geert_2

Instead of ABS, maybe you could try PET (ICE) or NGEN (colorFabb), or something similar? I also had PLA parts warping in a hot car, even in moderate spring weather. This starts as soon as the interior reaches ca. 50°C, which can be very soon. But warping did not happen with PET or colorFabb NGEN, at least not in our European summers (and we had an unusually hot one this year). PET and NGEN stick very nicely to the bed, if heated enough to ca. 90°C. Depending on the model, glue may or may not be necessary; I usually print without. Edit: added benefit: PET and NGEN almost don't smell, compared to the horrible ABS fumes.

I have this with PET too (non Ultimaker - ICE). These materials seem to be much stickier and more rubber-like than PLA when molten. PLA is more like yoghurt, PET goes a bit in the direction of chewing gum. For my PET material, printing slow and cool reduces the effect, but does not totally eliminate it.

If you also have a Windows computer, I would suggest DesignSpark Mechanical. This is a limited and free version of the commercial SpaceClaim, and only requires registration. It is provided by the big electronics distributor RS-components. This is very easy to learn, but quite professional, and very well suited for technical designs with geometric shapes (=based on straight lines and circle arcs). Go to Youtube and search for demo's and manuals, to see if it appeals to them. There are a lot of good tutorials. But it only exists for Windows...

As always for fine details: print slow and cool. I don't know how laptop keys look from the underside. But consider creating a different design than the original, to eliminate weaknesses and thin areas. Maybe that is why parts wouldn't print: too thin? You should look in Cura layer view if they are shown any different from Cura normal view. Also, find a material that is tough enough if there are fine parts. PLA is likely to break instead of flexing.

Ik heb dat heel soms in de winter, als het kurkdroog is, bij statische ontladingen. Dan trek ik vonken bij alles wat ik aanraak. Is dat de printer (UM2, non-plus), dan blokkeert die soms. Het kan bij u natuurlijk ook iets anders zijn, vb. een fout in een STL-bestand, defect kaartje, een bug ergens in de software,...

Thanks for the further explanation. I start to see the potential value for a lot of designs. I am not an engineer, so I don't have to design structural things where high loads are a concern. But I do like the concept, and understanding of the philosophy can also improve other (simple) designs which need fixings like screws etc. Where we now would use the traditional chunky designs based on machining and injection moulding limitations. Do you use safety margins in this design concept? Like in traditional engineering where you would use a factor two (or whatever) in strength calculations? Would this concept also work for structural designs, like buildings and bridges, which are made out of lots of smaller parts? I wonder what would come out for bridges like the one below? (Edit: would it result in an organic shape or a "technical" shape?) We have a lot of these here in the port of Antwerp. This is a small one, but some others are more than 70m long, to let huge container ships pass through the docks. They move up in a complex way, to keep the counterweight balanced all the time (=the big block at the back). (Photo from Wikipedia, by user Arafi, CC-BY-SA license) Edit: these bridges not only have to carry the load of trucks, bussen and trains, but also a high wind-load when in the vertical position. PS: the films (GIF-animations) of airplanes above are not mine. They were generously provided by Mr. Google. So all credits go to the original photographer. There are lots of other magnificient turbulence photos: search for: "landing airplane vortex" or similar.

I did a couple of prints in nGen too. My experience is that it is a bit more flexible than PLA, but not stronger. I did print with fans off, at ca. 225°C if I remember well. Layerbonding was good. Color black (plus a few tests in other colors on samples). If it snaps on overload, it snaps very suddenly and unpredictable, and the fracture goes diagonally through all layers: it does not follow layer lines nor printed sausage lines (which indicates that layer bonding is good indeed). So it is better for items that need some flexibility, such as snap-fit clamps. And items that need to survive a car interior in summer. The high-gloss shine is nice for some models, but not for others; it depends on the model. Also, nGen is more difficult to glue: my cyanoacrylate sticks less well than on PLA.

