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#76 Re: Life support systems » 3D Printers » 2012-01-26 08:42:44
Glandu-
With molds. Can be throwable low-resistance wooden molds, but you need something solid to keep it in one piece while it "dries". There are many variants, especially for composites(usually a thermoset matrix with a cloth "reinforcement", cloth can be kevlar, carbon, glassfiber...).
In other words, useful only for series. Much smaller than for thermoplastics(where molds for small pieces are steel monsters), yet, for one single piece, usefulness is limited.But, you don't need a huge amount of force to get it into the mold? I was picturing a high-ish pressure needle(Not necessarily so fine as a needle, but similar design. Call it a hose if you want, you get the idea) injecting molten plastic resin into a mold. Is that a reasonable mental model for the production of shaped pieces out of thermoset resin?
That's for thermoplastics. The question was about melamine, a thermoset. Thermoset are far more liquid(therefore you can't extrude them), and don't need steel monsters that thermoplastics require.
Also, thank you for your explanation of extrusion vs. molding. That makes things a lot clearer to me. I would hazard a speculation that research into themosets might be beneficial to 3d printing, seeing as you can get it to set using a laser or other heating device.
I'd say it is highly speculative. the risk is to have an unbalanced heating, that would make some parts solid much before others. Result would be an unreliable piece. Current processes require a mold, because a proper heating/solidifying needs time(in minutes) at not too hot temperatures(best thermoset die at 1000°C in 12 s, IIRC. They are used for military missiles, iirc). Some processes even require hours of heating under pressure(autoclave).
At least, thermoplastics cool down & solidify must faster. That's why their potential for rapid prototyping is IMHO superior. Even if this machine found by Louis is probably still far from our specific needs(but info is scarce, & reliable info inexistant).
On cables/wiring: Firstly, there is simply no reason to import this. It requires a simple ability to process metals (I would think Aluminium would be used on Mars in preference to Copper, seeing as it's not too much less conductive and is much more readily available, plus Martians are not going to be sending power over very long distances. If Copper is discovered I will definitely revise this because Copper is easier to get from ore, but this is not expected AFAIK), as well as the ability to make electrical insulation, which is necessary anyway. I think we might want to make a distinction between inside and outside, and perhaps a further distinction, when inside, of "wet" or "dry" environments. These of course present very different challenges in terms of the materials needed to insulate the cables.
100% agre with that part. Aluminium is heavily used here for medium-powered cables. I did work in a mill making cables for going under the streets & feeding houses. Most of their products were in aluminium.
Outside, the biggest danger is that someone is going to get electrocuted through their spacesuit when they're trying to manipulate the wire. Though spacesuits will probably be of the mechanical counterpressure design, which tends to be made of materials which are not conductive of electricity, we don't want to risk it. Therefore the most important thing is that the insulation be, well, an insulator. It should also be capable of functioning at low temperatures. I would suggest that a cloth woven of basalt fiber would be more than sufficient in this function.
To be tested...
Inside, there is of course the worry about fires caused by water penetrating a cloth that is not watertight. I would suggest that wires in most places are unlikely to see water, but nevertheless it is worth worrying about for all pressurized areas. I think basalt fiber-silicone composite is perfect for this, seeing as the silicone is easy to form around most anything and is relatively flexible, which is a good thing for wires.(.../...)
Inside you've got air. Air can't be 100% dry(or people will be sick). So you need something water-resistant. BTW, why do you want a composite? The interest of fibers outside is that you don't need a f****g plastic/silicone. Once you need it, I'm really not sure of the value of the fibers. If you want to shock-protect your cables, you can round the fiber over the already insulated cable. 1000 times easier.
#77 Re: Life support systems » 3D Printers » 2012-01-25 03:57:46
A couple of observations:
1. I would think we would wish to avoid use of plastics out in the open - surely the primary uses would be indoors to begin with?
2. One thing we wont be short of on Mars: energy. If we do use plastic outside, it will probably form part of objects which can be kept heat throughout the sol.
1. Well, do you need electric cables outside? Do you need to protect them? Are you able to protect them without plastic?
For the rest I agree. But the specific point of cable protection is really complex.
2. I don't understand. Sun is scarce, solar panels are complex to build on site, nuclear has a few difficulties by itself, & everything in the base will be energy-eating.
#78 Re: Life support systems » 3D Printers » 2012-01-24 06:08:03
Plastics used outdoors on Mars are going to be susceptible to rapid UV damage, without some sort of opaque coating. Indoors, just like here, pressurized or not. TiO2-white or C-black paints work pretty good here, on kit-built glass-polyester/vinyl ester and glass-epoxy airplanes.
black carbon is a standard protection against many things, including UV. Of course, your product is black, then. Though I don't know wether it's enough for Mars specific conditions.
