Thursday, May 29, 2008

RepRap: Big step up in print quality!

This posting on the RepRap blog shows the massive progress these guys have made recently in their printing quality. The progression is clearly visible in this photo of some door handles. The most recent incarnation is the work of a guy known as "Nophead", with his own blog describing his work. His machine uses a RepRap extruder on a purchased CNC table rather than the RepRap 3D platform, which made me think that the RepRap platform must be the reason for the less-than-commercial-grade print quality. I asked him about this in a comment, and he replied that the improvements were:
  • his extruder has a shaft encoder to control the speed precisely
  • he has temperature control to +/- 3C
  • he doesn't have any comms delays (I don't know the architecture well enough to know exactly what he means here)
  • he runs his head faster so as to stretch the filament down to 0.5mm.
  • careful choice of printing material
To conclude, he says "All these things can be sorted out on Darwin [the current RepRap prototype] so I expect its prints to be this good in a month or two." That's a very cool thing. It's wonderful to see such progress.

Within just a year or two, RepRap will be much further along in terms of both quality and ease of use, and it will be affordable for small clubs in high schools and colleges all over the world, and large numbers of individual hobbyists. By then it will probably print multiple materials including conductive ones, so you'll be able to embed circuitry in a widget. Today one of the big killer apps for 3D printers is little action figures based on avatars from Second Life and similar games, but when 3D printers really are ubiquitous, people will move on to far more interesting apps that I can hardly imagine.

Let me not forget this very nice list of a lot of different commercial and hobbyist 3D printers.

Still waiting for my CNC mill platform, the eBay fellow has been getting a huge volume of business and his shop is a bit swamped. I've been getting a bit more organized with the electronics, including resuscitating an old FX2 board design, and I've ordered some stepper motor driver parts that should arrive soon.

Wednesday, May 07, 2008

Affordable CNC gadgets

CNC has existed as a hobbyist pursuit much longer than 3D printers have been. I finally broke down and purchased one of these on eBay. It will take a couple weeks to arrive, and the one I got did not include stepper motors, couplers, or motor drive electronics. Those are things I'd enjoy doing myself anyway, so no problem.

I like this project which is along similar lines.

For my own gadget, I need to order stepper motors, think about couplers, and start planning how the electronics will go together. I'm thinking about being lazy and using the parallel port.

I got to see a real RepRap up close!

This evening I went to a presentation and demonstration of a real live RepRap by Bruce Wattendorf and his son. It was very cool to meet somebody who's built a real one and is totally up to speed on every aspect of the project. I asked some questions about the long-term future of the RepRap project.
  • Can they get much better spatial resolution without compromising the social goal of serving the developing world? Yes: better spatial resolutions can be gotten with finer nozzles, which would print slower. You could build a duel-nozzle gadget with a wide nozzle for fast clumsy printing, and a narrow fine nozzle for slow elegant finishing.
  • Will they bump into patent problems as they move toward the state of the art currently occupied by commercial 3D printers? A number of patents will expire in about three years and the RepRap guys will then be much freer in this area.
He wrapped up his presentation by showing the nanofactory video, "Productive Nanosystems: from Molecules to Superproducts". I came to 3D printers from an interest in nanotech, and he came to nanotech from working on 3D printers. It was gratifying to see that the similarity is clear to people on the other side of the fence.

It was a heck of a lot of fun. I took some pictures. Bruce also has many more pictures on his blog. Interestingly, the parts that are normally plastic in a RepRap are made of wood in Bruce's machine, and he's in the process of printing a set of plastic parts.

Bruce's talk was sponsored by a group called DC401, a bunch of Rhode Island folks who enjoy going to DefCon. They are working with a woman in real estate to arrange a lab space in a building in downtown Providence where they can do electronic and mechanical tinkering. It was fascinating to hear her talk about how she's making it all work by using the other floors for businesses and residential space. This reminds me a lot of MITERS, and it warms my heart.

