by makeme

Archive for February, 2012|Monthly archive page

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.