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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 needed when printing the tiny top area, so the rest is empty: Another real model, with dummy (red). Here too, the dummy is empty, except for the top where it is needed:
  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 hot, this salt method greatly increases bonding. But it has no bonding at all after cooling down. However, on PET this slightly *reduces* bonding, but also makes removal much easier, compared to printing with dilluted wood glue or bare glass. Disadvantage is that I have to switch off the cooling fan, otherwise corners tend to lift a bit. No cooling does reduce the quality of overhangs and bridges a lot. But most of my models have no overhangs anyway, so not really a problem. The ease of application is the biggest benefit: just wipe the glass, and ready to go. No need to take the glass out of the printer. When trying new bonding methods: stay with the printer, and watch what happens. So that you see how it works, and you can stop the print in case models come off and produce spaghetti or slide around under the nozzle. These models are in PET, bottom-side up: notice the little pits from the salt crystals, and the nice flat surface, squeezed well into the glass. For reference: ruler is in mm and cm. This is what the glass looks like after applying salt water, and wiping it dry. This is a bit too much salt. This is a better amount of salt. (Don't mind the spaghetti in the print: these are free-hanging supports to print a bridge, and will be removed later. This print is PLA, not PET.)
  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 thick and gives lesser bonding than 0.2, especially for objects with very small holes like in my photo above. Everyone has his own taste: I like the simplicity of manual leveling, like manual shifting in a car, and a manual handbrake. :-)
  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 shapes, not for smooth organic shapes. But there are other free CAD editors. Take a look at demos and tutorials on Youtube, and find one that appeals to you.
  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 print each one flat on its back. And then assemble and glue it like Faller HO model railroad houses. Probably... And what about glueing the original, and maybe reinforcing weak areas with some glued-on metal plates, or metal-containing self-curing putty? Or glass-fiber tissue and epoxy, like in car body repairs?
  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 comes to mind, but if you already cleaned that area multiple times, it shouldn't be... Photo of typical bottoms of my prints (this is PET):
  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 the print, e.g. 80°C. And then let it sit for the night at that temp. In the morning, see if corners have lifted, and try pulling it off. But of course without brute force, always gently. If you print a tiny cube of 10mm, if the bonding is good, you can't pull it off. If the bonding goes bad, you can. But again, always be gentle. Forgot to mention: also consider using a brim: maybe in Cura, or as a custom designed brim (=designed in CAD, as part of the model). This also helps reduce corner-lift. I guess you are going to print the pale lid on its back, thus with the huge tabs facing the glass? In that case, consider free hanging supports for the tiny overhangs for the screws. But again: first test this concept on a small test model. Custom brim around the left model (the right one is post-processed and polished): Custom brims designed in CAD around the pink and orange supports, and around the cube: Free hanging supports: Other view of the free hanging supports: they are kept in place by the strings from the material, and are thus very easy to remove: Cross section. The ribs on top of the supports are 0.5mm x 0.5mm. The inverted staircase at the bottom of the supports is 1mm x 1mm. The gaps and little "connection tabs" are designed and tested for this particular model, you may need to change dimensions for yours. Hence the need for a tiny test model, containing only this concept.
  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 blob hanging on the nozzle is deposited onto the next wall that it encounters, creating a sort of "insect antennas". See the pic below. But I could imagine that if that blob encounters a thin perpendicular strand, as in your infills, it would hit that, and maybe snap it? I am just wildly guessing, because I have never seen that myself... Using a magnifying glass, try having a very close look. Maybe you can see what happens? (And if you find out, let us know.) Photos: Close up of "insect antennas": Next to a ruler (mm and cm):
  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, such as bonding that might reduce with time. But then at least you get the overhangs and bridges good.
  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. Then remove the plaster cast, and carefully sand it and correct minor defects like bubbles. And use that plaster cast as mould to vacuum thermoform your car, using a somewhat flexible plastic sheet. In this way, you can always re-use the mould to quickly produce new body shells, for painting in different color schemes, or when one gets damaged in a crash. You can buy a commercial vacuum thermoforming kit, or make one yourself. Take a hard wooden plate, MDF or multiplex or so, for a base plate. Drill a hole in it and attach a powerfull vacuum cleaner to it. Then make a double frame out of wood, of the same size as the base plate. You need to clamp both frames on top of each other, so you can clamp a sheet of plastic between those frames. Once clamped in the frame, heat that plastic sheet with a heat gun untill it really sags. If you poke into the sagged plastic with a tool, the dent should almost immediately straighten out again. (If it doesn't, it is not warm enough yet.) While heating, switch on the vacuum cleaner. And then when hot enough, pull that frame with sagging sheet over the plaster model, so it gets pulled vacuum around the plaster. Let cool, and remove. I had a small professional unit for dental models some years ago, but the principle is the same, and I have seen home-built models. Maybe you can find Youtube videos?
