When I said hollow I meant entirely, like a hollow sphere. And when I was talking about overhangs I meant he non-powder method without support.
The powder method has a weakness in a literal sense of the unfired part being too fragile, shapways say to consider if it could be made with wet sand. On Tue, Feb 26, 2013 at 5:49 PM, Paul Breed <p...@rasdoc.com> wrote: > 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 <berry.joh...@gmail.com>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 <jedrothw...@gmail.com>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 >>>> >>>> >>> >> >
