From time to time we take a look at developments including technologies as well as designs, to see if this field is progressing as rapidly as everyone originally expected it to. Today, we’ll put up the data and let you be the judge of progress.
First, New Tech in Additively-Manufactured Guns
And we have a couple of those to begin with: one all additive but the springs and grips, and one a hybrid of additive and subtractive (lathe turning) technology.
Radically Customized Stainless 1911
As everyone has read here before, Solid Concepts of Texas built a proof-of-concept .45 of stainless steel, another of exotic Inconel, and then a short production run of historic (and priced accordingly: $12,000!) printed pistols.
Solid has to tread lightly these days, having been acquired mid-2014 by the militantly anti-gun lefties of Stratasys, whose diet of “that enchanted stem, laden with flower and fruit” has cause these hermits of Eden Prairie to believe that wishful thinking, and banishment of deodands, can erase evil from the world1. But the guy who headed up Solid’s pistol projects, VP Eric Mutchler, built himself a fully-customized 1911 that he calls The Reason (as in, “Who dares argue with Reason?,” or maybe along the lines of Bourbon cannon labeled in relief, “Ultima Ratio Regum“).
We found the story when Reason Magazine (no relation) ran the story on 27 October:
It was made by him and for him, merely as his personal example of how interestingly personalized 3D printing allows metal weapons to be. (Solid Concepts, now owned by a bigger, and publicly held, 3D printing interest Stratasys, is trying to avoid being too connected with the weapons field these days.)
The weapon was made mostly out of stainless steel with store-bought grips, using an EOS M280 3D printer. It chambers 10mm ammo and features the word “Reason” printed in the slide, and the preamble to the Declaration of Independence on the front of the grip.
Some other details actually ran the day before in 3D Print.com, which is where we found the picture of the gun (we think it came from Mutchler himself). Frankly, we wouldn’t have customized a 1911 that way. We’d have customized it completely differently. Which is one of the incompletely-exploited gifts of 3D printing — the age of mass personalization. We think it would be a gas to build one in Titanium. We don’t have an EOS gathering dust in the lab, though.
Machined-steel Cartridges Extend Utility of Plastic Gun
There are several conceptual approaches to the limits of consumer 3D-printing plastics in firearms applications. You can accept the limitations of a short-lived, low-rigidity firearm. You can print the gun in metal, like the Reason above. You can seek better 3DP materials than legacy plastics like ABS and PLA. (We’re getting a demo of a printer from 3D Systems next week, that prints nylon for much more structural parts than ABS or PLA. Nylon enables a lot of things).
And then, you can hybridize a 3D-printed gun to use a metallic (or carbon fiber, perhaps) insert of some kind. There’s a new design that’s conceptually similar to Cody Wilson’s original Liberator, but that uses heavy-duty steel cartridge cases to contain a lot of the energy of firing. Brass cartridge cases remain popular a century and a half after their initial adoption because of their excellent obturation, but neither they nor any of the alternative materials provides any strength; that comes from the barrel and breech or cylinder. A cartridge that provided strength as well as containment and obturation would be wastefully heavy, but ought to work in a flimsy gun.
Michael Crumling is a machinist who has developed such a product, which he calls the .314 Atlas. This has produced a lot of hyperventilating in the so-called tech media like Wired and The Register, which amusingly insults Wired with supercilious British contempt for gun-happy colonials like ourselves, while writing a similarly shallow article that does at least note that: “Crumling makes them using a lathe — a machine tool.”
The author of the Register piece, Lewis Page, contends that he’s a great expert on firearms because he spent eleven years in the Royal Navy, during much of which he had to qualify on individual weapons. We’re so impressed. (Of course, that means he probably does edge out the Wired guy on hands-on experience). If we ever need an expert opinion on rum, sodomy, or the lash, we know where to turn.
Crumling’s own blog, Mike’s Custom Weaponry, is worth a read. He has not released the design files for his Liberator-based pistol that he uses with the .314 Atlas. He’s keenly aware that this is not a complete weapon equivalent to manufactured firearms (which kind of takes the air out of Wired’s and Mashable’s freak-outs, and Page’s attempt to be the veritable Nelson of battles against strawmen). You may want to check his post on the .314 Atlas. It’s named, by the way, after his vintage lathe, which like any true machinist he builds parts for himself.
Future metal printing technologies
As we have pointed out over and over and over again (damn. Dave Clark Five earworm), the immense investment in physical plant and where’s-the-hydropower-dam electrical demands of the SLS and DMLS technologies used on prototype firearms today, won’t be state of the art forever. Since a lot of the key technology involved in repeatably positioning a print head in three dimensions is already mature and commoditized, it’s only a matter of time before metals printing is in hobbyist hands.
