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geert_2

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Everything posted by geert_2

  1. In addition to the heat-problem described by |Robert|: The resin will most likely glue firmly to the PLA. You would need a very good release coating to prevent that. Test the compatibility of the release sprays or coating with the resin: if incompatible, it might prevent curing, and you would end up with a sticky mess. Release-sprays might make painting difficult; you would need to degrease thoroughly. Concerning heat: in the old days, when mixing epoxy resin in plastic cups, or even in metal (lead) cups, I often saw these melt due to the heat in the left-over resin. So you would need a slow-curing or low-exotherm resin. If you keep these things in mind, I think it is worth trying. Another option would be to make a silicone mould from a 3D-printed part, and use that silicone as base for applying the carbon fiber and resin. Silicone can withstand much higher temps, and it is by itself non-stick. But even then, thoroughly applying release spray greatly increases mould-life. Silicone is porous for oils, solvents and resin-vapours: so they would soak in, and over time cure in there and destroy the silicone's flexibility.
  2. And try all these things on a *small* test piece first, so you don't waste too much time and material. First inspect in Cura layer-view if the infill pattern does what you want, less or more, and only then print a small test piece. Maybe another option might be: 3D-print a *heavy solid* mould, ply anti-insect mesh over it, and use that mesh as mould for your paper? If you use stable steel or brass mesh, it might be strong enough? Or something else along this line of thinking? You might be able to use gypsym bandage too, like the ones used in hospital for broken legs? Then you could use the 3D-print as mould for the gypsum. Gypsum is porous and can let some air and water through, but maybe not enough for your application? Edit: the advantage of gypsum and metal mesh is that you can heat them, e.g. with a heat gun, to speed up drying. You can't do that with plastic moulds.
  3. I don't have much experience with it, but ABS is said to decompose fast in the nozzle, if sitting there for too long (=or too hot, or printing too slow), causing clogs. If that is not the case for you, then have you checked that the little fan for cooling the nozzle is working well? On an UM2 this is sitting behind the nozzle, invisible from the front. I don't know where it is on an UMO. This could suck-in hairs and debris, and get stuck. Also on an UM2, a severely worn out white teflon coupler could cause underextrusion after a while. I don't know if an UMO has something similar? The white filament-end after a cold pull on an UM2 shows a thickening where the teflon coupler is worn out. But I have seen even worse. This hinders the material flow. Not sure if any of these could be the cause for you, but it might be worth checking?
  4. Ah, okay, I missed that "straight through" part. I don't dry PLA and PET. Although I do store them in a box with dessiccant. But while printing I just leave them in the printer, sometimes for several days or even weeks. Doesn't seem to make much difference. PET seems to be a bit water-repellent. And PLA seems to get a little bit duller over a couple of years time due to degradation, but I am not sure if that is mainly UV-light, or due to moisture, but it is going *very* slowly over years, not days or weeks. If I would use nylon or ABS, I would dry them though.
  5. I made a tool to scrape off this primer. It is plied from very tough steel spring (same as used in dental appliances for kids, 1mm thick), so it clamps very well and does not come loose. It hits the nozzle, bends downwards (it's a spring), and scrapes off the blob. Works very well 99% of the time on both of my UM2.
  6. Does it crack along the layer lines, or does it completely ignore layers and go diagonally through them? My experience with PET is that it is less strong than PLA, it will break sooner under high loads, but it can flex more. It will fracture without warning, all of a sudden. Fractures ignore layer lines (indicating good bonding). Also, it has less creep due to permanent loads than PLA. So for keychain mechanisms, carabiner hooks, and snap-fit locks it is better than PLA, since they need to flex to function. However, the PET keychain will break much sooner when it gets stuck in your pocket when you sit down. So it is far less forgiving than what you would expect, based on experience with cola/water PET drink bottles. I print PET without fan, but at low speed and very low temp: the absolute recommended minimum, or even less: 210...215°C (recommended: 215...250), for 0.1mm layers, and 25...35mm/s. A higher temp did not improve quality nor strength: it caused bubbles and more stringing. The downside of no-fan is that overhangs and bridges are terrible, but for my long and flat models this usually is no problem. Using fans decreased layer bonding, and caused a tendency to warp in long flat models. (I print on bare glass, wiped with a tissue moistened with salt water.) Printing extremely slow (10mm/s) causes the material to get brown, thus indicating beginning decomposition in the nozzle, but it gives excellent bonding (plenty of time). So I do think that some decomposition occurs, and that the indents caused by extruded sausages may concentrate stress and initiate cracks, and make it fail much sooner than injection moulded parts. Not sure about crystalisation: I don't see it getting opaque. But I am no chemist, so maybe I can't recognise it. Anyway, try various settings on small test pieces, before doing large models. That is why I do the keychains, and I use them every day in my pockets. :-) See my comments and photos in this thread: https://community.ultimaker.com/topic/30778-printing-airtight-with-petg/?tab=comments#comment-254606
  7. The fact that 3D-printing produces smell, means that it produces gasses and/or particles. Composition and long-term effects might not be totally known, in new and rarely used technologies (=rarely used compared to the number of people in general). So I think it would be best to provide some sort of fume extraction anyway, even with the cleaner printing products like PLA and PET/polyesters. Maybe similar to the one in a kitchen? Or a simple pipe with fan that you place close above the printer? If you can not get the exhaust pipe to the outside, you could use a system with active carbon filter. Google for ideas and options. My printers are sitting in a fume extraction cabinet in my laboratory. This is an expensive thing (5000 euro?) and way overkill, but I had it anyway and didn't use it much, so.
