Question about best choice of material

[b8factor]

Greetings,

I am new here. I have the desire to make a model of a star ship from a game i play called Homeworld. I have made a model from scratch before when i was young of a sailboat and did it with white oak, came out great but took forever!

I would like to carve the ship and then make a mold and do an epoxy model.

I am not exspereinced with the easiest way to do this so i am asking for advice? I was thinking foam, balsa, or clay? Since the ship has a lot of straight lines i thought balsa might be best? Any advice on difficulty and expense on the many methods?

Billy

[Rocketeer]

If the model has a lot of straight lines you might consider using styrene sheet. It's a lot easier to get a smooth surface using plastic than wood.

Fill seams and build contours using Aves Apoxie Sculp or Milliput White.

[Mark Yungblut]

Here are a couple of articles from the site to give you an idea of techniques for building.

http://www.starshipmodeler.com/tech/promat.htm

http://www.starshipmodeler.com/tech/my_scratch.htm

http://www.starshipmodeler.com/tech/my_scratch.htm

Many more useful articles here:

http://www.starshipmodeler.com/tech/techmain.htm

[Ziz]

My standard scratchbuilding 101 advice - do a mockup. Get some corrugated cardboard boxes and masking tape and whip up a prototype build. This will help you work the bugs out of the system as far as angles, measurements and order of construction. Make your mistakes where it's cheap, fast and easy to correct and the final build will go that much smoother.

[b8factor]

I was actually going to get block of wood or foam and carve the model out. Then once i have it done, mold it and duplicate with epoxy.

as u can see the ship is very basic:
http://img62.imageshack.us/img62/9674/v ... r580x3.jpg

[Rocketeer]

You might look into a material called Renshape, a material intended expressly for model building.

[Tankmodeler]

as u can see the ship is very basic:
http://img62.imageshack.us/img62/9674/v ... r580x3.jpg

Actually, the shape looks to have a lot of complex yet subtle curves. This won't be terribly easy to carve free-hand. That's for sure.

There are also a lot of indented areas and details.

Cool ship, but you've not picked an easy subject to start scratchbuilding starships!

Paul

[Mark Yungblut]

I was actually going to get block of wood or foam and carve the model out. Then once i have it done, mold it and duplicate with epoxy.

as u can see the ship is very basic:
http://img62.imageshack.us/img62/9674/v ... r580x3.jpg

Just remember a couple of things. If you plan to put this in rubber, the material you make it from needs to be sealed and smooth. Rubber will transfer any surface texture as well as seep into any porous material.

I would also seriously consider breaking this ship down to basic shapes. work from the inside out and adding to a core shape. Also be cognizant of under cuts etc when you build it out. You may need to part this out to effectively cast this. That is why a mock up might be in order. Build it from pink or blue foam like Joe Brown does and then pattern off of that in a sturdier sub-straight.

[b8factor]

I looked into blue and pink foam but only found sheets and not blocks? Do you glue them together to make sheet somehow?

[Kylwell]

I looked into blue and pink foam but only found sheets and not blocks? Do you glue them together to make sheet somehow?

Yes, just use a foam safe glue like Liquid Nails.

[b8factor]

Thanks guys! You have all been very helpfull, heading to home depot for supplies!

-B

[Joseph C. Brown]

might be easier to link you my post http://www.starshipmodeler.net/talk/vie ... p?t=101315

I was told you do a lot of foam, i want to make a ship, in that link, and was asking what material? Only foam i found were sheets and was wanting to carve from rectangular block.

Was told could glue but would that not create hard seem for tools when doing detail work?

I've worked with sheets of foam for years, just be careful with applying the glue: stay back from the edges. This avoids the seams. I have personally found that Liquid Nails Small Project glue in a squeeze tube is a great adhesive with most foam.

Considered renshape, though nothing about it, and balsa wood.

Renshape is awesome stuff. Here's a link to their site:
http://www.freemanvideos.com/castingres ... oards.html
And it is also very expensive for it's size. A recent quote I saw was a sheet that is 2" x 16" x 60" and priced at $342.28, plus a $45.00 shipping charge.
That is why I work with blue or pink insulation foam - I can easily afford a 2" x 48" x 96" sheet of foam for $30.00 at Home Depot.

Balsa is also great stuff, you just have to really sand smooth the final exterior of the model, and prime it, and sand that smooth, and then paint. If you find a good balsa supplier, I'd consider that.

I am new to this so i am unsure what material, and what basic tool set i will need.

I was going to do a solid ship, it seems a basic design.

Any help would be aprec.

Tool choices depend on what you are using for your build material. Hot-wire tools work well on foam, poorly on anything else. Power tools are too much (usually) for foam, but great on Renshape or balsa.

