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geert_2

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Everything posted by geert_2

  1. This fascinating organic modeling style now slowly seems to become more mainstream. In a recent robot wars series (Battle Bots 2019, USA) there was a robot Quantum in this style (at left, after it won and threw the other bot out of the arena). Its beak can crush with several tons of force. This is a low-resolution screendump, but you can still see the beauty. These fighter robots are often brilliant pieces of engineering.
  2. Yes, you should start moulding on a printed model or on a testpiece anyway, until you have the procedure in your fingers. Don't experiment on sensitive persons. The application of liquid silicone itself on the hand would probably cause no problems, it is just a thick liquid. But the removal of the cured silicone might: you would have to pull and slide that cured silicone off, or cut it off by going under it with scissors. Both will require some force and shear action: in a normal person this is no problem, but on a very sensitive or weak skin it could do mechanical damage. I would suggest you make a silicone impression of one of your fingers: fill a tiny cup with fast curing liquid silicone, put your finger in it, let it cure, and then try to slide it off. This will give you a good subjective feel of it. If you do the moulding on a 3D-printed plastic model, you can cut the silicone in two pieces with a sharp knife (scalpel), or with fine scissors. But I still don't get the purpose of printing a PLA glove? PLA is very hard, and due to the layer lines, and it being biodegradable (=eaten up and broken down by bacteria), bacteria can get a good grab onto it. This might cause health risks. Also, you can't desinfect PLA-prints very well: the desinfectant may not get into the tiny openings. And PLA softens from 55...60°C on, and melts from about 80°C. (I heard from doctors that sometimes PLA supports are used internally in the body during surgery, when putting bones back together, because they gradually dissolve and get replaced by the own body cells.) You might consider moulding the whole glove from silicone: start with soft and comfortable inner layers, where they will touch the skin. Then gradually add layers of stiffer silicone on the outside. If more stability is needed, you could add stiffeners/thickeners into the outer layers of the silicone, which would make it stiff like a car tire. Or add a hard outer shell on top of the soft silicone. Then you have both the comfort of the soft inner layers, and the stability of the hard outer layers. The biggest advantages of silicone are: it can be from skin-soft rubber up to stiff rubber (depending on version), it is chemically almost inert (can be chemically desinfected), and it is temperature resistant to 150...200°C (can be autoclaved). Solvents like alcohol do get into the silicone, since it is a little bit porous to oils and solvents (not to water: it repels water), but they do not destroy it. Maybe you might want to contact a special effects shop, or people in the special effects branche (film studio, art school), and ask how they would do it. They use these things daily and have much more experience than I have. And they will know all the risks and caveats. I only use silicones occasionally, and then only a few dental versions.
  3. I believe most 3D-printed full color models are painted or plated afterwards, like the excellent art we see from kmanstudios and cloakfiend. Full color models produced directly on a gypsum-powder based 3D-printer tend to have a quite rough structure, like sandstone. Like any gypsum model. After printing they are impregnated with a cyanoacrylate glue to make them stronger and smoother. But it is still gypsum, so if you drop it, it chips or breaks like gypsum. But if you would be a good traditional sculptor (=in sculpting by hand), but have no experience with 3D-sculpting on the computer, there might be another solution. Based on the photo, you could sculpt the model in clay or plasticine. I have seen a traditional artist making excellent clay models based on only a few photos. And then have that plasticine model or clay model 3D-scanned and cleaned. Save it in various resolutions. After that, you can scale it down to make it fit in the printer. I don't know how well this approach would work, but it might be worth trying?
  4. What about "painting" a glove onto her hands? The first idea is of course latex, but that might *not* be a good choice because it could cause allergies, due to the enzymes it contains. And latex is said to shrink upon drying, so it might cause discomfort. I would not recommend this. Maybe painting liquid and reasonable fast curing silicone onto her hands might work? Silicone is relatively inert chemically, and it is also used in dentistry, and in arts: most soft masks and fake wounds are made from silicone. Be sure to use platinum-cured silicone (=addition cured), not tin-cured because that is not stable and only suitable for single use. Be sure to check they are approved for use on the skin. And even then of course do a test on a very small spot to make sure it doesn't hurt. You can find such silicones in special effects shops for film and artist accessories. But silicones can be hard to remove from any model, due to their accuracy in duplicating shapes: they go into the finest pores, forming an airtight seal. So you might want to lubricate her hands with vaseline or another separator first. Try beforehand if the separator is compatible with the silicone: some products do inhibit the curing. If the scan is accurate enough, you could try painting the silicone (or whatever else product you find) on the scan also. If it has to be a two-piece glove, maybe you could mould-in some sort of clips or locks, to keep both parts together? Apply the first layers, let them half-cure (not liquid anymore, but still tacky), apply the clips or locks, and then apply more silicone until they are fully embedded. Silicone comes in various hardnesses: from very soft like skin, medium like rubber bands, and harder like car tires. Some very elastic, some not. You can often combine them: soft where necessary, and harder where more support is required. On Youtube, search for: body casting and mould making, or: creating silicone masks, or similar terms. There are lots of excellent tutorials. These are in the field of arts and dentistry, but the techniques may be usefull. Of course, only use skin-approved non-stick silicone for mould-making and mask-making. Never use sanitary silicone, which is sticky, and is often quite agressive as it might contain vinegar acid: this could cause severy chemical burns.
