Octet Truss Cube: Printability Update

This little octet truss example cube moved from "First to Try" to "Successfully Printed" on my Shapeways store. They estimate a greater than 80% success rate on the print (thanks to whoever ordered the part!).

I knew it could be printed since I had previously printed versions of this design, but Shapeways updated their print-ability guidelines since then. Nice to see it still works!

Fun with Machines that Bend

I really like his 3-D printed titanium part at about the 8 minute mark, and the chainsaw clutch at minute 10 is pretty neat too.


The eight "P's" of compliant mechanisms:

1. Part count: reduced parts count with bending parts instead of hinges and springs
2. Production processes: lower price through processes like injection molding
3. Price: lower because of reduced parts count and affordable processes with reduced assembly
4. Precise motion: no backlash (yea!),
5. Performance: no need for lubricants, reduced wear
6. Proportions: can be made at small scale with photolithography
7. Portable: lightweight
8. Predictable: the operation of the mechanism can be well-known and reliable

InverseCSG recovers CAD from model

The MIT Computational Fabrication Group has a page up with the abstract and links to the paper and video. The InverseCSG folks took a program synthesis approach to enable them to generate CAD boolean operation "programs" from the 3D model "specification."

OpenLSTO: New Open Source Topology Optimization Code

Optimized 3D Cantilever from OpenLSTO Tutorial

I was excited to see this short mention of a new open source topology optimization code in the Aerospace America Year in Review.

In July, University of California, San Diego published open-source level set topology optimization software. This new software routinely runs 10 million element models by adapting and tailoring the level set method, making design for additive manufacturing immediately accessible.
New computing tools, international collaboration spell design progress

The software site for UC San Diego's Multiscale, Multiphysics optimization lab has the basic license information, and links to documentation and downloads. The source code is up on github as well.

Monoprice Mini Delta 3D Printer

I recently bought my first personal 3D printer. I have been involved in DIY and hobbyist 3D printing for many years through the Dayton Diode hackerspace I co-founded. This Monoprice Mini Delta is the first printer of my very own. The price point is amazing (less than $160!), and things just work right out of the box. What a hugely different experience than building that first printrbot kit (RIP printrbot). The Printrbot story is actually a piece of the Innovator's Dilemma playing out in this market niche. Printrbot disrupted a higher-cost competitor (Makerbot) who retreated up-market towards higher-end machines, and was then in-turn disrupted by foreign suppliers like Monoprice. This caused Printrbot to reatreat unsuccessfully up-market themselves towards $1000 machines. Who will disrupt Monoprice? I can't wait for my voice controlled, artificially intelligent, $20 printer... In the meantime, this post is about my experience with this little desktop FDM machine you can buy today.

Exciting 3D Print Service Developments

It has never been easier to go from a design in your head to parts in your hand. The barriers to entry are low on the front end. There are all sorts of free and open source drawing, mesh editing, modeling or CAD applications. On the fabrication end of things, services like shapeways, and imaterialise continue to improve their delivery times, material options and prices.

One of the recent developments that deserves some attention is in metal 3D printing. imaterialise has offered parts in DMLS titanium for a while, but they've been pretty pricey. They have now significantly reduced the prices on Ti parts, and are now offering a trial with aluminum. Not to be left out, Shapeways has graduated SLM aluminum from its pilot program.

It's great to see such thriving competition in this space. I'm working on some models specifically for this metal powder-bed fusion technology. What will you print?

Fully Scripted Open Source Topology Optimization

Helical Extruder Gear for Printrbot with Optimized Topology

I've used a couple different methods for stringing together open source tools to do topology optimization, but they have all required some interactive user input. Here are some previous posts demonstrating those manual methods:

• Open Source Topology Optimization for 3D Printing
• Octet Truss for Topology Optimization
• Prusa Mendel RepRap Frame Vertex Topology Optimization Using ToPy
• 3-in Tack Strip Bracket TopOpt

Those approaches are fine if you've got time to fiddle with interactive software, but I wanted to do some parametric studies, so I need an automated approach that would be scalable to lots and lots of optimizations.

3-in Tack Strip Bracket TopOpt

I found a useful bracket on thingiverse for mounting things on a 3-in tack strip. Of course I thought this was a perfect opportunity for a bit of topology optimization. All of the design files and the stl (rendered above) are available on GitHub. The part is also on thingiverse.