The cold is bad for plastic items, too. Most of the materials I know get rather brittle below glass transition temperatures that are not very far below room temperatures here. Sort of like our winter temperatures. Mars is a lot colder.
That is heavily dependant on the kind of plastic you are using. Polyprolylene is brittle at 0°C/-10°C. Polyethylene between -80°C & -120°C.
Reinforced plastics would do better in the cold, but that's not extrudable or 3-D printable. You're talking hand layup in a mold for that, like building canoes out of fiberglass. Whether you bag-compress it or not depends on the materials. Vacuum-bagging makes really nice carbon-epoxy panels.
GW
Reinforced thermoplastic is still in danger in the cold, if the matrix itself is in danger in the cold. Little less, but I wouldn't take that kind of risks(and needs a huge pressure to be molded). Reinforced thermoset(which is, I think, what you have in mind, correct me if I'm wrong), as you say, also needs a mold.
#79 Re: Life support systems » 3D Printers » 2012-01-23 08:23:46
Glandu (Still have the urge to call you El Slapper, even though it's been almost two months that Newmars has been back)-
As always, your expertise in the matter is much appreciated.
Thanks. You can call me el_slapper, or slap, as you want. Maybe I'll update my sig. I just switched pseudos so that there is no database problem if one day the rest of datas is loaded back. (I'm probably dreaming wet, here).
wrt Thermosetting polymers, I suppose the problem is that I lack knowledge of the methods usually used on Earth. How are thermosetting polymers usually formed into objects in an Earth-based factory?
With molds. Can be throwable low-resistance wooden molds, but you need something solid to keep it in one piece while it "dries". There are many variants, especially for composites(usually a thermoset matrix with a cloth "reinforcement", cloth can be kevlar, carbon, glassfiber...).
In other words, useful only for series. Much smaller than for thermoplastics(where molds for small pieces are steel monsters), yet, for one single piece, usefulness is limited.
I would not be surprised if silicone is not recyclable. After all, there seems to be little reason why it would be. Standard procedure will probably be to extract the silicon and either burn the rest (e.g., the methane) or send it back through the chemical production facilities.
can't answer for that, sorry.
I don't doubt that metals will suffice in a wide variety of applications. They are, after all, stronger, require less energy to produce (per kilo, at least, probably not per liter), and sound like they're much more workable, especially at a smaller scale. Nevertheless, I'm sure some need for plastics will remain so I would like to have some options available.
yeah, I had a looong post about cable protection. for that you need extrusion. Different variants possible.
Also, it occurs to me that it will probably be impossible to recover the acetic acid when silicone is being used as a caulk. It happens, I suppose.
Silicones are a special matter. Can't answer here either.
Oh, and quick question: Would extrusion molding be quicker if it were done at Mars ambient temperatures, for example by extruding into liquid CO2?
ahem. "extrusion" & "molding" are contradictory. That's the beauty of the aforementioned 3D printer(even if the final quality is something I have doubts about) : it makes pieces like if they were molded, with extrusion & without mold.
Normally, extrusion makes profiles. Like a window frame, or a cable, or a tube, or a wire..... This thing we have here is the first news I have of dynamically altering the profile while extruding. It has a lot of potential.
Now to answer your question. I did personally extrude tubes(5 cm diameter) at 30/40 cm/second. It works thanks to the extreme viscosity of extrusion-dedicated grades of plastic. Ours was overcrowded with chalk(up to 60% in weight, it reduces a little mechanical resistance, increases somewhat the weight, & lowers prices a lot); without it, it could even go quicker. Mars-like temperatures could help going even quicker(but do we need industrial production rates?), but with risks upon quality(nothing definitive I'd say).
Where I did have doubts, is for thermosets. Those ones need to be heated for solidification instead of cooled down, and the process is slower. Martian cold can't help there.
#80 Re: Life support systems » 3D Printers » 2012-01-20 04:38:35
Glandu-
I wouldn't be surprised if a thermosetting polymer could not be properly formed by extrusion or injection or many of the other methods which are traditionally used for polymers. On the other hand, wouldn't a thermosetting polymer be possible to form via more traditional measures, as used for metals, e.g., by pouring (perhaps pressing, I suppose, depending on viscosity- which reminds me, it's technically "viscous"- I had almost forgotten you weren't a native speaker of English, haha
), and then heating it to make it stay in that shape?