Indeed, a Michigan Tech team demonstrated 3D metal printing with a welder-based printer two years ago. And now there are at least two different new startups promising to bring low-cost (relatively) printing to the shop or office, and more new technologies appearing the the academic literature.
New Startups — Aurora Labs and Weld3D
Aurora Labs, based in beautiful Perth, Australia, hit with a splash in September, and then sank with a bubble in October. The company claims it has new SLS-like technology, which it refuses to detail, that allows it to sell for $AUD 4,000-8,000 the capabilities that 3DS sells for hundreds of thousands. It launched a Kickstarter campaign on 23 September 14, which met the company’s goals of $100k AUD in three days and soared to over $300k in a couple of weeks — before being yanked 9 October 2014. The company’s head, David Budge, told StartupSmart (an Australian tech publication):
They essentially wanted us to give them and everyone else a tour of every inner working of our machine. After various discussions back and forth it just wasn’t enough. I understand they have to protect their position and model… but I decided to pull the site down.
Reading between the lines, it sounds as if Kickstarter shut him down. The Aurora website is currently in chaos, with warnings not to use the ordering software and promises of the site being up by various dates, the latest of which appears to be 5 November 2014. If the company really has the revolutionary technology, and ability to deliver product, that they have promised, they’re a game changer. But so far, all they’ve shown is press releases, claims, and two small photos, one showing a pyramid of supposedly printed material 4mm high, and one showing a simple, flat part.
In the StartupSmart article, intellectual property attorney Brian Goldberg explains that they might be best advised not to disclose their innovations, “if there’s no [intellectual property protections] in place. … [J]ust to publicly disclose it hoping that no one will copy it … is a high risk.”
If and when Aurora rises from its present hibernation, you’ll probably see it in their Facebook timeline or Twitter feed first.
On the other hand, Weld3D produces steel parts with a crude surface finish, but can make geometries impossible (or, at least, extremely difficult) with traditional, subtractive manufacturing. The company is simply a couple of engineers in Huntsville, Alabama, working to commercialize what appears to be the arc-welding-deposition process pioneered by Michigan Tech. They’re not selling anything at present, but they’re gaining know-how that has great potential. Here’s their machine in action:
Looks like a welder to us, but it’s not joining metals, it’s building up a shape from the bead.
And here’s an example of a roughly-finished, but solidly-welded, part with a radical geometry:
How would you make that on a milling machine? Beats us with a stick.
A number of Weld3D’s demo parts appear to be bare-bones de Laval rocket nozzles. Makes sense, in Huntsville. Post-manufacture machining can bring the surface finish into tolerances. This part is a nozzle, machined on the outside. (Other pictures show that it is still rough on the inside).
We, of course, wish both these startups all success, and we think they each show a dimension of the shape of the wave of the future. Weld3D shows that two guys in a garage, standing on the shoulders of academic experimentation, can make something new that has not been made or even imagined before. And Aurora Labs shows that there’s a lot of money out there seeking startups in this field.
We leave the utility of these technologies for firearms development to the reader’s imagination.
Entirely New Technologies: SIS, ?, and Multi-Jet Fusion
So, with so many smart minds working on the problem of building up things in three dimensions, there are more developments than you can easily keep up with. Liebert Publications publishes a journal called 3-D Printing and Additive Manufacturing, edited by 3-D expert Hod Lipson, PhD (professor at Cornell’s Sibley School of Mechanical and Aeronautical Engineering). You must register for ongoing access, but the individual articles linked here should be accessible for about 3 weeks.
New Tech 1: Selective Inhibition Sintering
Selective Inhibition Sintering is a new approach to laser sintering that offers potential for what its inventors call “consumer metal additive manufacturing”. Here’s the paper from 3DP v. 1 No. 3. In this process, rather than apply a sintering enabler (the laser) to the part of a bed of raw powder intended to be sintered, this process applies a sintering inhibitor outlining the perimeter of the intended part. This requires a different slicing algorithm than traditional 3D slicers. (Disregard figure numbers, they’re from the paper).
Then, the whole metal unit is sintered, but the inhibitor ensures that the part can be broken out of the extraneous material (this obviously does impose a recycling burden, but the much lower cost of a sintering furnace versus an industrial sintering laser produces enormous overall savings).
