by makeme

3D Printing and Open Source Appropriate Technology

In Uncategorized on 05, Feb, 2012 at 09:39

The Open Source community already has a thick streak of sharing built into its DNA. But just straight “sharing” really only works for one’s technological peer group. Just because something is published for free doesn’t mean everyone in the world has the tools and/or skills to access or utilize it.

Open Source Appropriate Technology (OSAT) is attempting to close that gap. Appropriate Technology on its own might best be characterized as designs for systems that do not depend on unsustainable, capital-intensive technology from industrialized sources. There are several different ways to achieve that goal, some of them shaped more by ideology than by economics. The focus on how Open Source can deliver Appropriate Technology is a new one that has only been made possible by the dramatic spread of internet-connected devices around the world.

A paper titled 3-D Printing of Open Source Appropriate Technologies for Self-Directed Sustainable Development, written by J. M. Pearce, C. Morris Blair, K. J. Laciak, R. Andrews & A. Nosrat and I. Zelenika-Zovko, and published in The Journal of Sustainable Development, “…critically examines how open source 3-D printers, such as the RepRap and Fab@home, enable the use of designs in the public domain to fabricate open source appropriate technology (OSAT), which are easily and economically made from readily available resources by local communities to meet their needs.

Their focus isn’t on 3D printing so much as on OSAT and how 3D printing (in whatever form) can deliver it. They propose four categories of OSAT

1) Things that can be printed on existing printers. This category might include facial prosthetics (Feng & friends, also in this paper by (Mueller & friends ) and limb prosthetics. Also water system parts, specifically taps (Meah & friends). Tools and/or customization of existing tools, like wrenches, clamps, pulleys and gears.

2) Things that can be printed on existing printers, but would require the introduction of at least one new material. This would probably be accomplished by casting the plastic part in metal so it can resist higher temperatures and stresses. This category could be occupied by grills, circuit boards, and anything that requires a small metal part that can be cast rather than forged.

3) Things that can be printed with proven materials, but only if the printer is bigger. These could be solar dehydrators, solar stills, and solar pasteurizers. An important point is that large objects won’t be practical, even with a larger printer, until the print speed increases dramatically.

4) Things that require both larger printers and unproven print materials. Perhaps a large locking pressure cooker for desalination (complicated locking design), farm equipment, industrial equipment, and bulky medical equipment.

Their ideal requirements for a 3D printing process:

  • inexpensive (would probably follow from some of the other requirements)
  • self-replicating from locally available materials
  • printing feedstock made out of locally available materials
  • free/open access to designs and design software
  • fast print speeds that don’t compromise accuracy
  • uses locally available energy and little of it
  • free/open technical support
  • no (or very little) pollution

This analysis leads them to the rather obvious conclusion that OSAT requires several technological advances from the 3D printing world:

  • 3D printers need to use local feedstocks. They suggest using bio-polymers or recycled plastic waste. Additionally, they suggest a printer that can print directly with (recycled) metal. They also point out the need for the printer to adapt to and use whatever feedstocks are most economical in a particular location at a particular time.
  • They need to print bigger and faster. Ironically, it’s very western of them to want “more, now” which made me chuckle a bit. I guess Canada isn’t entirely free of America’s influence.
  • The finished product needs to have a wider selection of materials. They said it better than I could, “As open source 3-D printing is largely relegated to the hacking community, the full weight of the materials science and engineering community has [not] yet been applied.”
  • The whole thing needs to be solar powered. The sort of people targeted by OSAT are the sort of people who don’t have access to electricity, either because their supply is unreliable or because it’s nonexistent. The power draw of a small computer and a (current) RepRap is well within the Wattage that existing photovoltaic systems can provide. Although, this sort of undermines the point because it strongly implies that the whole thing could be powered by solar right now; all they need is someone to actually go to Africa with a RepRap.

They suggest that a key enabler for solving these problems is collaborative design (Buitenhuis & friends). Additionally, they point out that 3D printing needs some kind of test-based quality control. They would like to see standardized results detailing print accuracy, electricity and feedstock consumed, print time, quality required of feedstocks, yield stress, elastic limit/modulus, Poisson’s ratio, hardness, etc.

 

3D Printers You Might Not Have Heard About

In Uncategorized on 07, Dec, 2011 at 22:23

The Felix 1.0 can be found at FelixPrinters.com for about $1100. Designed by Guillaume Feliksdal because he has experience in mechatronics and he thought RepRaps took too long to put together and calibrate. The kit is mostly aluminum t-slot extrusions. It does not seem to be open source, but it is reportedly quick to assemble and calibrate, taking only 2-6 hours to go from zero-to-printing.

“…I love…to realize innovative technical ideas. The printer could also be useful for making my future inventions.” – Guillaume Feliksdal

The Orca 0.30, designed by Gubbels Engineering, can be found at Mendel-Parts.com. The kit is pretty much entirely steel rod and (anodized!) aluminum sheets, is about $800, and seems to be intended to be open source when the design is finalized.

The Mosaic, designed by Rick Pollack, can be found at MakerGear.com. The kit is mostly laser-cut plywood with pre-assembled precision linear guides, is about $1000, and doesn’t appear to be open source.

The Printrbot can be found at Printrbot.com. Designed by Brook Drumm because he figured people needed a printer that was a lot simpler and easier. The kit is about the most minimal combination of ABS and steel rod imaginable, is listed as $500 on the kickstarter page, and a lot of noise has been made about making it open source when the design is finalized.

Printrbot-Mystery-Print from Printr Bot on Vimeo.

The Prusa Air is Mecano’s redesign of the Prusa Mendel. It replaces a lot of the metal and plastic parts with flat sheet. Here it is on Thingiverse.com and the RepRap wiki. He says that the design evolved out of an attempt to make the Prusa more attractive and intuitive enough that someone could put it together after glancing at a picture. He has a version 2.0 on the way.