"pouring" & hardening after is the exact principle of extrusion. Just, "hardening" is done by cooling down, not heating up(works for thermoplastics, lead, & probably other stuff). "hardening" by cooking seems unlikely to me, as it's a longer process : you modifiy the chemical structure of your atoms, instead of simply freezing them when you go the cold route.
I don't say it's impossible, just I haven't heard anything that makes me think it's a good idea. And I've heard a lot.
Silicone is generally not too useful for shaping into specific objects, so far as I know, though I have definitely seen kids' toys which were made of silicone rubber. I'm not quite sure how that was done. The general process for the manufacture of silicone involves treating Si(CH3)2Cl2 with water, leading to a reaction which produces silicone rubber and HCl. There is apparently a slower alternative method which uses acetate and produces Acetic acid, but this is from wikipedia so I can't even verify my memory at present seeing as English language wikipedia is down to protest SOPA and PIPA. I would add, though, that if it is possible to do with acetic acid, it should also be possible with methanoic acid (Common name: Formic acid, IIRC), but on Earth I believe the two-carbon organics are actually generally cheaper than the one-carbon, because of the wide availability of ethanol. In this case, I suppose we would have to ask ourselves which is more undesirable- methanoic acid or hydrochloric
As always, chemical is only half of the way.
Silicone is particularly good for making seals, seeing as it functions as a caulk on Earth. Whether it will later be possible to melt down and reform I can't say. I would use the thermosets for objects which need to be shaped.
The only recycling known for thermosets is to burn it(and get the energy). But they require less heavy machinery than thermoplastics, usually. Silicone, from what I did read, seems not really recyclable either.
How much do you know about the properties of melamine resin, in terms of strength and other relevant properties for parts made from it?
IIRC, that's like standard plastic. Just, obviously, more heat-resistant, & less shock-resistant. As any thermoplastic or thermoset(besides polybenzimidazole, a bitch to produce & to shape), it's really weak compared to good old steel.
My 2009/2010 posts about plastics(inspired by highly optimistic polymer plans of mars homestead) have disappeared, yet I still think that good old steel should be enough for most uses : easy to shape with very few machines and resistant to everything. Of course it's heavy, but it's only 38% as annoying on Mars than on Earth.
#82 Re: Life support systems » 3D Printers » 2012-01-17 04:34:43
Ah, at least someone who understands my doubts(and goes even further). Someone who really works in the domain, seems like. I feel less alone.
Just, this specific machine possibly could do things that machining couldn't do, i.e. complex shapes inside the piece. In one single piece. That's not a common need, though.
But, other than that, I tend to agree with you : better machine 19th century fashion - with 21st century control.
#83 Re: Life support systems » 3D Printers » 2012-01-16 09:22:26
No - I wasn't counting on recycling plastic.
That's good, as plastics are not very good a it, & that's bad, because everything will be scarce on the red planet.
But extrusion is part of the process for all types of plastic I believe, or most anyway, so I thought it was good to see it being done on such a small scale.
Nope. It's one method amongst many. Injection is usually the method used for complex parts; there is also thermoforming & rotomoulding. All those methods require complex, dedicated moulds, and are therefore not very useful for our needs. Extrusion, on the other hand, is ideal for making straight parts, i.e. with a profile that does not change(like tubes).
What is new to me in this method is the ability to reach complex forms without a dedicated mould. This is definitively new. But We lack accurate informations on the real quality of produced things.
Remember, this is all home made stuff/assembly and he seems to have come up with a v. professional looking product.
That's the problem with non-trained engineers : they tend to take "looking" for "real". What we need to have an accurate idea of the real potential of this thing is not easy to see : dimension tolerances, mechanical resistances, shape limits. Those things are important. remember, we don't go on Mars for building toys. We will need high-quality technical pieces, & that's another deal. Can this machine fulfill? Their marketing blahblah does not give any answer.
Even if the answer is no, that's a nice little machine, by the way... I'd love one at home(no place for that unfortunately).
For me, I am revising my proposals, and will now include polymer production. We can certainly get the hydrogen and carbon from the planet.
As said by others, complex. Worth it? No clue, unfortunately.
And silicones & melamines are different babies than polyethylene when it comes to transformation. Melamine is a thermoset, not a thermoplastic, and therefore more liquid before transformation. I highly doubt you can extrude melamine(and I'm pretty sure). For silicones, a quick search didn't give me enough elements, but my long-term memory makes me doubt it could work for them also(but that's an heavy uneducated guess).
Which made me reread the BBC article. I think there is a mistake. They speak of 40mm per second, and 20 minutes for making a small piece. Must be 40mm per minute. Or 20 seconds for making the piece. It would lead to radically different conclusions.