Some additional data:

First, go to Chris Doll's site: he clearly illustrates how to scratchbuild a very curvy starship from Farscape:

http://www.rendezvous-design.com/cdoll/Models/Moya.htm

He also covers the process of doing this type of scratchbuild better and more clearly than anyone I've ever seen. Mark's done killer mech builds with sheet styrene, but, Chris's method would be better for this ship. Seriously, go to that link and read it all!

One of my build examples: Farscape One, foam covered with putty:
https://picasaweb.google.com/1067338929 ... ldingNotes

Here is a build that I am currently doing with foam, then covering with epoxy:
https://picasaweb.google.com/1067338929 ... ldsFor2012

And here are the class notes from the scratchbuilding with foam classes that I taught for several years at Wonderfest:
http://www.starshipmodeler.info/wfest2k ... ss2003.doc


This should get you started! Good luck with your build!

[Mottom]

Have you googled: HOMEWORLD PAPER MODELS.

Paper models can make good templates.

[b8factor]

After much help from this forum I have some of my parts and tools now, I went with a mix of foam tools, plastic, and a little cheating by have some of the more intricate parts of the star ship hull printed with a 3d printer.

I have a few more questions and once I get started I will open a new post(if i can find proper section) to start blogging the production of the model. Really more for feedback and help than how to since i am somewhat new at these new methods.

QUESTIONS: PS for you skim readers, just look for the underline.
1) I am having a 3d printer print a replica of a star ship made in 3DS max. I have broken it down into parts to print less than 10 inches and will assemble after for a full hull of 24". Breaking it down will allow me to first print it with the device, second allow molding of the parts to reproduce more ships, and third paint before assembly of some of the inside parts. THE QUESTION is what would be the best resource, type of material, mold technique to reproduce these 7 inch hull components so that I can catch the detail, produce near exact copies, but still be able to etch, sand, and shape after molding?

2) The mounting of the model will be floating in front of an asteroid, aprox the size of a basketball. I am cutting this with foam hot wire. I am going to try to push different size balls into the foam to simulate pock marks. Once I have this piece done what material would be best used to coat foam before painting that would retain the detail?

3) If I decide to make some small pieces with the foam. Is there a material to coat foam that will not dilute the detail but protect it enough to push into clay to make a mold for duplication? Wondering from what I have seen if foam is not the best choice for small detailed parts? Maybe balsa wood? Any suggestions would be helpful.

4) I am probably months away from painting, and have never painted my own models. I am too much a perfectionist and have never really had the time to learn the techniques. With the way I am making this model I plan to be able to make duplicates over and over which may give me the opportunity to try my hand at painting. That being said, I will probably want the original production to be done as pro as possible so any recommendations on pros that hire out for paint work? It may pay to find someone in my area so I can watch and learn and then try to reproduce with a copy. Raleigh, NC.

Thanks much guys! Please link me if there are some other good forums, blogs, you tube hosts that have some of the answers I asked above.

-Billy

[Tankmodeler]

1) I am having a 3d printer print a replica of a star ship made in 3DS max. I have broken it down into parts to print less than 10 inches and will assemble after for a full hull of 24".

Holy crap batman! How much money have you got for this project? Have you gotten quotes on these parts yet? Unless your parts are 10" long but very, very narrow, it smells like you're lookin g at several hundreds of dollars in 3D printing before you do anything else. Also check the specification of the machine you are going to use for the printing as 10" is pretty big for the machines with the finer detail capability. The larger machines produce parts with noticable layers, often .015-.025 thick. Getting them smooth afterwards both takes a lot of time and also removes detail.

THE QUESTION is what would be the best resource, type of material, mold technique to reproduce these 7 inch hull components so that I can catch the detail, produce near exact copies, but still be able to etch, sand, and shape after molding?

RTV Silicon rubber mould making material (I use Smooth-on products) for the mould and polyurethane resin for the castings. Standard resin kit materials.

an asteroid, aprox the size of a basketball.

!!!

Once I have this piece done what material would be best used to coat foam before painting that would retain the detail?

The best way to do this is to get the foam ball approximately the shape you want and then cover it in something like "Sculpamold" or Aves epoxy putty (which would be the best material but quite expensive in the amounts you'll need for something this size). While the coating is still wet (or uncured) you can sculpt it into whatever shapes & details you like. You don't have to do it all at once, you can do it in sections as you have time. Once it dries (or cures) it will be hard and durable. The sculpamold is porous but can be painted or primed to seal it. Then it can be moulded directly from there.

3) If I decide to make some small pieces with the foam.

Don't. Just don't.

It will distort all to hell and you'll never be able to get the surface smooth enough without coating it. In which case you might as well build the small parts from styrene or Aves.

Dude, while I admire your chudzspah, I can't but think that you're jumping waaay into the deep end on this project for someone who hasn't scratchbuilt anything but a sailboat, out of wood, back when the Earth was young.

