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back to article 3D printed guns are for wimps. Meet NASA's 3D printed ROCKET ENGINE

Weapons enthusiasts have been experimenting with 3D-printed guns for months, with mixed results. But NASA has set its sights much higher – quite literally – having successfully tested 3D-printed parts under the torturous conditions of rocket engines. The most recent such test took place on August 22, the space agency revealed on …

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Bronze badge

Sorry this model is out of print

It looks as though printing a fully functional gun is very likely rather than unlikely, fortunately the technology should be out of the reach of most disgruntled High School kids with a clock tower to climb.

What is more interesting is how far forward the expectations have moved in the few years that 3D printers have been going. I can see the technology developing even faster now for military/aerospace items and also the possibility for specialised parts where laminations and hardness and temper can be applied differentially as the part is being printed. Almost like printing a katana.

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Re: Sorry this model is out of print

Really, if you can buy that machine, you can source your officeworker-reaping AKMs directly. And get delivery of a few boxes of ammo.

I remember Drexler speaking about honest-to-God nanotechnology (the one with the nanobots, what nanotechnology meant before marketdroids looking for the next big thing found about it) and saying that one day one would be able to put together a rocket engine in a vat filled with the appropriate salty solution and a few grams of magic nanobot powder. Just rinse when the light goes green.

This seems nearly as good.

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Anonymous Coward

Rocket Engines?

Thought NASA had made that side of the business redundant?

Does Obama know about this? If not keep it quiet before he closes it down.

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Re: Sorry this model is out of print

"Really, if you can buy that machine, you can..."

Sure, the cost of a additive metal-based printer might be prohibitive today, but what about tomorrow?

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Unhappy

Re: Sorry this model is out of print

"I remember Drexler speaking about honest-to-God nanotechnology (the one with the nanobots, what nanotechnology meant before marketdroids looking for the next big thing found about it) and saying that one day one would be able to put together a rocket engine in a vat filled with the appropriate salty solution and a few grams of magic nanobot powder. Just rinse when the light goes green."

Yes. That was in his doctoral thesis.

In 1986.

We've been waiting for the future for a long time.

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Re: Sorry this model is out of print

"..In 1986. .. We've been waiting for the future for a long time... "

You seem to forget how far we have come.

Chances are that at this very moment you're holding a miniaturized quad-core computer with a very high resolution full color display and capable of receiving and sending digital and analogue communications at lightning fast speeds with others of its kind for many hours continuously. Yes, that would be your mobile phone and most people can't even being to imagine life without it.

In 1986 they would need several rooms full of supercomputers to achieve what you hold in your hand right now.

I believe what mr Drexler described is what he believed to be the ultimate end-goal and achievement of technology. It's simply the limits of his imagination at that time.

Why don't we ask him today, no doubt he will come up with a whole new fantastic view of the future.

The point being that you can't predict what tomorrow will bring. Who ever imagined we could do all the things we can today?

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Meh

Re: Sorry this model is out of print

>We've been waiting for the future for a long time.

That's the thing about the future, it's always off in, the future...

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Joke

Re: Sorry this model is out of print

nanotechnology meant before marketdroids looking for the next big thing

Nanotechnology, the next big thing!

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Meh

Re: Sorry this model is out of print

"You seem to forget how far we have come."

Processors will get faster.

Screens will get better.

Mobile phones will get smaller. Sorry to burst your bubble, but they did exist then.

Windows will still be a PITA.

That's called an "extrapolation." 27 years later what do we find?

Now a machine that can sit in your closet that can make anything you need from an adequate supply of raw materials, which could be just a mound of soil, was revolutionary.

And still is.

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Flame

That's actual NASA R&D

I thought that was dead!

Seriously though, the injector is the "hard part" of a rocket engine, and even after you've come up with a good design, machining it is a bitch. You've got to put literally hundreds of tiny holes next to each other in some seriously hard metal, plus you've got to somehow put in the channels internally that feed them all without any chance that the fuel channels can connect to the oxidizer channels. If the 3D printer can make an accurate injector in less than a month, they're pretty much printing money right there.

The turbopumps are difficult too, but the design is the rough part, they're not nearly as hard to actually make. Notice you'll not see any pictures of recent rocket turbopump impellers, they're secret, just like nuke sub props.

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Re: That's actual NASA R&D

Time to manufacture is the big one here. They can try a design mod out in a matter of weeks rather than the 6+ months of traditional manufacture. Turbopumps may not be as hard to make as injectors, but there's still a long lead on testing a new design.

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Anonymous Coward

If they can make components in space

Then Mars is a lot closer. Sending up a 3D printer into orbit makes a lot of sense as long as it can be made to work in zero gee.