==>If it's fast, then it's nearly like real-life extrusion, & you need a very visquous(spelling?) kind of polyolefine. It makes having the right polymer on Mars rather tough. If profile does not change suddenly
==>If it's slow, it means they have some special behaviour to pass correctly through the end & keep everything at the right temperature. Internal structure of the piece must be rather strange, garbled, & mechanical properties rather ugly. At the same time, accuracy of the piece must be greater.
Conclusion : I'm teased. I need to know more. Aaaaargh. Plus I'm at work & can't check youtube. Aaaaargh again.
#84 Re: Life support systems » Cold fusion (LENR) is for real - NASA says so » 2012-01-13 05:21:01
Couldn't find the link on NASA website. I smell a trap(not from you, Louis). Maybe I'm wrong. But the scientific training I did receive did include a lot of "double, triple check it, wether you sure it's true, or wrong".
Single Youtube link is not enough.
#85 Re: Life support systems » 3D Printers » 2012-01-13 05:16:14
At the same time, you shall remember that each transformation (especially extrusion) significantly reduces the mechanical resistances of pieces you make. Recycling is not really an option, there.
Can be useful, but don't count on it for technical pieces.
#86 Re: Human missions » Developing the cis-Lunar economy and infrastructure » 2012-01-13 05:11:55
I wonder how hard it would be to drape a light fiber optic cable across the surface of the moon as your land or take off. The from the deepest dark side base it would still take less than 2000 miles of fiber to reach the near side and setup a direct surface station.
mmmh, that would be an heavy baby to launch, transport, & deploy. Here on earth, it's already a tough job; you need a vehicle(truck or ship), skilled specialists, & probably a few other things. On the moon, the lack of proper mastery of the field would add, IMHO, a lot of headaches. A few sats would, I think, be muuuuuch easier.
#87 Re: Life support systems » 3D Printers » 2012-01-12 08:57:50
From far, looks like polyolefines. i.e. polyethylene or polypropylene. I might be wrong, though. Impossible to be sure without burning & smelling the damn thing(which I don't know to do anymore). If it smells like a candle when it burns, then it's polyolefines.
#88 Re: Life support systems » 3D Printers » 2012-01-12 07:22:07
Unlike previous 3D printers, this one seems like it might be something else than complete waste. Huge difference is : extrusion. All other printers I've been shown before wer just making heavy layers of unusable crap. With the right shape, & everything else(including mechanical properties) wrong.
I still do not buy the "can nearly replicate itself". By extruding, you can only form materials that are not heat-resistant. For extruding, you need a heat-resistant screw. And, of course, I fail to see how to make the electronics needed for converting bytes into movements.
Other limit is the mechanical quality of the made pieces. Can't be as bad as layered printing, yet extrusion is a tricky to properly balance - especially on asymetric pieces. The cooling down of the piece also has a strong effect on wether it will have good mechanical properties. For toys(the current application), it does not matter.
Anyways, I miss more accurate details to decide wether it can be useful. Yet, it might be. That's the first time I see a 3D printer that I don't dismiss at first sight. Cool.
#89 Re: Human missions » Mars Direct 2007 » 2012-01-09 06:13:51
There's far more place available in modern submarines, especially nuclear ones; staying stacked like sardinas Uboot fashion is tough but doable for week-long missions. It is no more for month-long missions.
My uneducated preferences goes to inflatables, both for travel & on site.
#90 Re: Meta New Mars » The great crash » 2012-01-05 04:30:07
Nah. If you have a bunch of professionals, like a bank has, it's safer to store on your own server. If you just have amateurs on their free time, the cloud is thousands times safer. Not as safe as they claim, but at least they have professionals concerned with the safety of datas.
#91 Re: Human missions » Could a small scale experiment work for life on mars???? » 2012-01-02 08:15:02
Or we need giant mirrors to feed our plants with more light. Kind of aluminium sheets, no need of heavy things. If we go the "under roof" road, collecting the light & transmitting it through glassfiber could be useful to spare other sources of light/energy(to be studied, just an idea that comes like that).
#92 Re: Not So Free Chat » Happy Birthday JoshNH4H » 2011-12-30 08:08:37
Well, Toulouse is not far From Spain. But I understand : SpaceX is where things will happen, & better go where stuff happens.
#93 Re: Human missions » Developing the cis-Lunar economy and infrastructure » 2011-12-30 07:51:04
+1 with GW on the last point. Though it depends on the polymer, resistant polymers are usually no the kind that are useful for other purposes. Most polymers are heat-vulnerable, cold-vulnerable, light-vulnerable. For radiations I'm less sure, but the very nature of polymers chemical structure makes me think most polymers are radiation-vulnerable too.