Here's a video showing the progress of the optimization:


Rendered with a wave texture in Cycles to give the layered look it would have from an FDM machine, not quite right, but pretty close:

SpaceX SuperDraco Made with DMLS

SpaceX completes Super Draco Qual

From the press release:

The SuperDraco engine chamber is manufactured using state-of-the-art direct metal laser sintering (DMLS), otherwise known as 3D printing. The chamber is regeneratively cooled and printed in Inconel, a high-performance superalloy that offers both high strength and toughness for increased reliability.

“Through 3D printing, robust and high-performing engine parts can be created at a fraction of the cost and time of traditional manufacturing methods,” said Elon Musk, Chief Designer and CEO. “SpaceX is pushing the boundaries of what additive manufacturing can do in the 21st century, ultimately making our vehicles more efficient, reliable and robust than ever before.”

GE Jet Engine Bracket Challenge Winners

Topologically Optimized Bracket by KMWE + TU Delft

The winners for the GrabCAD GE Bracket Design challenge have been manufactured and tested. See all the pictures here. The team I mentioned previously that was using topology optimization went ahead and manufactured their bracket themselves. What a great demonstration of metal additive manufacturing (3d printing) and topology optimization. I hope the GrabCAD folks get the promised detailed feedback for all the entries up soon.

Free (not Libre) TopOpt App

This little app from the TopOpt research group at the Technical University of Denmark is lots of fun to play with. Versions available:

• iOS AppStore
  
• Android Google Play
  
• On the web
  
• pre-compiled binaries for Linux
  

You can move around boundary conditions and forces to see what 2-D arrangement of material is the stiffest. There is also an option to export the geometry to an stl file for 3-D printing.

I couldn't find links to any source for this implementation, but it is based on the methods in the 99- and 88-line codes I've written about previously.

GE Jet Engine Bracket Challenge: Phase I Winners

I wrote previously about some neat entries in the GE Engine Bracket Challenge on GrabCAD that used topology optimization. As reported by GE, they have picked their winners from Phase I. Phase I consisted of simulating the submitted parts in several different load cases and ranking them by how much weight the designer was able to shave off.

Located around the world, finalists include:

• Ármin Fendrik, based in Hungary, is a third-year university student and this entry is among his first 3D printing designs.
• Thomas Johansson, Ph.D, based in Sweden, is a consultant for a Swedish hyper-car manufacturer and is a champion snowmobile drag racer.
• Nic Adams, based in Australia, supported the installation of a pathology lab automation system in a Sydney hospital, which includes a robotic handling system that helps analyze hundreds of test tubes each day.
• M Arie Kurniawan, based in Indonesia, is co-founder of an engineering firm that provides high quality mechanical engineering, design optimization and product design services.
• Sebastien Vavassori, based in the United Kingdom, is a stress engineer for a leading European space manufacturer and service provider.
• Piotr Mikulski, based in Poland, works as a rapid prototyping systems specialist for a Polish-Swiss joint-venture that provides industrial and machining services.
• Andreas Anedda, based in Italy, is a postgraduate university student and holds three patents.
• Alexis Costa is based in France.
• Mandli Peter is based in Hungary.
• Fidel Chirtes is based in Romania.

These winner from Phase I will have their designs "printed" in Titanium and then tested by GE to determine the winners for Phase II.

3-D Printing in DoD: Who's Dragging Their Feet?

I found this article, Why is the Pentagon Dragging Its Feet on 3D Printing, by way of Small Wars Journal. It has some interesting information. The Army is deploying mobile Fab Labs, which seems like a mini MIT FabLab in a shipping container. I think this is a really neat idea. How this can be characterized as feet dragging, I'm not sure. The feet dragging accusation is based on some hand-waving from an article on Disruptive Thinkers, and another article that seems to be worried that there is no Pentagon overlord in charge of an additive manufacturing strategy:

With possible dwindling budgets on the horizon, a clear strategy and cohesive approach is essential to create efficiencies in the area of research and development as well as eliminating duplicative efforts. In order for DoD to take advantage of what is anticipated to be an explosion in the commercial sector within the next ten years, the Department must take an active approach, partnering with the private sector to keep up with this relatively nascent technology and shaping/guiding it towards the desired end state the department has in mind.