“Eventually I would like to see, apart from improvements in 3D printers, laser cutting open hardware, open hardware lathes, open hardware phones, etc” – Mecano

The Rook Printer by Jolijar can be found on Thingiverse and at Jolijar’s blog. He’s replaced the vast majority of the RepRap frame with t-slot aluminum and has redesigned the printed parts accordingly.

The Solidoodle 3D Printer, designed by Sam Cervantes, can be found at Solidoodle.com. This is a somewhat unusual design. Most of the functional parts are laser-cut wood, but the whole thing is enclosed in a steel frame that protects the whole printer. It only comes fully assembled for $700. The design doesn’t seem to be open source, but they do have a Facebook page. So you’ll have to make due.

The 3D Micro Printer is a stereolithography system that’s about the size of a large book and is only about $1600. It is the result of collaboration between teams led by professor Jürgen Stampfl and professor Robert Liska at the Vienna University of Technology. The prototype was developed by Klaus Stadlmann and Markus Hatzenbichler. The real strength of this approach, and the reason the overall machine is so small, is that it can be used to print very precise parts. This first generation prints in layers 50 microns (0.050mm) thick.

The following are even farther off the beaten path because they are CNC mills.

Don’t let that be a reason for ignoring them! Unlike a dedicated 3D printer, a CNC mill can do both additive and subtractive work (3D printers aren’t rigid enough to hold a carving tool in place without wobbling).

The MTM Snap has an exceptionally clever design. It was designed by Jonathan Ward at MIT’s Center for Bits and Atoms and it actually snaps together. Yes, snaps. The entire structure is rigid enough for milling but doesn’t include a single fastener. It is open source.

http://blip.tv/play/AYK2j0IC.html

The White Ant was designed by Patrick Hood-Daniel and can be found at BuildYourCNC.com. Looks like it’s around $1000, but for that you get a machine that’s specifically designed to be either a 3D printer or a CNC mill. It’s a compliment to the book, Printing In Plastic, which takes you through the entire build process. It’s extremely hackable, as the design has been released under the Creative Commons license (free to reproduce) and, while it’s cleaner to CNC mill the wood pieces, the entire thing can be made in a garage with power/hand tools.

“I would like to see a machine that would be able to fabricate using multiple materials in one process…I will be developing an SLS machine kit in the near future.” – Patrick Hood-Daniel

ZEN Toolworks, owned by Xin Chen,  has several variations of a hobby CNC. They also have a very nice wiki for learning about their kits. The CNC mill is about $810 and they have a conversion kit for $80 that makes the build volume more suitable for 3D printing. They don’t sell any extruders and Xin explained that they don’t sell a complete kit (mechanical and electrical) for 3D printing because they figure it’s better to get 3D printing-specific electronics from somewhere else. However, you can pick up the mill itself (just mechanical) for about $450 and get the electronics & extruder from a different vendor. This product is not open source.

The micRo (yes that’s how it’s spelled) is available at micro.lumenlab.com for around $700. You’ll get the CNC mill which you can use for 3D printing if you mount an extruder or syringe. LumenLabs does seem to be working on a high-precision 3D printing addition to turn the micRo into the UNIFAB, but there’s not much information at the moment.

Maybe you prefer your projects a bit more…freeform. If so then check out how many 3D printers/CNC machines there are on Instructables.com.

So there you have it. The 3d printing world is a lot bigger than RepRap and Makerbot! The great thing is that more and more of these new designs are showing up all the time. Pretty soon there will be such a huge selection you’ll be able to find one that exactly suits your requirements. Additionally, the point of this post was little-known 3d printers. If you know of one that I missed please share that information with everyone else.

Professionals Do It On Powder Beds

In Uncategorized on 23, Nov, 2011 at 12:00

There are a lot of approaches to additive manufacturing. Fundamentally, however, they all break down into a few categories:

  • points
  • lines
  • planes

Planes means using sheets of material. This approach is usually more of a combination of additive and subtractive, since the excess sheet has to be trimmed away. Lines means using long thin noodles (floppy or rigid) to build up the part. Points means using powder, either laid down in a bed or shot out of a nozzle.

I’ve been trying to come up with a way to take Fused Filament Fabrication (FFF, AKA: the copyright free version of FDM) to the next level by removing the need for a support structure. If you can free up the extruder nozzle to move in more dimensions relative to the build surface you can print “overhangs” right onto the part instead of printing them onto thin air.

3d print FFF without overhangs

This approach would definitely allow an extruder-style printer to print nearly-arbitrary shapes faster and with less waste. However, it would not allow printing of truly arbitrary shapes. The easiest example of this limitation is the spiral. It doesn’t matter where you start from, an extruder-style printer is going to have to use support material to print a spiral.

cant print a spiral

Ultimately, if you want to print arbitrary shapes, you’re going to have to hold everything in place until you can get the entire print finished so that every little bit is attached to every other little bit. Either you use support material, or there are some things you just don’t print. That being the case, might as well embrace support material, and nothing is supportier than a powder bed.

CandyFab is a good open-source example. Here’s a great overview of the process by How It’s Made (my favorite show evaaar!)

There is a sort of natural difference here between hobby 3D printers and professional 3D printers. Powder beds allow for truly arbitrary shapes, but they require a lot more of the printer and the environment the printer is in. I think this means that hobby 3D printers will be limited to nearly-arbitrary shapes. Maybe in a decade there will be pro-sumer printers next to the drill presses at home improvement stores that will use powder beds. It’s at least a possibility.

The result of my investigation, and the point of this post, is that I don’t think the open-source hardware movement is going to drive the development of powder bed printers. I think those are going to be left for the professionals.

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