#94 Re: Human missions » Can you tackle Evolutionary Algorithms ? » 2011-12-26 07:40:26
and a lot of traps. I'm not bad at program development, but those things are awfully complex. I think we'll need a programming langage better than what we currently have for pushing those theories to their full potential.
Right now, it only works on extremely narrowly defined problems, with a lot of work & patience.
#95 Re: Science, Technology, and Astronomy » The fusion age has begun. » 2011-12-06 04:25:05
Trap is, 99,99 of parralel thinking is bullcrap or misunderstanding, & it's rather tough to distinguish the real added value in the middle of the crap. Geniuses see it before anyone else(and it usually requires a lot of determination from them).
Of course, I'd love to see it work.
#96 Re: Human missions » Mission One: a one way ticket to Mars? » 2011-12-02 09:58:04
Hop has been quicker than me. You can make perfect-looking bicycles witha 3D printer - that weight 80kgs or so. With a mediocre mechanical resistance. 3D printers are crap for anything else than prototyping & marketing. Useful on earth, but not on Mars, I fear.
The shape is not the only important thing in a mechanical element. The way it is done as a deep impact upon the mechanical resistances, and therefore upon the usability of the element. In your car engine, the carter is molded, but the piston is machined. Because they have different requirements, and each process is the best adapted to the usage. We need machines, forges, and other metal-transforming elements for making efficient & reliable equipment. 3D printing sucks for our needs.
And starvation can come quick. A little damage made on the food-processing equipment, and you end up as viking Groenland. They ate their dogs, and even small birds, but it did not save them.
On Mars, you don't have a spare environment - like Groenland in the late 1300s when cooling climate cut them off norwegian trade ships. If your environment fails you, you're dead. Man-made environments are different from nature-made, but can be as vulnerable. Of course self-sufficiency is desirable for any Mars settlement(and I'm here because I believe it's doable), but it's by no way a safety guarantee. For such an outpost(and it will be an outpost for centuries, at least, bigger & bigger, but still an outpost), lack of homeland support is a great danger. As Hop said, there is no Home Depot on Mars. There is no supermarket, there is no easy mining, there is no easy access to water, soil quality for growing food is unknown. That's even tougher than Viking Groenland, as there will be no grass to feed the cows.
#97 Re: Human missions » Mission One: a one way ticket to Mars? » 2011-12-01 03:44:40
Pfft. I find it unlikely a country on Terra would wish to sustain a "colony" for several centuries, or be able to. Sending people there without any desire to build a colony or have any kind of self-sufficiency is stupid.
Well, that happened a lot in human history. European colonies that did survive in the Americas were heavily backed up by their powers, for decades, or even centuries, as long as they did provide something in exchange. Viking Groenland went extinct int the early 1400s when they lost their cotact with Norway. French and swedish colonies in Brazil had the same fate.
Takes a long time and a lot of money to make a settlement viable, and usually they are viable only through trade, even after centuries. Viking Groenland had no metals, & did buy tools in exchange for luxuries(ivory, falcons, bears). Even today, many of the French possessions overseas are heavily dependant from food & industrial stuff from the motherland. Pitcairn, the island of the Bounty mutineers & their polynesian wives, was about to starve when it was saved by the british navy resupplying it with tools.
I find it unlikely for a Martian colony to survive infinitively without exchanges with the homeland. Too many things are needed for survival, and it needs a huge country to have them all. On earth, no country has them all. China lacks petrol, all others lack rare earth elements. Modern economic needs both.
#98 Re: Meta New Mars » Spammer » 2011-11-30 03:43:54
Glandu- Ideally, it would be something that every human would know, but no spambot. Perhaps a logical catchpa, or something?
could be. The thing would be that it would be a lot of questions, be it "is the triangle blue or green?"(while embedded in a red square) or "who was the first Russian in space?". But if there is only one answer, bots will always answer "Collins". So my first idea, I fear, was not good.
Could be always the same question - but that changes often, maybe every day or two. That would be a tedious work to make them, though. I'm not sure, though. Those who work with brute force would break any question.
#99 Re: Space Policy » The SLS: too expensive for exploration? » 2011-11-29 09:41:26
Folly? The guy voting that will be reelected. That's perfectly rational.
Or not 
#100 Re: Meta New Mars » Spammer » 2011-11-28 03:41:30
Sorry for my crappy english. I'm native french speaker, & my first foreign language was german. It's easy Wiki-able, but someone who makes the research is likely to be interested in the topic.