Tuesday, May 06, 2008

More developments in cancer treatment

Here are some more new cancer therapies under development. Many of these involve some flavor of nanoparticle (a fancy word for a molecule), and a few involve nanomachines (a molecule that does something more interesting than just sitting there).
  • -- The new nanoengineered system, designed by physician and researcher James Baker and his colleagues at the University of Michigan, contains gold nanoparticles with branching polymers called dendrimers that sprout off the nanoparticle's surface. The particles could be used to launch a multiprong attack against tumors. The dendrimer arms can carry a number of different molecules, including molecules that target cancer cells, fluorescent imaging agents, and drugs that slow down or kill the cells. Once enough of the nanoparticles have gathered inside cancer cells, researchers could kill the tumors by using lasers or infrared light to heat up the gold nestled inside the dendrimers.
  •,319,p1.html -- A single treatment of drug-bearing nanoparticles effectively destroys prostate cancer tumors in mice ...the researchers mix together a prostate cancer drug (docetaxel) and polymers that are already FDA-approved... The polymer formed spheres with the drugs trapped within. The researchers then chemically attach pieces of RNA, called aptamers, to the surface of the spheres. The RNA folds into shapes that fit into complementary structures on the surface of prostate-cancer cells... [In placebo groups] almost all the mice died during the experiment. In contrast, all of the mice injected with the targeted nanoparticles survived, and in most cases (five out of seven) the tumors disappeared.
  • -- We present experimental data that demonstrate the potential of synthetic crown ether modified peptide nanostructures to act as selective and efficient chemotherapeutic agents that operate by attacking and destroying cell membranes.
  • -- Researchers from the Nano Machine Center at the California NanoSystems Institute at UCLA have developed a novel type of nanomachine that can capture and store anticancer drugs inside tiny pores and release them into cancer cells in response to light... the device is the first light-powered nanomachine that operates inside a living cell... [reported on] March 31 in the online edition of the nanoscience journal Small.
  • -- The nanoparticles are extremely tiny beads of an inert, oily compound that can be coated with a wide variety of active substances. In an article published online in The FASEB Journal, the researchers describe a significant reduction of tumor growth in rabbits that were treated with nanoparticles coated with a fungal toxin called fumagillin. Human clinical trials have shown that fumagillin can be an effective cancer treatment in combination with other anticancer drugs... the nanoparticles' surfaces held molecules designed to stick to proteins found primarily on the cells of growing blood vessels. So the nanoparticles latched on to sites of blood vessel proliferation and released their fumagillin load into blood vessel cells. Fumagillin blocks multiplication of blood vessel cells, so it inhibited tumors from expanding their blood supply and slowed their growth.
  • -- ...Regulators and drug developers are concerned that these delivery systems may prove difficult to manufacture on a consistent basis... A new study from James Baker, Jr., M.D., PI, Cancer Nanotechnology Platform Partnership at the University of Michigan, and colleagues provides data showing that such concerns can be overcome... the investigators present the results of studies designed to show that they could achieve consistent and specific targeting and cell-killing activity across multiple manufacturing batches of a dendrimer-based therapeutic agent.
  • -- A team of investigators has designed a nanoscale, polymeric drug delivery vehicle that when loaded with a widely used anticancer agent cures colon cancer in mice with a single dose... To create their drug delivery vehicle, the investigators used a highly branched polymer, known as a dendrimer, that naturally forms nanoparticles with myriad sites for drug loading. In this particular case, the researchers created what they call a bow-tie polyester dendrimer, whose molecular structure somewhat resembles a bow-tie with two discrete halves... On one half of the dendrimer, the researchers attached a second polymer, poly(ethylene glycol) (PEG), in order to make the dendrimer water soluble... Next, the investigators attached the anticancer drug doxorubicin to the other half of the dendrimer using a chemical linkage designed to break when exposed to acidic conditions. Not coincidentally, the inside of tumor cells is acidic, while the bloodstream has a neutral pH. Results presented in this paper show that the resulting drug-dendrimer formulation releases virtually all of its drug within 48 hours in acidic conditions but less than 10 percent of its payload at neutral pH.
  • -- A new type of cancer detector... the simple and inexpensive system, which can be built from off-the-shelf components, can rapidly detect the presence of cancer biomarkers – telltale proteins in body fluids that can signal the presence of malignant tumors – at very low levels... “With this technology, a future scenario might be that you go to the doctor every year for an annual checkup; he draws about 10 cc’s of your blood and runs it through our machine,” said Soman. “The machine is equipped to detect the biomarkers for all the common types of cancer. Half an hour later it produces a list of the biomarkers that it has found. And then either a software program or the physician examines this list to determine whether you have any cancers that need treating.”
  • -- There is a growing recognition among cancer researchers that the most accurate methods for detecting early-stage cancer will require the development of sensitive assays that can identify simultaneously multiple biomarkers associated with malignant cells. Now, using sets of nanoparticles designed to aggregate in response to finding more cancer biomarkers, a team of researchers funded by the Alliance for Nanotechnology in Cancer has developed a multiplexed analytical system that could detect cancer using standard magnetic resonance imaging (MRI).
  • -- A survey of several different developments, but not much deep discussion of any of them. More of a businessman's-eye view of things, not too surprising for Forbes.