Question about best choice of material

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Tankmodeler
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Re: Progress Report

Post by Tankmodeler »

b8factor wrote: 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
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Kylwell
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Post by Kylwell »

Talc works better than baking power. I usually roll it out between cling wrap misted with water. Not enough energy in the cling wrap to cause sticking issues.
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b8factor
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Thanks

Post by b8factor »

Thank you fellows, I will give it another go with the magic sculpt. I have no shortage of test pieces!

I also have 16 feet of 2" thick blue board, I guess I could glue that together and start over on the asteroid? Maybe i will try with the one I have first and use that as a backup plan.

I am curious to the the styroplast, it looks pretty neat.

With the magic sculpt I wonder if I can try it with latex gloves to prevent all the finger prints? Though i suppose that wills and out well enough. The stuff was just too thick to get very smooth. I may have had the mixture off I did notice that it said to mix evenly in amount not weight.... after i did it in weight. ha.
b8factor
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Sanding foam

Post by b8factor »

Oh I will add sanding foam(both styro and blue foam) is a PAIN! I bought a charcoal paint respirator and full goggles to wear while doing it since the dust is so fine! I see I should have gotten a paint coveralls as well! Fix that this weekend.

I was wearing the respirator when cutting the foam as well since I am doing it inside (dang mosquitoes are bad right now in NC) but after putting the hot wire cutter near a window with a box fan at the window sucking out the smoke and fan behind me blowing the smoke to the box fan I have completely eliminated the fumes from building up in the hobby room.
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Kylwell
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Post by Kylwell »

I've found working in my spray booth or sanding into my shop vacc to control the dust.
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b8factor
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update

Post by b8factor »

Now that the 3D artist has caught up with school, the front 3rd of the ship is detailed and ready to dead off to the 3d printer!

http://img21.imageshack.us/img21/686/nose2g.jpg

http://img837.imageshack.us/img837/2236/nose3c.jpg

Well almost, he is adding the pips and braces now, but this week for sure!

Excited to see what they produce.
Tankmodeler
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Post by Tankmodeler »

This looks really cool.

Question: Have you talked to the printer to ascertain whether your parts breakdown (top, middle & bottom) is less expensive to print versus two halves, left & right. For some printing systems the total volume deposited determines the price. For some systems it's related only to height and not volume. The larger parts, when laid o ntheir sides may be cheaper than the smaller parts that might only be taller and not more volumous.

Paul
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b8factor
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Post by b8factor »

I have 3 printer contacts, 1 working to keep entire 15"(these 3 pieces are the front 3rd) ship under 1K but does not have a very high resolution. :(

I am heading your warning I may have this printer do 1 piece just to see what it looks like.

The other two, I am told do fabulous work, can print very high resolution (not sure what that is yet) but I was told to be prepared for sticker shock.

But to answer your question, I am going to ask for an estimate as is, and ways I can decrease the cost. Maybe split entire ship in half, maybe even split these 3 parts all in half for 6 so there is as little height as possible if they are laying on their side. I think this would cut down on support material and possibly cost?

I am going to do everything I can to get these printed as high a resolution as I can and not break my wallet.

I broke the ship up like this so that the undercuts are all controlled for molding purposes. The middle component comes together at the seems of the top and bottom to created an indention that would be an undercut in a mold.

I hope i explained that well enough? It is quite late here right now.

-B
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aAdvice

Post by b8factor »

I could use some advice here if anyone has input.

Here are the final STL files, with pips and braces. the wall thickness is 3/16th".

Since I am a novice at molding I wanted to make sure these would be okay to mold without causing too many problems?

http://img21.imageshack.us/img21/2931/nose051ribs.jpg

http://img854.imageshack.us/img854/7793/nose052ribs.jpg

The center piece is baffles me the most. I am wondering if I should have the center piece split is half vertical and join it together with pips on the braces?

The top and bottom were designed specially to make the mold material be able to release. But i wonder if I should have the supports tapered to assist as well?
Tankmodeler
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Post by Tankmodeler »

Looking at these parts, they don't seem too big. What are they, when assembled, approx. 5" x 4" x 1.5"??

If so, you should split the shape along the vertical plane and not in the three peices you have. Moulding would be easier, the undercuts would not be too great and the smaller number of parts would result in fewer moulds and less moulding costs.

