbs to carbon fiber fins, kevlar to plywood, aluminum to balsa, kevlar to carbon. Some examples here:

http://www.grovestreet.com/jsp/picview. ... howtrash=1

Never tried it on styrene or other common plastics, though. I agree completely on CA -- noxious, brittle, and allergenic.

Congratulations to Dean and Devin on this excellent project -- the whole forum is caught up in the spirit of it!

Michael


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 Post subject: Re: The CAD-yard
PostPosted: Tue Oct 11, 2011 1:41 pm 
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Dean,

I have intermittent access to a lathe. My father has a full machinist setup back in Indiana, but I only get access to that twice a year.

I've considered the PVC route before to make masters of turrets to cast in resin. I'm not exactly sure how to case a hollow resin turret, though (the tube walls and the floor piece). Since I'll need two for Chickasaw, and I have a couple of waterline 1/200 Canonicus and Passaic hulls ready to sheet and detail, I'd like to find a way to reproduce several of them without having to build them individually.

One other option is I have some access to Renshape, Butterboard and other machining material scraps, so turning from those might be a cool experiment, too.

The biggest questions I have now are to do either 1/192 or 1/200 (the two are close enough for me, really, that I don't think it matters), and whether to do waterline or full hull. What I like to do is 1/96th as full hull and 1/200 as waterline, but I think I might go with full hull on this one, just so I can get a feel for it.

-Devin

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 Post subject: Re: The CAD-yard
PostPosted: Tue Oct 11, 2011 5:56 pm 
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First, I'd like to say thanks to everyone that has commented, made suggestions and shared their knowledge on this thread. That's what I had in mind when I started the CAD-yard, somewhere you could show your stuff, ask questions and get answers to a multitude of topics, so keep it coming and I'd like to see more of your guys work, tips/tricks or whatever.

Michael,
thanks for the kind words, and I look forward to seeing some of your work here too.

Devin,
I have a fairly simple idea for making a resin mold for the turrets, I'll do a quick CAD mock-up of it and post it here in a day or two and see what you think.

For your question on whether to do 1/192 or 1/200 scale, like you said, the difference is minor, so whichever route you want to go just let me know, it's no problem.

Dean


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 Post subject: Re: The CAD-yard
PostPosted: Wed Oct 12, 2011 2:27 pm 
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Devin,
Here's a quick video and pic of that idea for those turret molds I mentioned, now this is really down & dirty basic, but you'll get the idea.
The parts could easily be turned up on a lathe, so you could possibly have your Dad do them for you if you like.
Also, for the cannon openings, holes could be cut through the side of the mold and two simple oblong slides could be added that mate into the center part, then removed along with the other parts after the resin sets to get the part out.

If you wanted to add rivets too, you could make the outer part two pieces that slide together with dowels, and dremel the divots into each half (lots of work if you ask me). Or you could just buy rivet strips.

One more thing, buts it's pretty expensive, is have the turrets 3D printed. (I attached a video on that too)

(I still haven't figured out how to embed youtube vids yet)

Link to mold video: http://youtu.be/Gb4VOr5FMD4?hd=1

Link to 3D printing Vid: http://youtu.be/ZboxMsSz5Aw

Image


Dean


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 Post subject: Re: The CAD-yard
PostPosted: Thu Oct 13, 2011 1:47 pm 
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Dean,

Thanks for the suggestions and the video. I'll have to study that mold tutorial a bit before I can comprehend it; my limited experience with resin casting has been mostly open-faced molds and just a few instances of two-piece setups.

It's funny that you mentioned the 3D printing; ever since I saw a 3D printing company at the 2008 NATS, I always thought that would be a great way to make ship model components. Of course printing a master that way means I still need to cast that master in resin to be cost effective, I like the idea a lot. I have a buddy who's a toy sculptor and he used to have one of the big refrigerator sized printers that used wax, but he got rid of the thing when we couldn't get spare parts for it anymore.

As a matter of fact, I've been thinking of downloading Blender and seeing if I can draw up a turret as a first/learning project. I have Rhino3D, but the copy is years old and I've never used it, so I think something like Blender would be a better bet for me starting out.

-Devin

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 Post subject: Re: The CAD-yard
PostPosted: Thu Oct 13, 2011 3:34 pm 
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Devin,

With 3D printing, you would use the actual printed part(s), no need for a master to make more. All they require to print a part is a CAD model, you don't need an actual part to scan like they show in the video. I've seen them in action and they can replicate pretty much all the details on a part you would want. And depending on what material they use, worst case just a lite sanding is needed and it's ready to paint.