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Anonymous Coward

Re: If they can make components in space

Not really, since there is no weight saving.

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Re: If they can make components in space

Actually, there is a good use for 3D printing in long-term manned flight - such as Mars missions. In-space manufacture of spare parts. Without 3D printing, you'd need to take several spares for every vital component that could fail during the journey. With 3D printing, you can ditch all the spares for solid-plastic parts (Lots of life support things - impellers, seals, valves, plungers, pipes) and just take a 3D printer and a supply of feed plastic. Potentially that can mean space and weight savings.

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Re: If they can make components in space

The weight saving comes from the fact that you only have to send up one general purpose tool to manufacture your parts rather than lots of specialised tools. I'll admit it doesn't make much sense for things like Earth orbiting space stations but it does for planetary colonisation. If we're going to colonize Mars it makes sense to set up mining and ore refining operations. The manufacturing that follows is a lot easier to set up if you only have to send one type of general purpose tool.

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Happy

Re: If they can make components in space

" I'll admit it doesn't make much sense for things like Earth orbiting space stations but it does for planetary colonisation."

I'd bet you'd wouldn't say that if the urine re-cycler had broken down again and the last spare to fix it was used 3 months ago with the next scheduled in 2 months.

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Meh

Re: If they can make components in space

>The weight saving comes from the fact that you only have to send up one general purpose tool...

Only if the raw material for the other tools is available at your destination, because if you need to build a tool you need the plastic and its mass doesn't change just because you change its form.

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Stop

Re: If they can make components in space

Actually its does change the mass requirements in 2 ways. Firstly feedstock will probably pack tighter than lots of funny shaped spare parts. So more space opens the potential for more usable mass.

Secondly your failure requirements become different. Rather than having consider the MTBF off all components and take 3 of this and 4 of that - all you have to worry about is the aggregate MTBF of anything made from 3d printed material.

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Coat

Re: If they can make components in space

Remember to take a *spare* 3D printer into space with you for when the first 3D printer breaks ;-)

It's 3D printers all the way down!

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Re: If they can make components in space

>...pack tighter than lots of funny shaped spare parts.

You're confusing density with mass...

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Anonymous Coward

Re: If they can make components in space

Providing you have plenty of energy to power the 3D printer and the raw materials taken up there combined with the printer itself weigh less than the sum of spare parts.

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So SLS engines made with SLS? Paint me impressed.

Mind you, it's a cryogenically fuelled rocket engine. You could build it with some guy beating a hammer on some metal and I'd still be impressed.

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Showerhead test

Hot-firing is impressive, but the important test is the "showerhead" test, where they pump fluid through the fuel and/or oxidizer channels and give it the really hairy eyeball with lots of high speed cameras to make sure the jets impinge on each other properly, and nothing is squirting off somewhere it's not supposed to. That's where you usually go "aw crap, this one is junk" or not.

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The point isn't printing rocket engines...

...it's printing spares.

A mission to Mars (or a Martian colony) wont be able to send back to Earth for replacement parts. They MUST print their spares, and it must work even when the part is as difficult and critical as a rocket engine.

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Anonymous Coward

Re: The point isn't printing rocket engines...

Agreed. Although I could see an advantage on the ISS as well (weight savings of having the printer + raw materials on board versus all possible spares). Even on Earth, navy vessels could benefit from reduced need for spares stocking.

Now the real key on interplanetary transport: will it make a cuppa tea without hogging all the resources of the ship's computer?

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Re: The point isn't printing rocket engines...

A cup of tea With milk!

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Re: The point isn't printing rocket engines...

"...almost, but not quite, entirely unlike tea"

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Re: will it make a cuppa tea without hogging

Yes, but only if you first both have and do not have tea when you program the computer.

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patents patience

The major patents on selective laser sintering run out in 2014. Expect the price to drop considerably - maybe not enough to put it in the reach of a home user, but certainly a small business.

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Boffin

Re: patents patience

Depends what materials you're using. With a lot of plastics it should be cheap to do it (I was considering open sourcing a project to build one last year that's around the extruded stuff price range). The biggest problem is finding and acquiring finely powdered plastics with good properties and safety of handling them (breathing in plastic dust is nasty).

The issue is basically making a flat surface from powdered materials and the rest you can do with a blu ray laser.

Doing it with metals in the home is probably never going to be a thing though. There will come a time when some hobbyists will do it but it'll be an expensive hobby to get into.

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Re: patents patience

"Expect the price to drop considerably"

Am I the only one here who can't read the word 'considerably' without imagining James Bond as the speaker, and gunshot and a pregnant pause beforehand?

