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geert_2

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Everything posted by geert_2

  1. If I had to do that, I would consider printing a mould, and then cast some sort of rubber (PU? - which exists in various hardnesses) into it. Or print a real model, print a shell, pour silicone in-between model and shell, and thus make a silicone mould. And then pour rubber into that silicone, to prevent it from sticking. Then you have the advantages of both 3D-printing and casting.
  2. I would print a dummy "cooling tower" next to the real model. So the hot nozzle is moved away from the model, while it is busy printing the dummy, and the model has time to cool down and solidify. Where the bottom of the dummy is empty, since the real model is big enough, and the top of the dummy is 100% filled for the extra cooling time. My standard pictures on the subject: Printing with and without dummy: Concept: inverse shaped dummy, to keep printing time per layer constant: Part of a real model, with pink dummy. The dummy is only
  3. I occasionally print PET. In the beginning I tried printing on bare glass, which gave mixed results. Then I tried dilluted wood glue, which gave *very good* bonding. Way too good, because at one time, it chipped the glass. This already happened while cooling down, I heard it crack violently. When I removed the print, it came off without any force, but with the glass chip stuck to the print. Now I use my salt method: apply a few drops of salt water to the glass bed, and wipe that with a paper tissue until it dries into a very thin mist of salt. For PLA, and as long as the glass is h
  4. I don't see any underextrusion or broken lines any more. A couple of blobs and what appear to be "insect antennas" (at the right, but hard to identify in this picture), which is what you can expect with PET in my experience.
  5. If the rest of the part was still okay, thus not worn-out and not brittle or crumbling apart, and if it was my machine, I would probably consider modeling only the damaged areas. And then cut these off the original part, drill a couple of holes, and bolt the new 3D-printed parts on, using a M4 or M5 bolts and nuts. That is, if there would be enough room for that in the machine and in the part, of course. But this won't work if the original is crumbling and too brittle (it looks a bit like that?). It seems to be an ABS-blend, as I noticed the words ABS on the side.
  6. I have manual leveling on my UM2 printers. I did that according to the official procedure in the beginning. Since then I only adjust it occasionally on the fly. I start a print with a thick skirt (5 lines or so), or when printing the brim if I use brim (rarely), and then I watch closely how the first layer is, and adjust on the fly by moving the screw a 1/8 of a turn, and then watch again, etc. I think it is a little bit closer now than originally, indeed. But I only adjust that maybe once a year... My bottom layer is 0.2mm thick: I found that 0.1mm is too thin and a bit uneven, and 0.3 is too
  7. Wow, these are really impressive paintings. They look like the antique art you would find in museums. When priming your paint spray cans, maybe you could do that on a plain sheet of white paper, or sheet of wood, and keep this sheet with all color patches, and make photos of it? This would give an impression of each of the colors and effects on its own. Question: before painting, do you chemically or mechanically prepare the surface of 3D-prints, for a better bonding? And do you use primers that chemically dissolve and penetrate the plastic, or do they just coat it?
  8. I guess there are defects in the model. SketchUp is going to cause you endless headaches and problems: it does not close its vectors, so the models are not watertight solids, but sort of "glued together paper models". And it often has duplicate walls and other defects. It was only made for visual representations, not for 3D-printing. It will probably take you far less time to find and learn another CAD-editor, than continue in SketchUp. I am using DesignSpark Mechanical from RS-components, free but requires registration. However, this is only for geometric technical sha
  9. Are you sure this is the only thing that is broken? And there is not some other fault (maybe electrical or electronic)? I would say: if you do have standard PLA, try that and do a *cold* wash (=max 40°C) to see if it works now. Only then go for a more suitable material (but I can't give recommendations, lack of experience myself of heat-resistant materials). Do the parts have to be so thin, to fit well, or is there room for thicker parts? If I had to do this, for a first prototype to test the fit and function, I would cut it into pieces, so that I could prin
  10. Yes, irregular temperature could be a factor: I once measured it, and at the edges it could be quite a bit lower. Maybe due to the rising hot air pulling cold air in from below. Also, under the nozzle-fans the bed can be much cooler, especially on small objects where that fan is continuously blowing on a small spot. Also check the bottom surface of your prints: is it squeezed equally flat in all areas? Maybe if one corner is too far off, the filament is not squeezed well, and that could cause it to bond less. See the pic how my prints typically look. Grease or oil also
  11. My bad, I had missed that printer-info. Yes, trying a higher bed temp might also be a good idea: mine is around 80-90°C for PET (I don't know by head, but I definitely increased it from the original 70°C). The bed temp has te be close to the glass transition temperature, where the material starts to become soft. If lower, bonding reduces. If higher, the part may become too soft and sag, warp or peel off. What you could also try if you suspect time reduces bonding: *immediately* after a small test print completes, manually heat the bed to the same temperature as during t
  12. My brand of PET does not like traveling through the air, not for bridging, and not for crossing gaps to the next part. There are two problems: 1) It does not pull a nice long string for bridging, contrary to PLA: PET tends to snap and scroll back onto its own, like a rubber band that snaps. This causes a blob hanging on the nozzle, instead of a bridge. 2) When liquid, PET is more rubbery than PLA. So, when crossing gaps, the pressure does not release as fast in the nozzle, causing the nozzle to leak a bit more while traveling over gaps. In both cases, the bl
  13. Without knowing your model, your printer and your particular CPE, I can only guess... The best thing you could do, is cut out the most critical and most representative parts of your model, such as overhangs or bridges. And combine these into a new *small* test model which takes only maybe 30 minutes to complete and doesn't use much filament. Test and optimise on this until you get it good. Overdo in one direction, then overdo in the other, and gradually find the optimal center. This is going to cost time, but you learn quickly. Of course there can still be scaling problems later on
  14. Did you switch off the cooling fan? Or set that at a very low speed? For PET, which I think is very similar to CPE, I always print without fan if the model allows it, thus if it has no overhangs and no bridges. Otherwise I use the absolute minimum amount of fan. I usually print PET on bare glass. (Although some say this is not recommended, as it might cause a too good bonding, and might chip the glass.)
