Pyrex might be a better choice, it's got a lower thermal conductivity, and you can mold it with a blowtorch.by wolfkeeper - General
Yeah, but realistically, many common things contain poisons. Mushrooms? Mushrooms contain hydrazine chemicals. Hydrazine is a horribly poisonous chemical. It's not toxic in the short-haul, but it gives you cancer down the road. Orange juice? Contains methanol. Mehanol is pretty poisonous. PLA is very, very safe; it's just solidified lactic acid. Lactic acid is completely natural. ABS isn'tby wolfkeeper - General
PLA is made of polymerised lactic acid, it should be very, very safe. There will be traces of other chemicals (like zinc is used I believe), but that's very unlikely to be a problem. PLA is actually used for medical implants, it's considered very biocompatible.by wolfkeeper - General
This is similar to the idea I mentioned here: The difference is that I think you should carry multiple dies/nozzles around one horizontal axis cylinder, with internal seals, so that it only extrudes downwards, and you have different sets of nozzles around the circumference. So the hot plastic goes in from the end along the axis and it extrudes downwards, and there's a motor to spin the nozzlesby wolfkeeper - General
Compared with the alternative cost of (say) buying multiple printers to print several times more quickly in parallel?by wolfkeeper - General
I was thinking it might be possible to have multiple dies on a single head. So with a switchable die, you could extrude a single bead, or several beads in parallel with a gap in between, or several beads so they coalesce (basically it's like doing wide tapes.) If it can be done, it could be quite a bit win because the amount of material deposited per second goes up several times, and could be aby wolfkeeper - General
I did some more thinking about this, you could have a single motor axis that sequentially connected to each of the printer axes.The idea is that a 3D printer is not an analogue device it's digital, so you're moving in discrete steps. You can ensure that with various devices to give a clean step each time. So it would output: L R L L R L L L and this would be translated by the mechanical hardwaby wolfkeeper - General
You can design this part cost-reduction manually, just take out spherical (preferably) or cylindrical shapes (failing that) in the interior in a hexagonal format. If you use spheres and the holes overlap slightly, then it's open cell. Avoid removing material very near to stress risers (i.e. holes in the part where you apply force). If the part fails due to buckling, doubling the diameter of the pby wolfkeeper - General
You could fairly easily algorithmically generate a fractal/hierarchical foam with spherical voids if you wanted. That would give you arbitrarily big holes and may help handle the bridging (spheres have some degree of self support, and the end result should be pretty damn rigid. Otherwise it's very difficult to produce structures like that using non 3D printing techniques.by wolfkeeper - General
That's another area of potential improvement, I doubt that a lot of that infill is doing so very much, most of the strength and rigidity of a part is in the skin- making the parts bigger, with more air inside, generally makes them cheaper and stronger.by wolfkeeper - General
I don't think it would be significantly slower. Most of the time the head is moving in one particular direction and extruding. Any extra time only occurs when something changes, but that's going to be only a small fraction of the time.by wolfkeeper - General
I think that it would be a good idea to cost reduce these printers further so as many people can buy them as possible. One thing I wondering was if it was possible to have less axes; so I wondered what the bare minimum is. It looks like you can theoretically make do with a single axis and a plastic mechanism. If that sounds impossible, consider that with a combination lock on a safe a single kby wolfkeeper - General
Over at instructables somebody came up with a neat hack they called 'oogoo': They mixed equal volumes of bath sealant (the type that smells of vinegar, not the newer high tech stuff) and cornstarch (aka cornflour) and found that it goes into a workable putty consistency in 5-10 minutes and sets in about 2 hours (normally that kind of sealant takes weeks, it's something about the humidity in thby wolfkeeper - General
Over at instructables some guy has come up with a cheap, fairly fast, fairly strong 2-part silicone rubber. Basicaliy it's silicone bath sealant mixed with equal volumes of cornstarch (the cornstarch makes it more rigid and supplies the little bit of humidity that sets the bath sealant off very rapidly- normally it takes weeks). I've had a quick play with it and it looks like a good way to crby wolfkeeper - Polymer Working Group