Using a bronze alloy material, the experimenters, Torabi, Petros and Borshnevis from the Center for Rapid Automated Fabrication Technologies (CRAFT) laboratories2 at the University of Southern California, successfully produced parts, including a crescent wrench and an impossible-by-subtractive-methods Möbius Strip. That was the good news:
[A] consumer metal AM machine was prototyped and its capabilities were demonstrated in the successful fabrication of metallic parts. The SIS-metal process has proven adaptable for use in a consumer-level machine by way of an inkjet printhead.
So, proof of concept is successful. Now for the bad news: the .stl files need editing, the software and hardware remains prototypic, experimental, and problematic, and so far, dimensional tolerance is so-so and surface finish bad. And there may or may not be shrinkage problems: too early to tell.
While the proof of concept for a high- resolution and affordable metal alloy 3D printer has been established, there is much room for improvement. Software and hardware upgrades are necessary to improve the robustness of the process. In addition, part strength and porosity have not been characterized for the finished bronze parts. Shrinkage and surface quality of parts may be improved upon as well. It is currently unknown if the intradirectional shrinkage percentage is linear with respect to part length in a given direction. More research will be conducted on variation in interdirectional shrinkage (X vs. Y vs. Z) as well. Lastly, overpenetration of liquid inhibitor results in surface defects in up- facing surfaces of the sample parts. A fine-tuning of inhibitor deposition is planned to avoid these defects.
New Tech2: Laser Solid Forming
From the same edition of 3D Printing, we learn of this highly-developed Chinese technique. Starting in 1979, the United Technologies Research Center of the State of the Northwestern Polytechnical University in Xian, China, has been working to develop an energy-beam material-deposition technology for prototyping, manufacturing, and repair. Their objective, which they claim to have partially reached, was to make an additive manufacturing technology that can produce Titanium alloy, steel alloys, and superalloy parts with mechanical properties equal to or superior to wrought and even forged alloys. It is unclear whether what they describe is identical to extant western methods like SLS or DMLS, or is entirely new Chinese know-how.
This is obviously not going to be a desktop technology, but the Chinese have employed it with imagination, as in this hybrid additive/cast engine casing using two separate Inconel alloys:
The additive manufacturing characteristics make it easy to combine LSF technology with the conventional processing technology, such as casting, forging, and machining. Figure 10 shows In718/In961 dual-alloy casing of an aero engine by hybrid manufacturing with LSF and casting. The main body of the In961 alloy of the casing is made by casting, and the complex parts of the In718 alloy in the casing are built by LSF.
They have also put this technology to work doing high-value, high-precision repairs on Inconel and titanium parts. They’re not perfect yet, but:
For repairing by LSF, the mechanical properties of the repaired zone can be matched with the main body to achieve high-performance repairing through the composition and microstructure control of the repaired zone with a synchronous material feeding technique.
Prediction: sometime in the 21st Century it will be practical for an arsenal, or even a gunsmith or restoration shop, to fix pitted barrels and other steel parts as good as new. You read it here first.
The Chinese paper is both delightful and frustrating: delightful because it describes in detail what Weidong Huang and Xin Lin and their colleagues have done, but frustrating in that there is little detail on how they do it. That was, however, beyond the scope of their article, and the answers may line in the many references Huang and Lin cite.
New Tech 3: A Nonmetallic Technology to Watch
HP is planning to introduce a new plastics printing technology, Multi-Jet Fusion, which uses a bed of materials, much like laser sintering, but then applies chemical fusing and “detailing” (which seems to mean “inhibiting”) agents to define the shape of the printed part, and then fuses the part with energy, generally laser-delivered.
These printers are years from the market, but they offer two very interesting potential capabilities: very high precision and parts with variable properties in different parts of the part. (Now, any machinist who ever heat-treated one end of a tool is thinking, “I do that all the time,” which is true). One wonders if the unfused material is as easily recovered in this process as it is in laser sintering. Most of the hype around HP MJF seems to focus on its ability to make parts of multiple colors, but we think multiple hardnesses and flexibilities are the real long-term winner of this technology. Time will tell.
1. The Direct Metal Laser Sintering used by Solid Concepts to print guns of stainless steel and Inconel is not a Stratasys technology; DMLS was developed by EOS of Munich, Germany, and Stratasys’s own technology is restricted to plastics. Indeed, Stratasys may have acquired Solid Concepts and Harvest Technologies not only as going businesses, but also to get eyes on competitors’ technologies that those two service bureaux own and use.
2. The URL for the CRAFT lab in the paper itself is wrong (yes,the guy’s own link to his own lab 404s). The correct link is this: http://www.craft-usc.com. CRAFT has been working on SIS for at least 10 years, and has demonstrating printing of ceramics with this technology already.