One step towards a clear strategy and cohesive approach is for DoD to designate an AM Czar within the Department. They could serve as a single point for all things AM and not the myriad of technical advisory boards that currently exist. This office could then work with policy makers to execute and monitor a strategy which will allow DoD to take full advantage of this technology. Logically, this office would interface directly with the National Additive Manufacturing and Innovation Institute (NAMII) as DoD's representative
3-D Printing Revolution in Military Logistics

I think an "additive manufacturing Czar" sounds like a terrible idea (so I'm sure it will secure funding for some beltway bandits to do a study). I know my recent success with qualifying a particular additive manufacturing process and supplier for use in 3D printing wind tunnel models did not need a Pentagon king-pin to tell me about DoD's strategy for additive manufacturing. Using this technology just made sense as a way to solve my problem: get a complex wind-tunnel model rapidly, and at an affordable cost. I did not receive top-down direction or guidance to use AM, I simply took the initiative to solve my problem. After reading that article I'm left wondering, just how exactly is waiting on direction from the very heights of the bureaucracy supposed to lead to innovation?

ITAR Public Domain: DIYDrones and Defense Distributed

What is public domain for ITAR compliance purposes? Apparently, being available on a NASA website for years and widely available to the public without restriction is insufficient (and frustrating for aero engineers like me!).

This question has raised discussion on the DIYDrones site:

By and large, open-source qualifies as public domain, so the active technology being created free by the Internet and shared by the Internet means it's exempted.
--Chris Anderson, DIYDrones founder
5 steps to cutting costs: Open-source leads to regulatory breaks

Anderson goes in to more detail,

Autopilots are export controlled by the International Traffic in Arms Regulations (ITAR), which is why it's very difficult for US manufacturers to sell abroad without incredibly complicated guarantees about security procedures put in place by the buyer. That doesn't just apply to autopilot hardware; it also covers autopilot software, groundstation code and other technology in digital form such as schematics. And "export" doesn't just mean physically sending boxes abroad, it also covers "export by electronic means" such as over the Internet.

So why haven't we been arrested? We publish autopilot code, schematics and PCB design files here, and nearly half of our user base is outside the US. The answer is the "public domain exclusion" in ITAR. Because we're open source and release everything to the general public, it's no longer subject to export control.

Why haven't we been arrested?

The argument Anderson is making is the same one that Cody Wilson made about his Wiki Weapons project. Wilson took a "belt and suspenders" approach to getting his files into the public domain,

Wilson argues that he’s also legally protected. He says Defense Distributed is excluded from the ITAR regulations under an exemption for non-profit public domain releases of technical files designed to create a safe harbor for research and other public interest activities. That exemption, he says, would require Defense Distributed’s files to be stored in a library or sold in a bookstore. Wilson argues that Internet access at a library should qualify under ITAR’s statutes, and says that Defcad’s files have also been made available for sale in an Austin, Texas bookstore that he declined to name in order to protect the bookstore’s owner from scrutiny.

State Department Demands Takedown Of 3D-Printable Gun Files For Possible Export Control Violations

However we see two very different trajectories in each case. DIYDrones is merrily turning out hardware and software, and publishing it all online, while Defense Distributed recieves take-down letters from the State Department. I can't see in the ITAR definition of public domain how the two situations should recieve different treatment.

§ 120.11
Public domain.
(a) Public domain means information which is published and which is generally accessible or available to the public:
(1) Through sales at newsstands and bookstores;
(2) Through subscriptions which are available without restriction to any individual who desires to obtain or purchase the published information;
(3) Through second class mailing privileges granted by the U.S. Government;
(4) At libraries open to the public or from which the public can obtain documents;
(5) Through patents available at any patent office;
(6) Through unlimited distribution at a conference, meeting, seminar, trade show or exhibition, generally accessible to the public, in the United States;
(7) Through public release (i.e., unlimited distribution) in any form (e.g., not necessarily in published form) after approval by the cognizant U.S. government department or agency (see also § 125.4(b)(13) of this subchapter);
(8) Through fundamental research in science and engineering at accredited institutions of higher learning in the U.S. where the resulting information is ordinarily published and shared broadly in the scientific community. Fundamental research is defined to mean basic and applied research in science and engineering where the resulting information is ordinarily published and shared broadly within the scientific community, as distinguished from research the results of which are restricted for proprietary reasons or specific U.S. Government access and dissemination controls. University research will not be considered fundamental research if:
(i) The University or its researchers accept other restrictions on publication of scientific and technical information resulting from the project or activity, or
(ii) The research is funded by the U.S. Government and specific access and dissemination controls protecting information resulting from the research are applicable.