  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 guess it must be something along these lines...
  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 tiny undercuts, and make it very hard to remove the cast. Any layer lines are also terribly visible in the cast, and they make the cast sensitive for dirt. (You are probably well familiar with the other normal moulding aspects like: no undercuts, venting openings, alignment features, clamping features, etc...) Chemical smoothing might also be an option: I sometimes use dichloromethane. See my recent post here on PLA and PET smoothing with dichloromethane. This greatly reduces layer lines. One of these models is chemically smoothed, reducing the layer lines; the other is as printed.
  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 deformation. And cooling is difficult and slow, as the heat from such thick sausages takes time to radiate out, so it tends to sag while cooling. It has a nice sparkle in it though for transparent materials. From left to right: layer height = 0.4mm, 0.3mm, 0.2mm, 0.1mm, 0.06mm. Top row printed at 50mm/s, bottom row at 10mm/s. This is clear PET. The brown discoloration is because it is staying long in the hot nozzle at low speeds and thin layers.
  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 simple but usefull models at various settings. Keep watching while printing, so you see and learn what happens.
  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 understanding and wider viewpoint yourself, and your viewpoints will be more appreciated by others, because what you told earlier, did work. And if they later find new solutions based on your help, they will often come back and tell you, so you learn from that too. So, practically, if the client is not too far away, just go there for a couple of hours, or even an afternoon. Have a nice chat, have a look at their systems and their workflow, and find out and explain them how to to it correctly. Most people are smart people, who just lack some technical knowledge. When someone is lacking the grammar and vocabulary of a language, he can not speak it, but he is not dumb: he can learn it.
  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 to cause underextrusion: - When the teflon coupler is worn-out: if you do an atomic pull, and there is a thick sort of ring or blob at the edge between coupler and nozzle, then it is worn-out and needs replacement. See the pics below. - When the filament spool is nearly empty, especially when printing hard filament like PLA: the hard filament acts like a strong spring, that resists unwinding. If you have a very hard time unwinding it by hand, then the feeder has so too. - When printing in the back-left corner: then the filament has to make a very tight curve in the bowden tube, and this causes a lot of friction in the nozzle and bowden tube. - When the nozzle is partially clogged by accumulated dirt and coal on the inside of the opening. Regularly do a cold pull to keep it clean. - And obviously, when all the above are combined. There could be lots of other reasons too, such as incorrect filament diameter, or dirty feeder wheels or damaged feeder, but the above I found the most common for my system. User gr5 has a good list of causes of underextrusion, so try to find that. As bonding method, for PLA (not for other materials) I only use my "salt method": after thoroughly cleaning the glass, I put a few drops of salt water on it, and wipe that with a paper tissue until dry, so it leaves a very thin mist of salt on the glass, almost invisible. This greatly improves bonding compared to printing on bare glass. When printing on bare glass, the results are very dependent on circumstances: it may bond reasonable well in very dry weather (like freezing cold), but it may not bond at all in moist weather. The salt method works very well for me on long and low models, like rulers, at 100% infill: they stick like rock. But not so good for thin and high models like lantern poles: these might get knocked over. Have a look at my salt method, and my gentle atomic pull method here: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ Pictures: 1. If you think friction due to the end of the spool being wound too tight, and too hard to unwind: manually unwind a bit, and wind it in the opposite direction around a skater wheel, thus bend it in the opposite direction. Then let go and do the next part. So it sits very loose on the spool, has the same bending-radius as the bowden tube, and causes almost no friction and no resistance when unwinding and transporting through the tube and nozzle. 2. These kind of long low models print very well using the salt method: I have done many hundreds without any problem. 3. The thick sort of ring or blob in the white filament after an atomic pull, indicates that the teflon coupler is completely worn-out. When printing, half-molten filament gets stuck in that widened area, and causes underextrusion. It should look like the orange one at the bottom here: totally straight. The other two were pulled-out a bit too soon, before the filament had completely solidified. Obviously, these were all done while changing color, to remove remains of the old color from the nozzle. Also check if the cone-shape is good, like here.
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