24" long!!, basketball-sized base, all built as a master for casting so you can build a number of them for future enjoyment? That's a helluva project for an experienced producer of masters (as I am). For a beginner? Couldn't you start with a smaller fighter first and keep the size of the whole thing down to 4-5" until you see exactly what you're getting in to?

Normally it's walk before you run, but in this case you haven't crawled in years and you're planning to race Usain Bolt.

Give this a big think before you lay out a LOT of money on a project you can't finish.

Not trying to rain on you, but I wouldn't want you to get a year into this project & get burned out.

Paul

[b8factor]

Holy crap batman! How much money have you got for this project? Have you gotten quotes on these parts yet? Unless your parts are 10" long but very, very narrow, it smells like you're lookin g at several hundreds of dollars in 3D printing before you do anything else. Also check the specification of the machine you are going to use for the printing as 10" is pretty big for the machines with the finer detail capability. The larger machines produce parts with noticeable layers, often .015-.025 thick. Getting them smooth afterwards both takes a lot of time and also removes detail.

Oh yeah its pricey, i have already sent over model and am able to get all 10 peieces done for under a grand. Itis a bit of an investment, but when I decided I want something "cool" money never really factors into my mind. It could be why I am still single? nah....

!!!

I have the foam in a large block, I think/thought this should be the easiest part, just wire foam shape out an odd ball, press differant pebbled and rocks into for dents, and coat and paint. I do not doubt that I am navieve about it but i am optomistic. haha

The best way to do this is to get the foam ball approximately the shape you want and then cover it in something like "Sculpamold" or Aves epoxy putty (which would be the best material but quite expensive in the amounts you'll need for something this size). While the coating is still wet (or uncured) you can sculpt it into whatever shapes & details you like. You don't have to do it all at once, you can do it in sections as you have time. Once it dries (or cures) it will be hard and durable. The sculpamold is porous but can be painted or primed to seal it. Then it can be moulded directly from there.

Oh that doesnt sound good, I figured this would be the cheapo part of the model. Thought there might be a liquid of low viscocity that I could paint on that would double as a protector and base to paint on.

Don't. Just don't.

That is what I thought, just needed some reassurance. haha

Dude, while I admire your chudzspah, I can't but think that you're jumping waaay into the deep end on this project for someone who hasn't scratchbuilt anything but a sailboat, out of wood, back when the Earth was young.

24" long!!, basketball-sized base, all built as a master for casting so you can build a number of them for future enjoyment? That's a helluva project for an experienced producer of masters (as I am). For a beginner? Couldn't you start with a smaller fighter first and keep the size of the whole thing down to 4-5" until you see exactly what you're getting in to?

Normally it's walk before you run, but in this case you haven't crawled in years and you're planning to race Usain Bolt.

Give this a big think before you lay out a LOT of money on a project you can't finish.

Not trying to rain on you, but I wouldn't want you to get a year into this project & get burned out.

Not raining at all Paul, if my 41 years of exsperience at being me, I can say you are dead on accurate! I have started and quit many an exspeienve adventure at large losses. But I have also acheived some pretty amaszing things as well, it is a crap shoot if this will come out or not.

But the die is cast, I am in motion, there is nothing going to stop me... from trying. haha

I know it may not come out the way I see it in my mind's eye, but I am hopefull and to be honest, the 3d printed peieces are practically the entire ship, LOL. The rest is just glue, etch... (mess up, refab, try again), etch, and have someone experienced to paint. And perhaps make another ship and learn to paint myself?

I plan to document the process and post... time will tell if it turn into a mannual of DO NOTS and OUH OHs, or ends up being something really cool! Either way it will be fun trying!


Thanks much for the reply. If you would not mind could I send you a list of the mold supplies I have picked out and see if you have any info/input/suggestions on them?

Model pre modded.
http://img339.imageshack.us/img339/9948/mockup2.gif

[Tankmodeler]

Oh yeah its pricey, i have already sent over model and am able to get all 10 peieces done for under a grand.

That's an incredibly cheap price for that much prototyping.
- What layer thickness will the machine produce?
- Are your parts hollow?
- What is the wall thickness?
- Have you allowed for enough internal bracing so that the model doesn't collapse under it's own weight when completed?
- Have you included alignment features so that it all fits together as smoothly as possible? (this is by far the easiest stage to add this, by the way)

It could be why I am still single?

Sure would be in _my_ house!

!!!

I was referring to the size of the base. A basketball! Crikey!

I have the foam in a large block, I think/thought this should be the easiest part, just wire foam shape out an odd ball, press differant pebbled and rocks into for dents, and coat and paint. I do not doubt that I am navieve about it but i am optomistic. haha

This isn't going to give you the sort of surface you're probably looking for. The more pliable Sculpamold or Aves layer will allow you to capture tiny details and sculpt rims to the craters, ejecta streaks, etc. Pushing things into a lump of foam simply won't do it.