As for Blender, it's more an artistic modeling program, not an actual CAD program. If your just starting out and thinking of doing some drawings then Rhino would be better for that, old version or not (lots of vids on YouTube for help). I'm not dissing Blender (I'm working on learning it myself), it's a great program, but it's more for making great images, animation, and models for games and movies, not so much for drawings. Maybe Owen can elaborate some more on that part.

Dean


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 Post subject: Re: The CAD-yard
PostPosted: Fri Oct 14, 2011 12:54 am 
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I have worked with 3D stereolith printing a bit, and I have friends that have more experience that I have. There are several substantial problems with 3D printing.

1. It is expensive. Lower resolution printing is cheaper, but has very rough surfaces - something like 0.031 inch or 0.75 mm steps. Very high resolution (0.0005 inch or 0.0125 mm) is available but is extremely expensive. If you want to use quantities of the 3D stereolith parts (without casting) you must be prepared to spend many thousands of dollars. A whole 1:96 scale ship could cost as much as a car.

2. All 3D printing techniques produce rough surfaces, either due to a granularity in the materials or just "jaggies" from minimum thickness digital steps. You need to finish the surface by polishing or by treating with chemicals or paints that smooth the surface. Either method reduces accuracy of the finished product.

3. Some 3D products are very fragile with low mechanical strength. Sneeze on them and they disintegrate. You will notice in the video linked to in the earlier post that the guy really didn't tighten the nut very hard with the stereolith wrench. It wouldn't handle much torque.

4. Some 3D products have very little mechanical stability. These parts warp very easily with temperature and humidity changes. This is especially true of thin parts.

5. All techniques have a minimum thickness for producing parts. This can be as great as 0.050" or 1.25 mm. This severely limits the usefulness of this technique for small scale models. Even on larger scales like 1:96 many small details cannot be reproduced accurately. For example, 6" gun barrels will be about 0.025 inch at 1:350. Many processes cannot produce things this thin. A scale 20mm or 40mm gun would look ridiculous with a gun barrel thicker than a battleship's main battery or a shield a scale two feet thick! For smaller scale models it is useful only for basic large blocky structures like turrets, superstructure or smoke pipes with no fine details.

6. Thick blocky things can be printed easily. Lacy things like antennas or long gun barrels need mechanical support during "printing." For this a complex support structure may also have to be printed as a part of the product. All of this extra structure must be cut away after printing is complete. The cost of the extra material and the labor needed to clean up the part can make a part very expensive.

There is a lot of hype about 3D printing, but it still has a long way to go before it is really useful for modeling. I know a fellow who created a 1:32 scale stereolith of a Bofors quad 40mm mount. The results were disappointing. Many of the finer details had to be bloated to grossly oversize and some of the parts immediately warped after they were cleaned up. The resulting model was mostly unuseable. The cost of such a model is more than $2000US. That's a lot to spend for something that will go into the trash!

Just remember - the world is full of snake oil salesmen who will promise you anything to get your money.

Phil

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 Post subject: Re: The CAD-yard
PostPosted: Fri Oct 14, 2011 8:52 am 
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Phil,

3D printing has come a long way since it's be introduced, and the price has come down considerably, although still not what I would call cheap. The early printers were very rough and expensive, and the detail you could have on parts was low, but that has changed.
Here's a few links to show you some of the detail parts that can be done on the new printers, and like I mentioned earlier, depending on the material used, a lite sanding may be needed, but no more than you would have to do on some cast resin parts. And for something like a turret, you would want a little roughness to give the illusion of iron, so that can also work in your favor.

Guillows type airplane printed
http://www.rcgroups.com/forums/showthread.php?t=1455808

Assorted parts including some boat anchors (older thread showing earlier, rougher parts)
http://www.rcgroups.com/forums/showthread.php?t=1088812&highlight=3d+printing

RC flying wing
http://www.rcgroups.com/forums/showthread.php?t=1470157&highlight=3d+printing

Shapeways company website
http://www.shapeways.com/

And a pic of a bus they sell from the shapeways website
Dimensions: 2in wide x 7.9in long x 3.7in height



Dean


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 Post subject: Re: The CAD-yard
PostPosted: Fri Oct 14, 2011 12:52 pm 
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Dean and Phil,

Good rundown on the ins and outs of 3D printing. I agree that the process has come a long way in the past 10 years. The large wax unit my buddy had would print out great detail for his sized work (6" and larger action figures and accessories), but there was some clean-up. At the NATS in 2008 I talked with a guy from a company that had a 1/700 scale German cruiser completely printed in an ABS like medium that, while heavy on some of the armament details, was light years ahead of what we could do on my buddy's old wax machine.