  5. It was also my understanding that PLA-smoothing with acetone was due to modifiers, not the PLA itself. But for making our silicone moulds, it works well enough, and it doesn't destroy details. I haven't tried chloroform yet. Have you tried burning colorFabb PLA/PHA Natural (=uncolored)? When I tried burning it in a spoon in a bunsen burner a couple of years ago, it left a little bit of black powder dust, but not much. It could easily be wiped off. Contrary to for example PET which left a thick, glossy, enamel-like coating which was very hard to remove. For the tine holes in UM3 prints: could it be that these are caused by tiny PVA support strings embedded in the model? And then when the support is washed away, it leaves a hole? Just guessing, I don't have an UM3, so no experience. PS: beautiful bronze casts by the way. The grey one, is that also a cast, or a painted print?
  6. Not a solution, but maybe a workaround: if you would print in PLA, have you tried smoothing it with acetone or other chemicals? See the thread and photos of user cloakfiend on acetone-smoothing of PLA on this forum: he has done hundreds of models with excellent results. I also have done a couple of tests on colorFabb PLA/PHA: a quick brush-on of acetone tends to fill the little gaps and layer lines. But it does not fill larger gaps, nor removes features or defects like blobs and strings. See the photos. Top orange: untreated, has small openings due to minor underextrusion. Bottom orange: acetone-smoothed by brushing on acetone: all tiny openings are filled. Green: silicone-impressions of the orange models: they show the irregularities well. Left: acetone-smoothed Center: heat-treated with heatgun Right: untreated Same as above. Don't use heat-treatment with a heat gun: this causes the surface to melt (which is the purpose), but it also causes the entrapped bubbles below to expand and explode, creating craters. Similar to printing wet nylon. The surface gets worse instead of better. Don't leave PLA/PHA in acetone: it penetrates the plastic and damages it. Just a quick brush-on, and then let dry thoroughly. This little block (10mm wide x 3mm high, solid) has been sitting in acetone for about 1 hour, if I remember well.
  7. Ik zie je vraag nu pas. Het antwoord is simpel: gewoon uitproberen... Begin met de standaardwaarden: voor mijn printers (Ultimaker 2) was dat voor PLA: 210°C, 50mm/s, bed 60°C. En dan een testprintje maken, en tijdens het printen in stapjes van 5°C de temperatuur verlagen en verhogen, en gewoon zien wat voor effect het heeft. Idem voor de snelheid, in stapjes van 10mm/s. Voor fijne modellen gebruik ik dikwijls: 25mm/s bij 195°C, 0.1mm layers. Voor ruwere modellen en 0.2mm layers blijf ik bij de standaard. Bed temperatuur blijf je beter af: beneden 50°C is de hechting te laag en komen de modellen los met een plof. Boven de 65°C is de temperatuur te hoog, smelt de onderste laag, en pellen de modellen af van het bed omdat ze te week zijn. Als je dat uitprobeert, blijf bij de printer zodat je die onmiddellijk kan stoppen als de modellen loskomen, anders krijg je een grote bol "spaghetti" rond de nozzle. Als jouw waarden tever zouden afwijken van de standaardwaarden, dan is er iets mis, en moet je echt die hele lijst van gr5 doorlopen met mogelijke oorzaken.
  8. In a plaintext editor, search for "[space] e???? [space]" or something like that, using wildcards, and delete them all? Or set them to zero? I don't know if it would work, but might be worth a try?
  9. My first idea was also: poor bed-adhesion in that spot, maybe due to the nozzle being too far away. But if it is always and only in one corner of the model, no matter where it is put on the build plate, maybe it could also be mechanical stuttering or excessive play, when changing direction? Or both?