Oh that doesnt sound good, I figured this would be the cheapo part of the model.

It cetainly can be cheapo, but it will look "el cheapo" and will make the model look the same way. An inexpensive base would be a cool plank of wood and a brass or acrylic rod. As soon as you want to do something 3D and expressive, then you're looking at at least some money or it will look like complete crap and make everything else look like crap as well.

Thought there might be a liquid of low viscocity that I could paint on that would double as a protector and base to paint on.

Yeah, there are various primers that you could use, but the surface will look like a smoothed block of something with dents in it, not an asteroid.

The rest is just glue, etch... (mess up, refab, try again), etch,

Question. When you say "etch" here what do you mean? Etching is to use a chemical solution to eat away selected areas of a surface.

Thanks much for the reply. If you would not mind could I send you a list of the mold supplies I have picked out and see if you have any info/input/suggestions on them?

Sure. PM me.

Model pre modded.

Another question: What does "pre modded" mean?

Paul

[Joseph C. Brown]

Alternatives to making an asteroid include just buying one...

On Google, search for:

lava rock boulders landscaping

or:

garden lava rock boulders

Many landscape suppliers carry various selections of pumice / lava stones for gardens - ask if they can get the larger stones in the size of the asteroid you want.

Also look in the larger pet shops that have terrarium supplies for pet lizards, and the aquarium supply sections.

[b8factor]

Well I believe I have several things working for me on the price. For one, the model is slender. But more importantly the fellow doing the model also models and I think he is being kind to me?

To answer the size, thickens, etc questions, let me just link their site if that is okay?
http://www.finnovationpd.com/


I am unsure of alignment features I will be sure to ask that. I have broken the model into pieces at seems to better help putting back together but I know it will need to be sanded a bit.
Here is the digital starting to be broken up: http://img585.imageshack.us/img585/468/frontpieces.jpg


Yeah, I have always been cavalier with money. At my core I am an entrepreneur and understand you have to spend money to make money. Sometimes that philosophy carries over into my hobbies where it doesn’t belong, haha. I can go on and on with some entertaining stories on this subject but let me not digress off point.


Yeah basketball base may be large but I figured if the ship is 24”, and if I wanted to have this ship and several smaller vessels flying around it might be nice to have a large backdrop of an asteroid to help create a scene? It would also give me the ability to attach the ships to the asteroid with wires in the viewer’s blind spot to help out with presentation. My first thought was to hang the asteroid from the ceiling, hence foam for weight constraints. Then I thought I may just make a flat base portion of the bottom so I could put on a desk. I am still up in the air on this, the 24” ship is the focal point so I am going to try to direct my attention to it first and sort out the base later.
Example of one would like to duplicate:
http://img255.imageshack.us/img255/1003/astmu.jpg

You do make a good point about the quality of the base and faults in my originally proposed process to form the asteroid. I got my idea from watching a video where these guys used a hot wire cutter to quickly cut out a shield from foam. They then added a black coloring agent to this liquid sealant and painted it on the foam shield. After, they spot sprayed grey paint over the black and the quickly produce final produce was a fake medal shield. I was impressed with the final product and thought I might try to do the same for an asteroid. But I would like for it to look as real as possible so perhaps a bad idea?


For etch I am talking about the detail panels on the ship. Once I mold the pieces, sand, and prepare for assembly, I would like to take a etching tool, or exacto knife, and etch some relief in the panels for detail. This is something my 3d artist wanted to do in the digital model, and the examples he showed me do look stellar, but I fear they will not translate well in either/or both the 3d printing and mold making. I could see them being points of issue for air bubbles when molding. I think it would be easier to etch them on pre painting.
http://img692.imageshack.us/img692/9074/modelte.jpg
http://img824.imageshack.us/img824/2328/texturea.jpg



“Pre modded”, ha, that is what I get for cross forumn lingo use…. Modded is modified. It simply means to modify the original. The 3d artist is taking the model I posted and smoothing out the angles to make it look more realistic. Since the model was orginaly made to be a unit in a video game they rely on the texturing to make it more presentable. This keeps the size, angles, etc down for rendering reasons.

-Billy



____________________________


-----------------------

Moderator edited to remove image(s)

At this time, images in sig lines and inline images in posts are still not allowed. As a courtesy to people who are still connecting to these boards via dial up and other slowness, we ask that you do not put images in your posts. Instead, please just use a link to wherever the image resides on the web, so folks can go look if they want to.

[b8factor]

At this time, images in sig lines and inline images in posts are still not allowed. As a courtesy to people who are still connecting to these boards via dial up and other slowness, we ask that you do not put images in your posts. Instead, please just use a link to wherever the image resides on the web, so folks can go look if they want to.