"Expect the price to drop..." BLAM "...considerably."

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Anonymous Coward

Re: patents patience

@David W - It would have to be Connery ..

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Re: patents patience

@Nicho,

No, that would be conshiderably...

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Boffin

Errm, how hot?

> "So far, NASA says, the 3D-printed part seems to have worked "flawlessly," despite being subjected to 1,400 pounds per square inch of pressure at nearly 6,000° Fahrenheit (3,316° C)

Just which Nickel/Chromium alloy has a melting point over 2,000 C? The rocket exhaust may reach 3,316 C, but it isn't in contact with the injectors or the cooled walls of the combustion chamber. Where did you get these figures from?

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Re: Errm, how hot?

I wondered the same thing. The injectors do not get that hot. Copper and aluminum can be used in some designs. NASA has always designed for complexity. I've put together F/O injectors that were only 6 pieces. Being able to print injectors in one piece in a stable alloy is great for maintaining tolerance and consistent performance. I look forward to hearing more about the progress being made using this type of manufacturing technique.

Making spare parts is not a great factor in taking a trip to Mars. The impact on the human body is going to be a much more formidable hurdle to overcome for that venture. One major solar event and an entire crew could be lost. I would like to see an outpost on the moon accomplished first to test the technologies that we will need to do Mars properly.

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Anonymous Coward

Re: Errm, how hot?

key part of the sentence: at 1400psi

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Re: Errm, how hot?

> key part of the sentence: at 1400psi

That's a trivial pressure increase. Even if it was 1400 'Atmospheres/Bar' I doubt that it would double the melting point. I suspect that there's a journalists' conversion error involved.

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3D printed DMLS chamber march 2012

http://rocketmoonlighting.blogspot.co.uk/2012/03/more-testing.html

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Side note NASA built a 250klb pressure fed GH2/GO2 in the mid 90s.

It took (IIRC) 2 or 3 major parts, with a load of bolts to hold them together and was ablatively cooled (although they had several test fires)

If you want simple injector systems look up "pintle injector." Developed by TRW and classified for years they claimed they'd never had a combustion instability problem with it and it's what the Spacex Merlin engines use.

BTW NASA also does a lot of test firing with essentially a 40Klb plug nozzle design.

The key issue with SLS I can see is surface finish and how much surface prep you need to do to reduce friction pumping costs. Something called "liquid honing" can help a lot with this.

Thumbs up for NASA doing some actual engineering for a change.

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This post has been deleted by its author

Black Helicopters

So next time someone wants to support a group of freedom fighters they can just send them a printer with different levels of remotely-enabled authorisation ('defensive use only', 'small arms', 'larger calibre', anti-tank, ...)

Actually from this story the main benefit may come from redesigning components to make them printable.

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Anonymous Coward

"3D-printed parts"

Look, come on, isn't this just an inferior version of CAM or CNC processes, which have been in mainstream industrial use for decades?

(only difference I can see is that CAM/CNC cuts objects out of a solid block of raw material while 3D printing builds up layers of raw material. The former can produce a more robust output while the latter is more efficient in its use of raw material and better suited for rapid prototyping)

http://www.cnczone.com/forums/general_3d_printer_discussion/187092-3d_printing_vs_computer-numeric-control-processing.html

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Re: "3D-printed parts"

"Look, come on, isn't this just an inferior version of CAM or CNC processes, which have been in mainstream industrial use for decades?"

Ummm, no. Additive manufacturing can make parts with complex inner geometries (hidden passageways and so forth) in a single pass. That's why the latest injector design only contained two parts, rather than the 115 parts of the original design.

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Boffin

Re: "3D-printed parts"

On profound difference is that existing subtractive manufacturing methods do not have the capability to make intricate internal structures in a single-block product. There's no real limit to that with additive (3-D printing) methods.

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Holmes

Home 3D Manufacturing in Metal is not out of the question

The technology that is used in a high end sintered nylon 3D printer is not that difficult to extrapolate to home manufacturing of powdered metal parts. Some "MAKER" (from MAKE magazine) will have something available soon I'm sure.

Lasers have become very powerful, easily available and comparatively inexpensive. 2D CNC Laser cutting is quite simple, adding the third dimension not too hard. Laying out powdered metal verus nylon powder is not a big stretch. Modulating the laser for the right melting temperature and an inert gas bath are probably the most difficult parts. Getting powdered metal is not too difficult.

You can already buy a 3D machining mill for around $10,000 plus tooling. Expect that 3D metal printing technology will hit that price point in a few years and even lower if you build it yourself.

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