I checked out the link on the boat anchors and -- holy crap, what a great idea!!! -- the elbow vents. Those things are next to impossible to make by hand! I was also intrigued by the example of the prop shaft struts printed out in a metal substrate that was so solid that the guy had trouble tapping the material for bolts.

The main reason I'd want to have a single printed and then cast the rest is that I'd feel more like I was actually doing something! The canon are also a good candidate for this process, and a few of the brass barrel manufacturers I've spoken too say they have problems with printing the Dahlgrens (multi-surface contours), and turning guns in 1/200 on a lathe is a little beyond my capabilities (1/96th is hard enough).

-Devin

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 Post subject: Re: The CAD-yard
PostPosted: Sat Oct 15, 2011 12:02 am 
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Dean,

I'm not trying to be argumentative here, but just point out some facts. All of these examples are large scale. The busses are about 1:50. The anchor is about the same, and the Hellcat appears to be 1:20 or so.

The "fine" details in these examples appear to be 1-2 mm thick. Like I said, this is pretty big for scale model ships. For example, a 20mm gun with a 1mm thick barrel would be about 1:25 scale. That's wouldn't be useful on anything I have seen posted on the Ship Model Forum.

Don't get me wrong. Stereolith can be very useful for creating larger objects with complex thick shapes. Things like anchors, bitts and chocks are ideal for stereolith in the larger scales. The best use that I have seen stereolith used for in ship modeling is producing the basic large shapes with little detail. Then smaller hand made details are added, such as wires for hoses, photoetch parts, etc. Then these assemblies are used as mold masters.

Someone may have made a 1:700 ship with stereolith - the hull and superstructure are large enough. Even the turrets could be produced this way. But the details certainly wouldn't be scale.

Phil

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 Post subject: Re: The CAD-yard
PostPosted: Sat Oct 15, 2011 6:03 pm 
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Phil,

No problem, I don't take it as being argumentative, and to an extent I agree, those examples shown in those threads I posted really don't show the detailing that well. The best pics I've found that actually show what is and isn't possible, detail wise, are from the Shapeways website (which I've attached).
And I couldn't agree more about the real fine details, 3D printing does have it's limits, and in a few years it may be possible to do those also, just not quite yet. :smallsmile:

I don't know if you noticed it, but that one thread had a missile 3D printed, now how cool would it be to have your Talos model printed... just a thought.

Ultra detail and detail material comparison:
Image


Ultra detail material painted:
Image


And a little update on the Palmetto State and the newest WIP, the USS Onondaga.

Image
Image

Dean


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 Post subject: Re: The CAD-yard
PostPosted: Sun Oct 16, 2011 8:17 am 
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Holy crap, you got the Onondoga drawn up all ready? That's amazing!

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 Post subject: Re: The CAD-yard
PostPosted: Mon Oct 17, 2011 9:40 am 
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Fast and Furious! :D

Nice work on that Palmetto State. Some crisp lines there sir!

Good to see the Ononadaga.

Owen


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 Post subject: Re: The CAD-yard
PostPosted: Mon Oct 17, 2011 10:16 am 
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Thank you gentlemen,
like they say, the devil is in the details. :smallsmile:

Oh, here's a cool little photo you guys might enjoy. (that's if you don't have it already)

Image

Dean


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 Post subject: Re: The CAD-yard
PostPosted: Mon Oct 17, 2011 10:39 am 
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Never seen that photo colorized. Kind of cool. I saw the original of this, or at least a very good copy of it, at the Mariner's last month.

Question, since we're talking Onondaga: most reports I've read of her say that she had a locomotive headlight fitted to her bow (one instance is here on the Ironclads and Blockade Runners website). I thought at first that this photo might show it, covered:
http://www.history.navy.mil/photos/imag ... h63173.jpg

but then looking at this photo it looks like that might be an auxiliary sail, or someone's laundry drying:
http://www.history.navy.mil/photos/imag ... 1b0040.jpg

Anyone seen a photo of this headlight?

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 Post subject: Re: The CAD-yard
PostPosted: Mon Oct 17, 2011 10:43 am 
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Roscoe wrote:
the newest WIP, the USS Onondaga.


Wow...that is really sharp.

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"Tomorrow is the most important thing in life. Comes into us at midnight very clean. It's perfect when it arrives and it puts itself in our hands. It hopes we've learned something from yesterday." John Wayne

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 Post subject: Re: The CAD-yard
PostPosted: Mon Oct 17, 2011 11:05 am 
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I've got some clear pics of the Onondaga. I found them while combing the online Brady photos resource for pics of Canonicus class monitors.

They are too big for posting directly, so I'll link them Here and Here. They are pretty high-res so don't be afraid to zoom in a bit.

Owen


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