Previous cases have shown that the restrictions on publishing source code for cryptography violate the First Amendment, why wouldn't restrictions on publishing gcode for 3d printing a drone or a pistol? I think the First Amendment problems around the Defense Distributed case are the real interesting part of this. Wilson's provocations are not really about the 2nd Amendment, the gun is just a clever marketing hook. His focus is on political speech and freedom of the means of production,

PCMag: Are freely available guns the core of your political beliefs or a part of that larger ideology?

Wilson: No, I think it's a very clever way of unpacking the ideology for people. A lot of people get there and stop at the gun. And that's great, like some of the Second Amendment people who are like, "Alright, this is great for guns." No, I think it's more importantly a signal of the future and it helps through just getting at some of these bigger ideas.
Dismantle the State: Q&A with 3D Gun Printer Cody Wilson

In another article,

Wilson said we’re not so much dealing with firearms regulation as “what can be put into the public domain and how.”

“It’s a demonstration of claiming everything in the national security interest,” he said. “They say, ‘well, your useless plastic gun can’t be shared with other people. It’s important to national security.’ In the end, everything will be claimed…”

It seems to be “consistent [with] the total bureaucratization of social space itself,” Wilson continued.
'In the End, Everything will be Claimed'

Probably the biggest reason for the difference in treatment between DIYDrones' Chris Anderson and Defense Distributed's Cody Wilson is that Anderson wanted to build toys for his kids, while Wilson wants to take on the Leviathan. Lesson: be careful what you wish for.

Novel Processes for Advanced Manufacturing: Summary of a Workshop (2013)

Interesting new release from NAP, Novel Processes for Advanced Manufacturing: Summary of a Workshop
Table of Contents

1. Workshop Introduction
2. Additive Manufacturing Session Summary
3. Electromagnetic Field Manipulation of Properties Session Summary
4. Design of Materials
5. Workshop Conclusion

Topology Optimization in GE Jet Engine Bracket Challenge Entry

There is an interesting contest on GrabCAD for designing a lighter weight engine bracket for a GE engine the winner of which GE will produce and test using an additive manufacturing method (maybe DMLS). One of the contestants used PareTO software (methods based on these matlab scripts I linked previously) to design a pretty nice looking bracket.

Update: There are more entries that are using topology optimization.

• KMWE and TU Delft Team Entry. This comment the team makes is interesting: "Since the optimised topology models are in stl we have started to first create a volume model with stp extension so we meet the competition recuirements. This takes a lot of time!" This bottle neck in the work-flow is similar to the problem CFD analysts have with structured grid generation. While many (most) 3D printers will take an stl format file (which is just a triangulate surface), you still really want the normal CAD formats (parametric) for a couple reasons. Usually for the metal printing processes you have to add support material. This is done more easily / accurately with something other than an stl. Also you want to be able to use the part in larger assemblies, and this is likely to go better using a native CAD format.
• GE Jet Engine Bracket v1.5, Topology Optimized Bracket - V4, by Igor Lins e Silva
• GE-jet engine bracket-opti-design-phase 1, by Cheng.Li
• Engine Bracket V2.1, by Igor Lins e Silva
• GE Challenge, by Charlie Pyott. I like this one because he uses a lattice, which reminds me of the octet truss things I was working on previously. Charlie also has a website with other interesting designs.

Octet Truss Improved Time Cost

Previously, I did a quick and dirty scaling study on how long it takes to make a 3D cube of octet truss unit cells in BRLCAD. I posted some questions about the results to the list and got some good recommendations on speeding things up. The approach I used previously was just unioning a big, flat list of primitives. The main recomendation to get speed-up was to introduce a bit of spatial organization in the way the primitives are grouped. I did this by making each unit cell a region, and then making an assembly combination of the unit cells. This is only two levels of hierarchy, so ultimately the scaling is still quadratic. The speed-up is pretty dramatic though. To get the \( N log(N) \) scaling mentioned on the email list would require an octree structure with an adaptive number of subdivision levels. Here's a plot showing the improved time scaling:

Midwest Pilot vs Euro Factories of the Future

I wrote a bit previously about the midwest pilot to increase penetration of high performance computing and simulation into the small and medium enterprises (SMEs) of the US mid-western regional manufacturing supply chain. The similarity to the European 'factories of the future' program jumped out at me as I was reading the recent article in Aerospace America, 'International Beat: Printing your next vehicle'. The article describes the European program:

'Factories of the Future' was set up in 2009, a €1.2-billion public-private partnership between the EC and industry. The research program focuses on the development of new and sustainable technologies highlighted by the Ad-Hoc Industrial Advisory Group to the commission, to help EU manufacturing enterprises--in particular small and medium-sized enterprises--to adapt to global competitive pressures by improving their technological base.