My bad, i saw the Img button and just started clicking,

[Tankmodeler]

Well I believe I have several things working for me on the price. For one, the model is slender. But more importantly the fellow doing the model also models and I think he is being kind to me?

To answer the size, thickens, etc questions, let me just link their site if that is okay?
http://www.finnovationpd.com/

Well, no, not really. Companies like this offer a range of services and provide a number of levels of detail that are related to cost. If you getting it done by one of the finer detail processes, one of these parts should be several hundred bucks. If it's one of the lower resolution processes, you will be doing a LOT of clean up on every surface of each part. I think you may want to do a little research on what it is you're getting and what the results mean to your project. If you're unsure, ask me & I can help you with it.

I am unsure of alignment features I will be sure to ask that. I have broken the model into pieces at seems to better help putting back together but I know it will need to be sanded a bit.
Here is the digital starting to be broken up: http://img585.imageshack.us/img585/468/frontpieces.jpg

At the moment that image shows the parts to be solid and that's going to cost you a bomb to get prototyped. Once you shell it out to a nominal thickness, that's when you need to add the bulkheads and the pips and tabs that will help you put it together and in the correct alignment. Remember, even if you are willing to take the time to fuss over every joint, adding tabs & slots almost always makes for stronger joints and a more robust model. And don't forget the internal bulkheads to keep the shapes from collapsing or warping.

Example of one would like to duplicate:

Yeah, putting a modelling compound onto the surface and then sculpting it will make for a much more realistic surface.

After, they spot sprayed grey paint over the black and the quickly produce final produce was a fake medal shield. I was impressed with the final product and thought I might try to do the same for an asteroid. But I would like for it to look as real as possible so perhaps a bad idea?

Things that look good on a "prop" shield frequently don't look so good where it's goiong to be looked at up close. Still, try things, different techniques, find out what works best for you. After all it's _you_ you have to please.

For etch I am talking about the detail panels on the ship.

Ah, you mean "scribe" or "engrave".

This is something my 3d artist wanted to do in the digital model, and the examples he showed me do look stellar, but I fear they will not translate well in either/or both the 3d printing and mold making. I could see them being points of issue for air bubbles when molding. I think it would be easier to etch them on pre painting.

No, it is definitely better, far, far better, to scribe lines and add all the fine detail before you make your moulds. If your prototyping process can capture the detail, then get the 3D guy to add absolutely everything possible to the CAD model. Once you are going down the 3D path, get the CAD guy to do as much as possible. This is why it's usually best to get a higher resolution prototype so that the detail work is done by the computer and you are guaranteed to get everything exactly the way you want with perfect alignment, etc.

One thing to realise is that the moulding and casting process will capture absolutely every single detail, no matter how fine, of the master or pattern. You can't have scratches, fingerprints, spray drips, coarse sandpaper scrapes, anything. The rubber and resin will capture everything.

If you have the finest printing method, it will capture details under .005" (5 thou) easily. Each layer can be under .001". This will capture the smallest CAD details perfectly, including panel lines. The final shape will need a layer of Mr. Surface 500 or 2-3 sprayed layers of filling auto primer with sanding with 600 grit in between and you'll end up with a master that's as smooth as a baby's arse. Which is what you need to do the job.

If you have gone with one of the faster and cheaper processes, the layers can be .013" or even up to .025". The steps are massive. You'll need to use a layer or two of spot & glaze putty over everything just to get to the basic shape and you'll have to add all the fine detail yourself and still risk cracking the filler when you scribe or engrave the panel lines and having to redo that area.

If you have chosen one of the lower resolution processes, you will spend a massive amount of time getting this puppy ready for moulding. I'm serious, you'll be at it for weeks. And that's ussally when those of us who do this more regularly pay the higer prototyping cost to allow us to have a much easier time celaning up the 3D parts when we recieve them.

And as for adding the detail prior to painting, the main problem with that is variability. Each model you make will be different because you'll be unable to make every detail of ship 2 the exact same as ship 1. Not only does the human eye really notice pattern shifts, but you'll be doing the same work over and over again on each copy. Again, seriously time inefficient. You might really like building (I know I do), but doing the same thing several times can really suck the joy out of a project.

“Pre modded”, ha, that is what I get for cross forumn lingo use…. Modded is modified. It simply means to modify the original. The 3d artist is taking the model I posted and smoothing out the angles to make it look more realistic. Since the model was orginaly made to be a unit in a video game they rely on the texturing to make it more presentable. This keeps the size, angles, etc down for rendering reasons.

Gotcha. Of course in model building, you, the builder, get to add all that detial as real stuff and not just a wrapped texture images. What you r CAD guy did is excellent and if your prototyping process will reproduce that level of detail, get him to knock himself out doing as much as possible on the CAD model prior to printing.