  10. I think it was 80°C, maybe 85°C, something around that. If you would have binoculars, or a telescope, you could try to hold them upside-down with the ocular very close to the model, close to a bright light. Quality won't be good, and you will get a lot of deformation, but it might be good enough for inspection. A telescope works exactly opposite to a microscope: the lenses are swapped (and in real life of course adapted for minimal distortion). In a microscope the little, most curved lense is close to the object, and the flattest and big lense is the ocular. For people who do lots of 3D-printing and post-processing, and who get a bit older (=eyes deteriorating), it might be a good idea to get an old binocular microscope. This makes post-processing a lot easier. I use it daily. Sometimes universities or research institutes sell their worn-out models when replacing them with new ones equipped with cameras and all sorts of fancy stuff. But for our kind of work, 40 year old models are good enough, provided that the lenses are still good.
  11. If the filament is swollen above the nozzle and teflon coupler, could it be that your little fan that does not work (=the one behind the nozzle)? Sometimes, strands and hairs of molten filament get sucked up in it, and slow it down. Anyway, if you would want to do atomic pulls, but in a much more gentle way without brute force, you could try my old manual: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ And then scroll down a little bit. This works by cooling deeper, and then gently wiggling and rotating, instead of brutal pulling. No risk of bending rods or displacing nozzle parts. But it is equally effective for me.
  12. Is it scratching the surface, or is it entrapping air bubbles inbetween both layers, when seen through a microscope? This also makes it opaque like frosted glass. I only have seen the entrapping in my tests: mostly in the seems between the little sausages, sometimes on top of surfaces as the top layer is not perfectly flat. (In case you don't have a microscope, sometimes a high-resolution camera with powerfull macro lens can also show this, better than with the naked eye.)
  13. Try using standard nylon hardware: there do already exist thousands of different things: screws, pins, nuts, clamps,... These will be much stronger, have a stable size, require almost no post-processing, and in the end be much cheaper. Maybe these will fit, or only require minor changes to your models to fit? In Belgium and the Netherlands, Essentra Components (previously Skiffy) has a good range. But also RS Components, Farnell and lots of others do. https://www.essentracomponents.com/en-nl If you want to print it yourself: - If you print it horizontally, it will be by far the strongest, but not cylindrical. Then it will only be half a cylinder, and probably have a flash or elephant feet at the bottom. - If you print it vertically, expect overextrusion, lots of blobs and deformations, and a very weak model that breaks easily, especially for high-temp materials like nylon. And expect it to wobble during the print causing a deformed rod, and likely fall over. I am not saying it is impossible, but for very small objects, you will have a hard time sorting these things out. If you use standard injection moulded nylon parts, you don't have these problems. Typical deformations of small, vertically printed items: Insufficient cooling due to the nozzle staying on top of the tiny area, so it does not solidify. Cones are 20mm high x 20mm diameter. Lowering temp does reduce this effect, but also reduces layer-bonding: not a problem in PLA but for sure a problem in nylon. Insufficient cooling, overextrusion, strings and blobs in vertically printed models (ca. 20mm high, printed at different temps and speeds). Less deformations but some flanges in horizontally printed models. So this is what you should expect.
  14. Older versions of Cura don't allow parts to overlap: if you place them too close together, one will jump away to a safe distance. I don't know how the most recent versions do this, probably the same? Most of the time I place all models into one CAD file, so Cura sees it as one model. For their placement, I use common sense: I place them as close together as practical, so that they won't fuse, and so that I can still grab and wiggle individual parts to remove them. For narrow but high parts (e.g. vertical rods), I make sure the brim overlaps, which gives much more stability against falling over. Or I design a custom brim and sideways supports in CAD to provide the desired vertical stability.
  15. I believe it often has to do with "the shortest distance between the end of the current item, and the next item". So when the nozzle finishes one item, it will search for which next item is closest by from its current position. I think... Correct me if I have this wrong. At least, I found that carefull aligning indeed helps often, but not always, to improve printing order. As Cymon said above, I would also align the long items much compacter, maybe even so close to each other that their brims overlap so they combine into one big brim. Gives less travel time, less leaking while traveling, and often print quality is somewhat better in the center of the glass than on the extremes.
  16. A few years ago there have been discussions among people using ceramic plates or tiles instead of glass? I don't know if that has been developed further, and if it could be a solution?
  17. I doubt if 3D-printed plastic moulds can handle the mechanical load? I have had two-component resin parts shattered and flying all across the room when subjected to a load of only 5kN (500kg). Most injection moulding machines go up to metric tons. You would also need to polish the mould-surfaces quite well to be able to release the parts, removing all layer lines, and you probably still need to use a lot of release spray. But it might work for making chocolat or gummy bears though... :-) If it would be for industrial/prototyping use, what about a cheap aluminum prototyping mould, for up to 10000 copies? I think companies like Protolabs can do this?