Thanks for this great article. The first thing that came into my mind was that it looked like animal bones. So, after all, nature did a good job... What I am not sure about is the holes and sharp bends near the 4 mounting holes. I think I would rather close these holes and smoothen the sharp bends out a little bit. But that is just my personal feeling. I am from the stone-age, with Flintstone-like designs. Also, we are in a school here, even though a university, so everything needs to be built in solid concrete to survive. It would be good if you could give feedback on how this design behaves in real life tests? In a real airplane, can it handle high side-loads, which might occur due to turbulence or vortices, especially with flaps deployed? And can it withstand heavy vibrations and hammering of the air (I don't know the correct English term)? See the flap-vortices in the landing plane, and the powerfull blasts in the flying plane. And in cars, how would such designs survive crash tests? Or could flexibility or deformability be built-in, to absorb energy and save passenger lives? Your "rocking chair", or kids jumping on the bed, are good examples of unforeseen overloads, which such designs should also be calculated for. Anyway, it seems a promising concept with a lot of potential. Looking out for your next posts in this area. A bit off-topic: concerning weight saving in transport: this is why I do not believe in electrical cars, at least not in the near future. Designers do their very best to save a few 100kg of structural weight to maximise efficiency. And then they add a 1000kg battery... which allows to drive only 200km in real life circumstances (=at high speed, and in start-stop traffic jams, with airco/heating on, with radio on, lights on). And then "refueling" takes a whole day. While with a diesel engined car I can drive 1200km, and refueling takes 3 minutes. The average weight balast of the diesel fuel on such a trip is 25kg (=max weight / 2). Then there is the problem that an electric car consumes as much energy as 100 house-holds. Here in Belgium, the light is already likely to go out this winter, due to shortage of electricity. A diesel has an efficiency of ca. 40%; while an electric car has an efficiency between 5% and 10%, if you include losses in electricity production, transport, batterycharger, battery itself, converter, motor. I sometimes have the impression that electric cars are mainly promoted by people who have no clue about technology and who can't calculate, or people who have a dark agenda... But that is a different topic...

For this sort of special cases, you would best design your own custom supports in your CAD file, I think. What is the purpose of having the numbers on the inside? Even if you are going to print it transparent, and with a dissolvable support material, it will hardly be visible, if at all. And if you print it closed, without openings, there is no way to get the support out.

As it is soft aluminum, can't you just bend it back in shape?

I use DesignSpark Mechanical all the time, but I save the files as STL. My STL-resolution is the default "fine" setting. I never had any problems with that. Maybe you could try that instead of OBJ? Or is there a specific reason why it has to be OBJ? Also in DesignSpark Mechanical, verify that there are no duplicate models sitting on top of each other or partially shifted into each other (=occupying the same space), that walls connected to each other are merged into one object (thus no zero-distance gaps), that there are no zero width surfaces etc... These sort of things could cause problems in any slicer. So you want all parts touching each other merged into one solid object.

If you are going to print stuff like syrup and mayonnaise, I think you should consider developing a nozzle with a shut-off valve? Maybe this could be done with a tiny electromagnet and a lever? Or some sort of tiny rotating ball-valve, or so? On bigger nozzles (ca. 5mm?) this should be possible, I think.

What if you wipe the glass with dilluted PVA first? So it has something to stick to? You could recycle the old supports for this purpose.

Yes, I think it is a good idea to develop your own style. I like this model more than the blind one: it has way more character. Hopefully it comes out well in the printer too.

I knew I had seen this model before. Somewhere, but where, where,...? Yes, indeed, Philippe Faraut, the absolute master in modeling facial expressions in clay. Your copy of the hair and face are really great. But I think it is worth trying the eyes too. ? It is going to be a challenge, because for the tiniest mistake, it would look very weird. But if you can get it right, it would really bring more life in the facial expression. If the details survive printing, of course... It might be a good idea to try modeling eyes only, and print them, and see what comes out? If filament would sag, she would get worms in her eyes... :) If you would let the model lean back 30 degrees on the glass bed, or even more, you would have less problematic overhangs in the face and frontal hair. It would require less support, I think. In the back fine details are less important, and it is easier to clean up. This might be worth a try too? Anyway, looking forward to see the printed results.

Print slow and make sure you have no underextrusion. Also print on the warm side (but not so warm that the material starts to produce too much gasses). So that the extruded sausages can flow well into the corners of existing layers. I would suggest you do little test cubes of 15 x 15 x 15mm, and adjust temperature, speed and flow settings on the fly, to see the effect. But it will never be very good, in my experience. The best I could get with PET (never tried transparent PLA), was some sort of "frosted glass" look. It is good enough to let a light shine through, or a logo embedded in the model. But not for a lens... These are transparent PET (text voids totally enclosed by the model):

I have never printed with nylon, so I am guessing here. Nylon is *very* susceptible to moisture absorption. In injection moulding it is known that in only a few hours, it can absorb so much moisture from the air that production is impossible. So the material has to be dried well, and kept dry during the whole process. Could this also be the problem in your setup? For printing nylon, you would first need to dry the spool in a temperature controlled oven. And then store it in a fully closed box with rotating spool holder, also *while printing*. With only a little opening for the filament to exit. Also, put a big bag of desiccant in that box. There have been talks about several proposed models in this forum, some time ago. Maybe you could find them back? Big food boxes could be a good starting point. Or dedicated machines (I don't remember their names). But as said, this is guessing.

This concept should be integrated in the standard firmware, I think. Maybe best as an option?