Paul

[b8factor]

Taking the advice of people with more experience, the first two portions of the nose are hollowed out with 1/8th inch thick walls.

The volume is 1.92 cubic inches.

http://img189.imageshack.us/img189/9908/nose1e.jpg
http://img837.imageshack.us/img837/5789/nose2w.jpg

I guess when you hollow out there is no getting around undercuts? I am looking for examples of braces that should be used to support the walls but also not make it difficult to 3d print the model, if anyone has a good example I would love to see so I can have the 3d artist install.

Another recommendation was to install a device (pips) to connect everything back together. This is another thing I would like to see an example of?

I was thinking of something like this:
http://img829.imageshack.us/img829/4425/pipu.jpg

To make a few locations inside solid and have a protruding cylindrical male/female key to snap pieces together?

I think it designed right they could:
1) Provide areas of strength in key locations
2) Make easier to connect
3) Fill in some more difficult parts for the 3d printer?

But this is an amateur talking I would love to hear form the more experienced.

-Billy

[Tankmodeler]

Taking the advice of people with more experience, the first two portions of the nose are hollowed out with 1/8th inch thick walls.

The volume is 1.92 cubic inches.

_That's_ more like it, although I recommend 3/16 walls as opposed to 1/8.

I guess when you hollow out there is no getting around undercuts?

No. There is no requirement that you get an undercut. I thought you wanted it. I don't know what CAD program you're using, but in engineering CAD programs, you can shell out the interior without the "ledge" that forms the undercut. Get back to your CAD guy. He should be able to make this go away.

I am looking for examples of braces that should be used to support the walls but also not make it difficult to 3d print the model, if anyone has a good example I would love to see so I can have the 3d artist install.

As I said before, there's NOTHING that 3D printer can't print. Imagine the most funky shapes with the tiniest details and convoluted curves and the printer can make it. It simply doesn't care what the shape is. It really doesn't. Nothing makes it harder or easier. It'a all a matter of resolution and machine time.

The machines with the finest resolutions can make nested hollow balls, ball within ball within ball within ball, with only very small holes to let the support media out that, when cleaned up, have all these balls loose inside each other with no way to get them in or out, yet thy are all obviously intact and rolling around. They can make complete working mechanisms, all at once, with gears and ball bearings and shafts and housings all at once. Not as a bunch of parts that you put together, but all at once from the same print job. And the mechanism works kinematically like the final mechanism should. Look on Youtube or the company web sites for examples of what sort of magic these guys can produce. What we do here is child's play for them.

What will determine the best bulkheads is an understanding of how you will mould the parts. If you are making 1 piece moulds, it really doesn't matter as the bulkkeads won't exist in the final cast parts and they are just to stiffen up the printed parts until the mould it made. If you are going to use 2-piece moulds and reduce the volume of the casting, then the bulkheads should be such that the two pieces of the mould can be pulled apart cleanly. Only you know that direction that will be. If you don't know that now, get with a resin caster and talk it over _before_ you add the bulheads to the CAD file. This is part of the production planning process.

The key to all of this is PLAN FIRST! Build second. I'm beginning to think this isn't how you normally approach a project...

I was thinking of something like this:
http://img829.imageshack.us/img829/4425/pipu.jpg

That's fine, but it doesn't need to be anywhere near that big or on a shelf that produces an undercut. Look at a model plane kit and imagine small pips or tabs, say, twice the size as in a good 1/48 plane kit. That would be good enough.

The inside core of a moulded part should come out as smoothly as possible with NO undercuts. Always leave the undercuts for the detail on the outside of the part. If shelling out the part leaves undercuts, fill those areas so that they aren't present on the mould.

To make a few locations inside solid and have a protruding cylindrical male/female key to snap pieces together?

Exactly, but they don't have to be very big at all to be effective. Raised lips on one part with a sunken shelf on the other are also effective alignment features that provide additional surfaces for adhesives during assembly.

3) Fill in some more difficult parts for the 3d printer?

Stop saying this!!!

There's nothing difficult for the printer to make. Nothing. Sheesh!

Paul

[b8factor]

What will determine the best bulkheads is an understanding of how you will mould the parts.

Molding in two parts so the model will be hollow.

The key to all of this is PLAN FIRST! Build second. I'm beginning to think this isn't how you normally approach a project...

Well... Sort of, Actually I thought all this was planning? But yeah I am a jump in and learn the hard way kind of guy, would make a bad engineer! I have a theory that working with software helps enable bad habits. Yes it pays to play there too, but since it is digital it is so far more forgiving.

The inside core of a moulded part should come out as smoothly as possible with NO undercuts. Always leave the undercuts for the detail on the outside of the part. If shelling out the part leaves undercuts, fill those areas so that they aren't present on the mould.

