Actually not quite true... I have hollow parts from shapeways... and overhung parts built with DMLS....
To be more precise.... shapeways can not build hollow parts with small passages that can not be emptied while the part is in the green clay intermediate state before sintering. Since both DMLS and the shapaways inkjet process are full powder enclosed, then the over hang capabilities of the two process should be identical. The DMLS has limits on overhangs, either support is added, or the slope has to be limited to something like 45 degrees.... Realize that the finished DMLS part is fully buried in powder so one should be able to build any overhung shape with the possible problem of the powder spreader moving the first layers of a detached overhang around If the part can be built with no detached overhang island, or with a temporary suoport making no detached island then DMLS should be capable of building any shape. On Mon, Feb 25, 2013 at 8:18 PM, John Berry <[email protected]> wrote: > > I previously tried to use the low cost stainless service from shpaeways >> and it had issues with hollow parts and dimensional precision. >> >> > Indeed, their method can't do hollow, and the other method can't do > overhanging pieces. > So you can design something that is impossible to be made by either > method, at least without temporary supports, or the possibility of making a > printer that can use both methods in selective parts of a model. > >> >> On Mon, Feb 25, 2013 at 3:34 PM, Jed Rothwell <[email protected]>wrote: >> >>> I wrote: >>> >>> >>>> It seems unlikely to me that anyone will be able to fabricate a cold >>>> fusion device at home, using 3-D printers or what-have-you. Not for the >>>> next thousand years or so, until those machines evolve into Clarke's >>>> universal replicators. >>>> >>> >>> Maybe 1,000 years is too much, but it will be a long while. >>> >>> There has been a lot of enthusiastic talk about these 3-D printer >>> replicator things. I am all for them! I think they are great. But I think >>> some naive commentators fail to recognize some crucial limitations to >>> today's versions: >>> >>> 1. They use only material. Plastic. They cannot be used to fabricate >>> metal, wood, silicon or nickel. You cannot make a NiCad battery or a cold >>> fusion device with that. >>> >>> 2. Resolution is limited. You could not make a computer chip, even if >>> the devices could lay down silicon and metal. I do not think resolution is >>> fine enough for a cold fusion device. Certainly not nanoparticle devices. >>> >>> Despite these limitations, I expect these things will become useful for >>> making parts in the lab such as the fitting that holds the cathode and >>> anode in place. >>> >>> In the distant future, the capabilities of these machines may gradually >>> expand, until they can lay down any element in any configuration. Such as, >>> for example: a fried egg, the Hope Diamond, a copy of the Mona Lisa correct >>> down to the molecule, or a thermonuclear bomb. That is what Clarke >>> predicted. By the time that happens we can hope that the machines will have >>> so much built-in intelligence, it will refuse to fabricate a thermonuclear >>> bomb. The process will be so complicated that no human will be able to >>> override the build-in protections, or run the machine manually. >>> >>> - Jed >>> >>> >> >