The "fin" shape at the bottom would not be too difficult to take out of the mould when cast, the assembly would be easier and I think your total printing costs would be about the same.

I certainly hope I'm not leading you down the wrong path on some of these conversations. 20 years experience in moulding, patternmaking and professional engineering 3D CAD is hard to pass on in a couple of emails. You're doing really well. One thing that alway happens is as some choces are made, other choices should change. When the model was 24" long, the three piece approach worked well. Buit at 15" long, the parts are smaller and, I think, a 2 piece approach to this part of the hull may now be better.

It's the sort of changes in tooling approach that experience would tell me to change and I would do on the fly, in my head, as the configuration changed. If you split the shape in vertical halves, you might even be able to get the thickness down to 1/8 inch.

If the parts were larger and the bulkheads were proportionately deeper, I'd be worried about adding "draft" to them. But, as they stand, if you're only going to make a few copies. you can live without drafting them. If you make the section in 2 parts instead of three, it's even less of a problem.

HTH

Paul
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b8factor
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Post by b8factor »

Hey Paul, your not leading me down the wrong path, no worries. It is my lack of experience, but I am loving every minute of it. I have learned so much in the last couple months thanks to this forum and all your posts!

Artist is combining the parts and splitting vertical. Also going to drop thickness to 2/16th.

Thanks m8!



Time to start mold and casting some plastic toys for practice, I have all the supplies now just need to build a vacuum degassing system!
b8factor
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Update

Post by b8factor »

Ship has been changed to cut vertically for easier molding.

http://img254.imageshack.us/img254/4750/nose061.jpg
http://img31.imageshack.us/img31/3786/nose062.jpg
http://img402.imageshack.us/img402/6086/nose063.jpg

Total ship length is 15". This nose section is the smallest at 3.618" in length and .561" wide. Total volume of this piece is 1.23 cubic inches with wall thickness of 2/16th".

The detail relief is smaller now that the model was re-sized to 15" from 24". The smallest height in detail is .011". Will be interesting to see if it comes out on the printer.

STL files are ready to send to printers.
Tankmodeler
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Post by Tankmodeler »

Yeah that's the right way to mould what have become relatively small parts.

Look sreally cool. I hope the prionter resolution captures the detail.
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Joseph C. Brown
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Re: Sanding foam

Post by Joseph C. Brown »

b8factor wrote:Oh I will add sanding foam(both styro and blue foam) is a PAIN! I bought a charcoal paint respirator and full goggles to wear while doing it since the dust is so fine! I see I should have gotten a paint coveralls as well! Fix that this weekend.
I had read a magazine article written by modeler who'd scratchbuilt a Von Braun style rocket. He did it by turning styrofoam on a conture-sander/lathe combination, and complained mightily about the mess made in that process.
When I met that person at Wonderfest a few years ago, I innocently asked "why didn't you wet-sand that foam? Doing that would have virtually eliminated the mess." He implied that styrofoam was just an experiment for him, and only good for amateurs to use... well, that effectively told me that he didn't think of it (wet-sanding) at the time - but wasn't about to say so to me. But, I could be wrong. :D

....
To wet-sand foam, use a sanding block:
http://3mcollision.com/3m-rubber-sandin ... 35519.html

And *appropriate* sanding material, either wet-or-dry sandpaper or dry-wall sanding screen. Put down some newspapers under your work area. Fill a small dish part way with water. Make sure the dish is large enough for the sanding block to be dipped into.

Now, wet-sand the foam. You will note that the level of sheer mess has gone down by over 95%.
b8factor wrote: ...a box fan at the window sucking out the smoke and fan behind me blowing the smoke to the box fan I have completely eliminated the fumes from building up in the hobby room.
Glad to hear you are doing that! Toxic smoke from melting foam: bad. Ventilation: good!

:8)
________
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Post by Mad-Modeler »

Hope that fan is strong.

When I learned airbrushing , etc there was a golden rule.

If you can smell it with the mask on it is already deposited in your lungs, which don't have a self-cleaning feature.
b8factor
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Post by b8factor »

Mad-Modeler wrote:Hope that fan is strong.

When I learned airbrushing , etc there was a golden rule.

If you can smell it with the mask on it is already deposited in your lungs, which don't have a self-cleaning feature.
Oh yeah i can not smell it. Well to be fair I have a respirator and safety glasses on in addition to the two fans! I am a bit paranoid about gasses!
b8factor
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1st 3rd printed!