Stop saying this!!!

okay, I think it made it past my eye balls that time,

There's nothing difficult for the printer to make. Nothing. Sheesh!

I think what I meant to keep saying was more expensive to print. I am taking your advice and and putting more effort/expense/etc into the 3d printing aspect of this project. I have a meeting with the 3d printer tomorrow and plan to ask about the images I posted above and the resolution. If there are any other vital questions i should present let me know?

Thanks again Paul, your really helping me out a lot!

[b8factor]

Took out undercuts on inside, added key to place model together.

http://img29.imageshack.us/img29/2621/nose021.jpg
http://img213.imageshack.us/img213/3397/nose022.jpg
http://img100.imageshack.us/img100/5824/nose023.jpg
http://img844.imageshack.us/img844/388/nose024.jpg
http://img826.imageshack.us/img826/4049/nose025.jpg
http://img525.imageshack.us/img525/7414 ... ection.jpg
3.08 cubic inches.


Added some outside attachments that originally was going to be done after 3d printing but decided to do for it.

http://img585.imageshack.us/img585/6928/goblins.jpg



Got word back from the 3d printer, .010 resolution. Not sure that is going to allow panel work via the printer?

-Billy

[Tankmodeler]

Took out undercuts on inside, added key to place model together.

Looks fine

Added some outside attachments that originally was going to be done after 3d printing but decided to do for it.

They should all come out OK, but it might be a good idea to print just the nose to get and idea of exactly what it will all look like, then clean it up and assess whether you can add more detail or need to scale back. It wil probably just cost yo uthe extra shipping charge and a slight bit extra for just the one piece. Well worth the investment to assess exactly what's going on.

By the way, where did the term goblins come from???

Got word back from the 3d printer, .010 resolution. Not sure that is going to allow panel work via the printer?

-Billy

I suspect panels are out, but if you're going to do a test piece, throw everything at it and you'll see what works and what doesn't.

[b8factor]

Top portion of the star ships nose.

http://img337.imageshack.us/img337/1973 ... loadka.jpg

http://img853.imageshack.us/img853/2304 ... load1m.jpg

http://img825.imageshack.us/img825/9679 ... load2t.jpg

I think .01 might not do this justice compared to .006? But i will have to submit the .stl to 3 different 3d printers and weigh the budget versus quality and see.

I did decide to drop the scale down to 15" over 24". that should help some. I am still expecting some massive sticker shock!

-B

[Tankmodeler]

I think .01 might not do this justice compared to .006? But i will have to submit the .stl to 3 different 3d printers and weigh the budget versus quality and see.

what is the difference in height between each of the parallel surfaces in teh panels? If it's .010 or less, then the .010" layer resolution will mean that you'll lose the layer effect generally. If it's .030 or more between the surfaces, you'll be OK, but cleaning up all the nooks & crannies _will_ drive you insane. Take my word.

I did decide to drop the scale down to 15" over 24". that should help some. I am still expecting some massive sticker shock!

It will help at every step of the process, don't forget. The master, teh rubber, the resin, all a lot cheaper. And by the cube of the dimensional difference, as well. Nominally, a change to 15 from 24 inches shuld make the 15" model costs somewhere near 25-30% of the 24" model costs. Not 25% less, but 75% less.

Of course, you will remember, you were warned.

BTW, the ship looks bloody amazing. Good ojb by the CAD guy, for sure.

Paul

[b8factor]

Working on the base of my model display, a large asteroid with a small base to be inserted.

I am using this actual asteroid photo as a guide.
http://i.space.com/images/i/5606/i02/as ... 1292271175

http://www.flickr.com/photos/ehartwell/ ... /lightbox/


This is the concept art of the actual in game asteroid:
http://images1.wikia.nocookie.net/__cb2 ... 0403-j.jpg

And here is my first pass and carving and sanding:
http://www.youtube.com/watch?v=hA-IMkZItnI

Items I used:
Hot Wire Foam Factory Crafter kit.
120 and 220 grit sand paper sponge.

What I think:
It still does not look natural. There are several lines and small patches that I have not been able to smooth out. The asteroid is still about 20% too big so I have some working space to salvage.

What I learned:
1. make the rock shape first, do not try too much detail on first cutting pass. This makes sanding foam very difficult. At least with the tools I am using. If someone knows a better way I am all ears!
2. Add larger craters slowly and work on each one carefully. Do not rush.
3. Add the small details like small craters, some pot mocks, etc last after surface is sanded where you want.

Materials I am going to experiment with for the coating:

Preface:
I have bought and am going to experiment with these materials on small pieces of foam to see which one of I will use for my coat. My goal is to produce an asteroid that looks similar to the real picture above. To make it feel and look professional/authentic* up close. Since this is a very large asteroid it will be more rock like than gritty as planet/moon surface would be. But I also want to keep the weight down to around 10-15 pounds. The surface needs to be sand-able, able to prime and paint.