  15. I am also not sure if I get it? If you need a sort of filter, couldn't you print something like this? Laying flat instead of upright? This is a sift for the sink drain in my lab. If not the filter itself, but just to encapsulate and support a filter, then you could do way bigger holes for less aerodynamic resistance.
  16. Yes, vacuum thermoforming might be a good idea. I think most commercial RC car kits are also vacuum formed? But I am not sure if you can vacuum thermoform around a PLA model, without it being deformed due to heat? Also, it might not pull vacuum very well, since the air can not escape from deeper areas. However, you can definitely vacuum thermoform around plaster. That is how some dental applyance are (were) made. Plaster is porous and lets enough air pass through. So you could 3D-print a mould in PLA in multiple parts (to be able to release the cast), and then pour plaster in it. T
  17. With DesignSpark Mechanical I also never had any problems: always correct solid and water-tight models, always nice on the build-plate, always correct size. But it is not suitable for artwork, only for technical models based on geometric shapes. I had occasional problems, but that was when I had made modeling errors, thus operator-errors, not software-errors.
  18. Just out of curiosity, what price are they asking, order of magnitude? (I have no interest in buying, I have enough machines myself.)
  19. It is not clear from your photos, but it looks like the part came off the glass bed, and started sliding around? If yes, the problem could be your bonding method (or the lack of, or you forgot to use one), or a bed height leveling problem? If the model would still be stuck to the glass at this point, then maybe you have loose pulleys somewhere, maybe on one of the stepper motors? Or maybe something hit the printhead while printing (cat, dog, kid,...?), causing it to skip steps? Or printing too fast for your stepper motors, so it could not follow and skipped steps? I gue
  20. The two-shell concept of gr5 might be worth considering, at least for those areas that need most detail. In injection moulding this is also used: the main mould gets a cruder finish, while areas that need lots of detail, like fine text or optical lenses, are done with a smaller insert with high quality finish. It do not need to be complete sleeves covering the whole model, maybe a smaller area is enough, depending on the model. I have made several PLA moulds for casting silicones. The most important aspect is to remove layer lines as much as possible. They act like a zillion of tin
  21. What is good enough depends on the model and application, of course. But 0.4mm from a 0.4mm nozzle as in the pics below, is moving away from the optimum. I think coloring it orange is good, meaning: "possible but not optimal". But maybe make that color a bit more gold-orange instead of deep orange (e.g.: RGB=255,180,0), so it visually moves further away from the red? Both left blocks in the overview-picture are 0.4mm layer height, from a 0.4mm nozzle. Top row printed at 50mm/s, bottom row at 10mm/s. It prints well, but you have very crude layer-lines, and you start to get deformati
  22. In addition to the above: - Glue suitable for the filament you use, e.g. cyanoacrylate for PLA. - A drill for *manually* cleaning small holes (see picture). - A very thin needle (0.39mm) in case the 0.4mm nozzle would clog. Be sure to round-off the needle tip, so it does not damage the fragile and soft brass nozzle. - And indeed, all tools you would use for model airplanes, cars, trains,... - Tissues for cleaning the nozzle immediately after printing, to keep it clean. - A sealed box, with a bag of desiccant to store filament dry. And then try a lot of
  23. For cleaning, don't use soap: that reduces bonding. That could well be the reason for your warping. Or do it the other way round: first soap water (like window cleaner or Mr. Proper), then isopropyl alcohol, and then with pure handwarm tap water only (but no soap). After using alcohol, don't touch the glass anymore on the areas where you are going to print. Finger-grease also reduces bonding. Also very moist and rainy weather might reduce bonding, when printing on bare glass. That is why I started searching for a new method, the salt method.
  24. Indeed. I am a big fan of educating people (although in my case the "clients" are PhD-students and collegues), so that they *understand* what they are doing. Not just verbatim duplication like a parrot, but real understanding, so that they "see it". That sometimes takes hours. And then it saves me days and weeks of time, because next time they can solve it themself, and they can often do it faster than I could (which is very good). Additional benefits are that they become way more happy. And you become more influential, because with each problem-solution you teach them, you also get a better u
  25. I may have missed it in the posts above, but I didn't see what bonding method you used? Could you describe that, thus method-name and exact procedure? That could be a reason too for the warping? Also describe the cleaning method you use for the glass? And the weather conditions in your environment now, temperature and moisture-level? These all play a role too in bonding, in addition to bed-distance and underextrusion. Since it isn't solved, it is best to go over each step again. For underextrusion: on my older UM2 (non-plus), there are a couple of things that are likely
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