Post by b8factor »

I think it came out pretty good. White is hard to photo at night, but this is what I have.

http://img5.imageshack.us/img5/1070/ship1.jpg

http://img692.imageshack.us/img692/5496/ship2o.jpg

http://img121.imageshack.us/img121/4151/ship3i.jpg

http://img651.imageshack.us/img651/2783/ship4.jpg

http://img259.imageshack.us/img259/4743/ship5b.jpg

My impression in person is it will need some sanding but not much. The edges, both on each part and the joining edged, are very sharp (as in fine detail).

It looks like there was one hiccup with the printer in a not so noticeable spot that will need to be touched up.

More specifics will be posted after i work out the 3ds height of the detail relief and what the actual height on the model came out to be but I am quite impressed.

-B
b8factor
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degassing

Post by b8factor »

Any comments on these instructions?
http://www.squidoo.com/how-to-build-a-v ... -degassing

I was thinking of trying to build this and just wondering if I am setting myself up to fail or not? ha

Also, any tips on sanding the 3d printed parts? I have dremel with every sanding and polish head known to man. My gut was to try this on the back side first.

Or should I be doing this by hand?

Also any ideas on sanding the fine lines and 90degree groves? Was not sure if they make tiny sanding tools with perfect 90degree angles?
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:)

Post by b8factor »

Tankmodeler
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Re: degassing

Post by Tankmodeler »

b8factor wrote:Any comments on these instructions?
http://www.squidoo.com/how-to-build-a-v ... -degassing

I was thinking of trying to build this and just wondering if I am setting myself up to fail or not? ha
Seen it work before, so the fundamentals are fine. Make sure you use a pressure vessel of some sort as it says and not a standard pot or bucket.
Also, any tips on sanding the 3d printed parts? I have dremel with every sanding and polish head known to man. My gut was to try this on the back side first.
Oh, dear ghod, don't use a power tool at all!
Or should I be doing this by hand?
First run a fingernail down the surface to see how large the ripples in the surface are. It will give you an idea of what you are trying to "fix".
Then apply a couple reasonably thick layers of spray automotive filler/primer and let it dry completely. Then start sanding and scraping. Use a sanding block or everything will have a rounded edge. Use nothing coarser than 400 grit and the final sanding should be better 600 or better. Sand wet. Be prepared to scrape the small areas that you cant really sand. Sand down to the point where the tops of the layers just start to peek through. When you can't feel the layers then you're done. Don't sand the printed model directly without the primer/filler because you'll be making it undersized.

Given all of the panels & detail, be prepared for this to take a very long time. Take that time and be patient. You can easily bugger up a nice model by rushing this phase.
Also any ideas on sanding the fine lines and 90degree groves? Was not sure if they make tiny sanding tools with perfect 90degree angles?
You can get microsanding sticks & regular sanding sticks that can be trimmed with scissors or a knife to get into a lot of small places. Scraping is also a great way to get a smooth finish where you can't get the stroke distance to sand properly.

Paul
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b8factor
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Post by b8factor »

Thanks Tank!

yea, I know all about the, "take your time", haha. I know I appear spastic but in reality I go the LOOOONNNGGG way around almost every time.

e.g. I have 3 asteroids now, all waiting for me to apply 3 different outer coat surfaces and was going to paint 3 different ways. This is just to find the one I like best.

I will order some micro sanding blocks and force myself to do 1 tiny panel at a time and put down afterwards. That usually works for me to concentrate on what I am doing and not spiral out of control.

I am a bit concerned about molding this now that I created some hefty undercuts with the bottom fin. I should be able to figure something out but I am also not opposed to re-printing this part. The digital artist and i are going to sync up on what the detail relief height is in 3ds versus what came out of the printer and will probably add just a pinch more to it to pronounce some of the detail. These two parts were under $140. which is way in my budget for the entire ship.

I am glad I went down to 15" though, the ship is going to be plenty big enough at 15", 24" might have been a bit much!?! :O

-Billy
Tankmodeler
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Re: :)

Post by Tankmodeler »

b8factor wrote: Hmm, wonder if I just messed up.... want to mold these two pieces and i see even in halves I have a massive undercut if I try to mold create the mold line on the flat bottom. See picture 2 and 5.