1. MagicSculpt. So far on a test piece I can tell this still, although very cool, is going to be heavy! I am not very experienced with sculpting but I am having problems getting a smooth surface because the material is sticky and the viscosity is a bit thick.
I am wondering is MagicSmooth might work but I can find no example pictures or photos online.

2. PolyFilla cellulose filler. As seen by this post : http://www.therpf.com/f11/crackers-1-14 ... ndex2.html
I may also try the grout + acrylic polymer mixture.

I think this guys asteroids look great but I want mine to be a bit more rock like since these people decided it was worthy enough to build a star base in.

3. I just ordered some Styroplast and am going to try that as well. I liked that it may hide much of the raw foam detail but the viscosity is low enough to pick up the ridge detail I sand into the foam. It also looks like I can sand, patch, and reapply this material to get it to the smoothness and desired look without a super thick coat. But i have not worked with it yet so we shall see. here is a short video of it: http://www.youtube.com/watch?v=ldKtKtNyxOU


Question I have for the audience:
1. Anybody worked with the items above and can tell me based on what I have stated as my desired end product which you would recommend and why?

2. If I want to install a small styrene base with lights should I coat the exterior first and then cut/machine out the inside or just cut this puppy in half do all the work I need and then glue it back together and sand the seems before coating?

3. Anyone worked with lights know if power source and lights are nested int he foam will I be creating a fire hazard?

4. When trying to create craters and sand I find even the 220 grit sponge tends to rip out foam balls and create line edges. Any technique that would work better to produce smooth round craters in the foam?


-Billy


* professional/authentic I know is very relative to the individual's perspective. The problem I see facing is the ship being printed with a 3d printer will look very nice. I want the asteroid to complement the piece and not look like some hastily put together painted foam prop. Scale is a factor as well when thinking about authentic. This thing is suppose to be the size of small city but in reality is a tad larger than a basket ball. I like the idea of it being rock like but with a well polished smooth surface.

[Tankmodeler]

1. MagicSculpt. So far on a test piece I can tell this still, although very cool, is going to be heavy! I am not very experienced with sculpting but I am having problems getting a smooth surface because the material is sticky and the viscosity is a bit thick.

Good lord, man, how thick are you laying it on???

If you roll it out between two sheets of plastic dusted with baking powder, you can get it really thin, down under 1mm. Drape it over the basic shape, including the larger craters and work it into the surface to get a good bond. To work it in (and smooth it) wet your fingers. The epoxy putty smooths out wonderfully and you can easily blend one sheet into another. Once the surface has a thin coating, you can add more material locally and sculpt it to create the fine detail you are looking for. Don't ignore the possibility of pressing small rocks & pebbles into the putty to produce detail. You can also stipple the uncured surface with a stiff brush to produce a fine texture, like the small pockmarks of the smaller craters.

Notwithstanding the size of your base, I can't see adding much more than a couple pounds of putty if you roll it thin enough and given the generally soft contours of actual asteroids.

2. PolyFilla cellulose filler. As seen by this post : http://www.therpf.com/f11/crackers-1-14 ... ndex2.html
I may also try the grout + acrylic polymer mixture.

While cheap, the grout/polymer mixes are inherantly dense and difficult to put on in thin enough layers. Doing it in patches all around an asteroid shape would be interesting.

Question I have for the audience:
1. Anybody worked with the items above and can tell me based on what I have stated as my desired end product which you would recommend and why?

see above.

2. If I want to install a small styrene base with lights should I coat the exterior first and then cut/machine out the inside or just cut this puppy in half do all the work I need and then glue it back together and sand the seems before coating?

#2, and if you cut it cleanly and glue it back together with minimal glue squeeze out, you probably don't need to "fill" it at all. The overcoat material will fill any seams you might have created.

3. Anyone worked with lights know if power source and lights are nested int he foam will I be creating a fire hazard?

If you are using incandescents of any real size (3-5 watts) then you run the risk of overheating & melting the foam. It's unlikely to burn, but it sure may melt & distort. If you are using LEDs, then you're pretty safe. Make sure anything that may dissipate any real amount of power, like a circuit board perhaps or a transformer, is not located inside the asteroid. Remember, any heat you put into this thing is likely going to stay in ther because it is made of insulation.

4. When trying to create craters and sand I find even the 220 grit sponge tends to rip out foam balls and create line edges. Any technique that would work better to produce smooth round craters in the foam?

If you use an open cell foam and not the closed cell type (the one with the little foam nodules) you won't have this problem. There's little that can be done to prevent the closed cell type from pulling out the little nodules. Of course, if you are adding a layer on top, it may not be too serious if some of the nodules pull out, as long as the basic shape is achieved. The details are all added in the top coat.

Paul