  18. There do exist wrenches that grip on the sides of the nuts, not on the corners: these can be used to remove damaged rounded nuts and bolts. Search for "metrinch". If I remember well, the name comes from the fact that these can be used for both metric and imperial sizes. Anyway, be sure to use two such tools to grab both sides, so you don't apply torque to parts that can not handle it.
  19. Good idea. Such scales should have been moulded-in on each spool, for both 2.85mm and 1.75mm filaments. That could easily have been done.
  20. Heb je alle punten op gr5's checklist al geprobeerd? Die is ergens te vinden op dit forum, maar ik weet niet precies waar. Daarop staan zowat alle mogelijke oorzaken. Ik zou in de eerste plaats denken aan versleten teflon coupler, 3e fan (kleintje achteraan) die niet goed werkt, te dik of slecht filament, te snel of te koud (voor die snelheid) printen. Maar er zijn er nog tientallen.
  21. Indeed, years ago when deciding if and how we were going to step into 3D-modeling and printing, a brand with a good forum was a make-or-break point for us (this in addition of course to other breakpoints like: open filament system, multiple materials, relatively open source, good availability of spare parts, nearby dealer,...). We knew that the learning curve would be high, that we might run into problems, and that we might need expert advice from more experienced users. So before deciding on any printer, I visited the forums first. And I went to see the dealer.
  22. Using two-part moulds will for sure cause the silicone to leak, if it is a slow curing one (>10min). A very fast curing one (<5 minutes) might not leak too much. Unless you fill the seams. Silicone leaks through microscopic pores. A common method to seal the seams, is to use plasticine or wax. But it has to be a plasticine that is compatible with silicone, it should not contain any sulphur (plus a lot of other stuff) which inhibits curing. Do a compatibility test before with a little bit of silicone and the plasticine or wax. You can find good tutorials on Youtube. Search for: silicone mould making and casting. Concerning details: if you use good silicone, *everything* that is visible in the mould, will be visible and mirrored in the casting, just everything. Silicone reproduces up to microns. So: all layer lines, underextrusion gaps, blobs, strings, fingerprints in plasticine parts, nail marks, hairs, dust, any defects,..., all will be horribly visible. And you may have entrapped bubbles if you don't remove them by vacuum after mixing both parts of the silicone. Another way to reduce bubbles, is pouring the silicone in from very high in a very thin stream. And gently (!) blow on bubbles, or prick them with a needle. If you have a shaker while pouring in the silicone, that also reduces bubbles: maybe try an electric tooth brush, or your girl friend's pleasure toys. :-) Do a lot of small test prints, before doing a big one, just to get familiar with the materials.
  23. I haven't had NGEN warping and coming off the bed, but I haven't printed big items either: mine took maximum 3 hours and were low flat models. PET sometimes did warp if printing on bare glass, in the beginning when I used 100% cooling. Now when using no cooling, it does not warp anymore. But here too, my models are low and flat, and take maximum 3 hours. So, try to print without cooling if the model allows it (=no overhangs, no bridges), or try a good bonding method. I used gr5's bonding method a couple of times (=white wood glue 10% dilluted in water) on models that needed cooling, which gives excellent bonding. But that bonding is sometimes too strong and might chip the glass, depending on the model... The problem with no cooling for PET is that it tends not to pull nice strings when bridging, contrary to PLA. PLA gives really nice bridges. But PET-bridges tend to snap and fold back onto the nozzle into a blob: it is too rubbery. So the gap or bridge isn't closed. And that blob gets deposited onto the next wall when the nozzle arrives. The accumulation of blobs will finally close the gap, but it is ugly. At least, that is with the PET I have here... So it may take some trial and error to find the right balance. Before doing long prints, make a small test print that will undergo some load, for example a clamp. And try if that survives well in your car, under load. Or try it in a test-environment at the same temperature.
  24. Before ordering on any website, always check if they have an official address listed on their site (company, street + nr, city,...), phone and email, officially registrated business numbers, etc... And then look it up in an official phone directory, and on Google Maps. If you can see the company logo in the street view on Google Maps, it is probably okay. However, if the company is located on an abandoned garbage pile on Google Maps, better be cautious.
  25. I usually design custom supports, so that I can make sure that I can get in there with a knife, or get in with pliers and hooks to pull out the support. In custom support I can also increase or decrease clearances as desired. Some of my usual examples, in case you need ideas: Various support concepts. The ribs (0.5mm wide, 1mm aparat) on top allow tighter clearances. Orange and pink are supports: they have extensions so I can grab them with a plier, as the model is too tiny to get in with a knife. The brim is for added bonding, due to the large overhangs (they float above the yellow). A totally free hanging support: easy to remove, consumes very few material, and does not damage the underlying parts. The inverted staircase at the underside of the support reduces its tendency to curl up, compared to a triangle shape.
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