Figure something out.
No, no, those undercuts are minor. Really minor. This isn't an injected kit, the resin part will come out of the mould really easily. The side opposite the undercut will come out first and then the undercut will come out of it's pocket easily. Bending the mould gently will ensure there's no issue at all.

Get the surfaces smooth and it's as easy as pie.

Paul
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b8factor
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Back on track.

Post by b8factor »

The 3DS 2/3 of the Star Ship rendered below. The first 1/3 has been printed. The 2nd third is at the printer now. Only 1/3 left to go and cast/molding can commence! :)

http://img33.imageshack.us/img33/4912/6f77.jpg


On a side note, and I am sure this is old news here, but Modeler got a new printer! See Example below. I opted to have my piece printed on the older printer since 1) the first 1/3 was done so. 2) The relief detail was created with the old printers specs in mind anyway 3) I simply can not afford to print the entire ship with the new machine, haha.

But I look forward to seeing some neat things coming from 3d printing int he future!

http://img199.imageshack.us/img199/6088/jwe6.jpg
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Progress

Post by b8factor »

Second set of prints done. Here is the front 2/3rds of the Battle Cruiser. The color difference you are seeing is the grey filler sprayed on the front half prior to sanding the printing imperfections.

Look at the ship broken apart and you can see it is difficult to find the seam. :)

We have the largest rear section to go with an detachable bridge and antenna. The thrusters will be a separate part that will fit when rear left and right are joined. This will allow a different material to be used for molding so the area can be clear to allow light system to simulate red/orange glow of thrusters.

http://img7.imageshack.us/img7/5474/uesj.jpg

http://img542.imageshack.us/img542/3561/ieou.jpg

http://img203.imageshack.us/img203/8581/m0uk.jpg

http://img801.imageshack.us/img801/1813/m36y.jpg

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Tankmodeler
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Post by Tankmodeler »

That looks pretty sweet. Do you know what layer thickness was used for printing?

There will be some clean-up, to be sure, but it looks like it will come out really nice. I would recommend a couple coats of spray filling primer and then gentle sanding/scraping to get smooth surfaces.

It looks like it should cast really easily, but pressure casting is the way to go to get nearly flawless castings. It will pick up every little line or flaw in the master, though, so you have to be carefull and repeatedly prime & sand to get the master really smooth.

Paul
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b8factor
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Post by b8factor »

Tankmodeler wrote:That looks pretty sweet. Do you know what layer thickness was used for printing?

Paul

I did at one time, I do not remember now. I had them do it with the same printer that the firs piece was done.

Cannot wait to get the last printing round and get them all together. :)

Be updating soon...
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Post by Mr. Badwrench »

Neat design. looks like you've got a lot of clean-up work ahead of you.
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Post by b8factor »

Mr. Badwrench wrote:Neat design. looks like you've got a lot of clean-up work ahead of you.
I do indeed and am trying to research the best way to do clean up. Unfortunately most DIY show how to polish larger items... this thing is very intricate in detail and I am having trouble seeing how to polish and sand the tiny surfaces.

Currently I have sprayed sand-able filler on the surface and started with a 600 grit but I may need to go lower. I am trying to find a good TINY sand stick I can use to get in the nooks and crannies.

Any suggestions on methods or tools to use?
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Post by Tankmodeler »

Frankly I'd start with 400 grit to get down to a basically smooth surface and then switch to 600 grit to finish it off. It will rediuce the time you are spending hugely.

There is no need to polish the surface, just get rid of the sirface texture and generate a nice random pattern on the sirface by constantly swirling and varying the abrasives.

As for tools, you could do worse than thsee products:

http://www.flex-i-file.com/flex-i-file.php

While nail sanding sticks are similar, they don't come with properly graded abrasives and the foam base of teh Flei-i-rile sanding sticks/pads make them easy to trim with scissors or knife to get into smaller areas. Using a flresh No 11 blade as a scraper os also a good way to generate smooth surfaces in small spaces.

No matter what you use, thuogh, it's gonna take a wile and get tedious. :-)

The true bane of 3D printed parts is the inevitable cleanup.

Oh, use sanding blocks instead of sandpaper in your hand to do the larger areas as it prevents rounding of corners and really helps make smooth surfaces.

Paul
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