Research areas include new models of production systems (transformable factories, networked factories, learning factories); ICT-based production systems and high-quality manufacturing technologies (including research into increasing autonomous production lines); and sustainable manufacturing tools, methodologies, and processes producing assemblies with complex and novel materials.

With the completion of the EC's seventh framework research program this year, EFFRA has been working to continue the research within the commission's new seven-year research program, Horizon 2020. This will focus on:

• Advanced manufacturing processes.
• Adaptive and smart manufacturing systems
• Digital, virtual, and resource-efficient factories
• Collaborative and mobile enterprises
• Human-centered manufacturing
• Customer-focused manufacturing

Contrast with this from the Council on Competitiveness:

The Council on Competitiveness and selected original equipment manufacturers (OEMs) are developing a Midwestern regional pilot program as a public-private partnership with the U.S. federal government. The pilot program is aimed at improving competiveness and innovation in small- and medium-size enterprises (SMEs) in the U.S. manufacturing supply chain. The ultimate outcome of the pilot program will be a workforce with enhanced technical skills, improved product quality, better customization of products, and job retention and growth.

[...]

The high level goal of this pilot program is to develop and demonstrate a sustainable, scalable and replicable model for accelerating and broadening use of modeling, simulation and analysis (MS&A) in Midwestern SMEs through a public-private partnership (described below). Funding will be provided as seed money for this pilot program, with the expectation that it will demonstrate a path toward long-term sustainability. This is only achievable if (a) the supply chain members can rapidly reach a point where the results produce cost-benefits that allow and incentivize them to continue use of MS&A, either independently or within the continued context of the pilot program, and (b) software vendors can develop a business model that provides easier and more affordable access to software tools for SMEs.

These manufacturing competitiveness initiatives seem to be focused on additive manufacturing or 3D printing right as this technology peaks on Gartner's hype cycle.

3D Printing Tops the Gartner Hype Cycle 2012

Hopefully something useful will be left for us makers, hackers, engineers and small business owners when all the smoke clears and the twittering classes move on to the next big thing. I think this DIY Rocket thing is a clear indication of the heights of unreasonable expectations that we've reached. It is important to sift through the silliness because there's some really good and useful technology to be exploited here.

Coefficient of Thermal Expansion Mismatch: Shapeways Steel-Bronze Composite

	Bronze	420 Steel
CTE (ppm/oF)	10.3	5.7
Conductivity (Btu/(hr oF ft))	15	14.4

The DIYROCKET organization is sponsoring a contest to design a 3-D printed rocket for nano-satellite launch (coverage on Parabolic Arc and Make). Shapeways is one of the competition's sponsors so one of the rules is that you have to use their metal 3-D printing process. The process is not direct to metal, i.e. directly melts the final part material. Their process melts a polymer binder to 'glue' stainless steel powder into the shape of the part, the plastic is then burned out of this green part, and the voids are infused with bronze. The result is a steel-bronze composite with either 30% or 40% (by volume? weight?) bronze content (different parts of the Shapeways site have different numbers).

3D Printing is a Hot Political Topic

3D printing or additive fabrication is a hot topic, and not just to the engineers, fabricators and hobbyists anymore. It seems to be becoming part of the political symbology wrapped up in economic recovery or development. As I commented on the Made in Dayton blog, the National Academies Press recently released a report about Building the Ohio Innovation Economy that includes significant emphasis on additive fabrication, and the President mentioned the National Additive Manufacturing Innovation Institute, located in Youngstown, in his State of the Union address. There is also the Midwest Pilot for connecting High Performance Computing (HPC) resources to small and medium manufacturing concerns. As we saw in this topology optimization post, there is considerable need for scale-able computational approaches to fully realize the promise of additive manufacturing. Closer to home, your Dayton hackerspace is playing with a printrbot.