I have a bit the feeling that the physicians want it to be like a röntgen: high-density material for bones, medium density for the rubbery stuff in joints (="kraakbeen" in Dutch, but don't know the English term), low density for flesh, and ultralow density for liquids. Is this correct? But that is not how an FDM 3D-print works. At least not with traditional slicers. It just prints a *solid* outer shell, filled with a rectangular grid (usually) to add strength, so the walls don't collapse. Maybe the physicians don't understand this concept, and they are stuck with the grayscale röntgens (or MRI, echo, or whatever scans) in mind? If so, simply print a test model, stop the print halfway so that the grid is visible, and use that as a demo? If this gradual soft to hard approach - or something equivalent - is what they really want, maybe it could be achieved with "inkjet-style" 3D-printers? These spray a liquid, which is then cured by an UV-lamp. The more expensive machines (100.000 euro or more) can mix different liquids in different ratios. So they could mix a flexible liquid and hard liquid (= hard after curing) in ratios from 0 to 100%. Thus by mixing it in various quantities, you could go from very soft to very hard materials in one single model. Of from opaque to transparent. Or from one color to another in fine gradients. But this is not something you can achieve with an FDM 3D-printer. If you have a dual-nozzle printer, and you don't need support material, you could use one nozzle for hard material (or for one color), and the other for somewhat softer material (or for another color). But this is still a sort of "digital" on/off solution, not on a gradient. I am just guessing here, but if this is correct, maybe you first need to clarify the confusion and to educate the other people involved?

Wouldn't the easiest thing be to split each organ or body-part into a different file? And then print each file *separately* with the desired settings that show it best (color, layer height, speed, infill percentage, temperature...)? All of course in the same scale, like Dim3nsioneer said. For example, then you could easily print the heart-file in rose, liver-file in brown, lung-file in pale rose, brains in cream, bones in ivory color, etc... I don't know in how far your medical software allows such splitting off of parts?

If the automatic supports are not suitable, you could design your own. Copy the bottom layer and move it down a little bit, and turn it into a thin plate sitting just below the bottom surface. This will support the bottom layer. And then build a sort of tree-shape scaffold from that plate towards the floor. If your printer has support material (UM3; S5), then you can make the supports in the same as the rest (PLA?), and only make a thin separation layer between support scaffold and real model in PVA. Thus a combination of these ideas:

I do print "half on the roll": I manually unwind a bit of filament, and then wind it up in the opposite direction around a skater wheel (7cm diameter). And then I let it sitting on the roll, now very loose. My print jobs rarely take more than 3 hours, which at 1m/h requires only 3m of filament to unwind and straighten. I do this while the printer is warming up and I am waiting anyway. This has two effects: (1) it straightens the filament and gives it the same bending radius as the bowden tube, ca. 30 to 50cm. So resistance in the bowden tube and nozzle is almost zero. And (2) it completely removes the anti-unwind resistance of the spool, which would otherwise act as a very strong spring that resists unwindind. I also have replaced the spool holder with a frictionless holder with bearings, but I am not sure how much effect this has. I just disliked the jerky movements and sound of the original too much. My UM2 (non-plus) were sensitive to variations in resistance in the feeding traject. I am not trying to convert you :) , but for me this just works: while not perfect, it is good enough for our prototypes. The benefit is that I don't have left over ends of filament for each model. But of course this is method would not work for long prints that take days, or for unattended printing. See this photo where the filament is being bent in the opposite direction around the blue-green skater wheel. A couple of meters are already done and now sitting *very* loose around the spool. The yellow sliding clamp on the edge of the spool is to prevent the filament from falling off sideways. And to prevent it from "auto-unwinding" while I am straightening it.

Concerning this testprint: undersides of overhangs are printed half in the air, so they partially sag or fall down. You can not totally avoid this without support. Printing cooler and slower, and using thicker layers, will somewhat reduce the effect, but not eliminate it. But thicker layers reduce details. I agree with cloakfind that this test print may not be representative for the real print. Optimal print settings often depend on the actual model. Test prints like these are very good to find the limitations of the printer, and to try the effect of different settings (fast/slow, hot/cool). You should do them to gain better understanding of the printing process and of all variables that play a role. And then, based on this understanding, select the best parameters for the real print. If you are still unsure, try this: cut out the most critical parts of the model in your 3D-editor (such as overhangs and fine details), and save them into a new model. And then only print these difficult parts with different settings to try which works best. In thisway you don't waste too much time and material. Or design your own test model that exactly mimics the critical parts in the real model. Make sure layer printing time (and thus layer cooling time) is similar to that of the real model, this has an effect on quality for small models.

Yes, that was my first reaction too... :-) @kmanstudios: out of curiosity, how long did this take you? Hours, days, weeks?

If this is printed with multiple models at once, or with priming tower or so, it could be that the nozzle leaks while traveling through the air, and then deposits that blob onto the model when arriving at the edge? If this is the case, printing slower and cooler should reduce the effect (=less pressure in the nozzle, and filament is less liquid), but it is hard to eliminate totally. If this model is printed alone, without the nozzle traveling elsewhere, the cause must be something else. Maybe settings? But I am not using the latest Cura version, so I can't say anything on that.