  8. That exFAT is probably going to be the problem? I would suggest you buy a couple of thumbnail 8GB or 16GB sticks, and just leave them with the printer. I guess USB2 would be preferable over USB3? Theoretically it should make no difference, since USB3 is downward compatible, but you never know? And speed is obviously of no concern here. :-) They cost less than 10 euro/piece these days. A tiny little thumbnail stick doesn't stick out too far, so less risk of hitting and damaging it. Make sure they are FAT32. I once tried reformatting a 64GB exFAT stick into FAT32 (for another purpose, not for 3D-printing), but that didn't work well. Had to reformat it back to exFAT.
  9. I never tried it, but I would think the "dot-method" would also work with stacking, on the condition that you merge your model-stack in CAD. And export the whole combination as one STL-file. But obviously you are going to need a lot of support material if the models would be irregular, and I think the risks of something going wrong could increase as you get higher in a stack, e.g. support and model not bonding well, or underextrusion, or running out of filament... So while I do understand the desire to print as much as possible in one batch, especially if you are on tight deadlines or have a high volume to print, it is not something that I would like to do for myself. But it might work well for flat models like coins, or walls of architectural models. So this would be the concept, in perspective and side view (just a quick and dirty sketch, don't mind the non-optimal positioning):
  10. I have two UM2 (non-plus, thus the version before the UM2+) printers and they are still fine for what I need them for, mostly long flat models that need no support. So if you only need one color and no dissolvable support, it should be okay. But I would suggest that you make a testprint first, to see if everything still works fine, and the printer isn't abused or damaged (e.g. by dropping, printing abrasive materials, things burned out, damaging mods,...). This is usually repairable, but then the costs might no longer make it the best choice.
  11. No, I didn't change the flowrate, so it was the standard for PET on my UM2, and I left it at 100% on the machine. I had to look up temperatures for these test blocks (I had written it down somewhere): - all were 215°C, except: - 0.06mm layers at 10mm/s (unpolished block) = 210°C - 0.06mm layers at 10mm/s (polished block) = 200°C - 0.4mm and 0.3mm layers at 50mm/s = 225°C due to the much higher extruded volume The recommended temp range by the manufacturer is: 215...250°C, so I am at the lower edge. I once tried higher temps too, but that gave more bubbles and more stringing, and faster decomposing and browning. By the way: test blocks are 10mm x 20mm x 10mm, and watermarktext is 3.5mm caps height. I don't really know about part-strength vs. layer-height. But from these tests it was clear that thicker layers and faster speeds gave more "frosted glass effect". That means more voids, and probably less strength (but I am guessing now). Printing at 0.4mm layer height was still possible, but then cooling became an issue: the block didn't cool down fast enough and it started deforming. I would suggest you run a similar test, but maybe with a testmodel more suited for your application and more similar to your final models (e.g. with overhangs and bridges if you need these). This gives good understanding of your printer and your filament, and you will win back that time investment very fast.
  12. On my UM2 (=single nozzle) I get watertight PET parts by printing at low speed, low temp, thin layers, no fan. Usually 25...30mm/s, 215°C, 0.1mm layers, bed 80...90°C, 0.4mm nozzle. But 0.06mm layers are even better. At slow speed, print cool to prevent the PET from decomposing and getting brown. Layer bonding is excellent: when overloaded, fractures run diagonally through parts, disregarding layers. Main disadvantage of no fan, is that overhangs and bridges are terrible since the material won't bridge well. But for my long flat models, this usually is no problem. If you would use PVA-supports on an UM3, any PVA strings might cause holes in the PET. Consider using PET for supports (thus a single material). Print a few small test parts before doing a large real part. Pictures: Test blocks in PET, layer height from left to rigth: 0.4mm, 0.3mm, 0.2mm, 0.1mm, 0.06mm. Top row printed at 50mm/s, bottom row at 10mm/s. All 0.4mm nozzle. Slowest and thinnest-printed test blocks are getting brown due to slow material flow in nozzle. Testblock at 10mm/s and 0.06mm layers, left as printed, right polished. Transparency indicates good layer bonding and very few internal voids. Absolutely watertight. The 3D model. Text is a hollow watermark, sitting halfway in the testblock. Keychains in PET. Ruler units are in mm and cm. Fractured carabiner hook: fracture pattern radiates in all directions, mostly not following layer lines, indicating good layer-bonding. Idem, other side. ----- end -----
  13. Ik denk dat niemand nog een raft gebruikt. Maar waarom zou je niet gelijk op de glasplaat printen, dat werkt prima? Als je perse een soort raft-achtig ding wil, kan je misschien een dunne plaat ontwerpen in CAD, en die printen met beperkte infill (ca. 50%? - Probeer op kleine teststukjes), en zonder top layers?
  14. Maybe move your bed closer to the nozzle, or make your first layer thinner, 0.1 or 0.2mm? I get really glossy bottom layers with both PET and PLA. Print on a glass bed, not on tape or some other rough surface. Hard to see in the photos below, because the reflection is out of focus, but these bottom surfaces are high-gloss and do reflect like shiny injection moulded parts. The "copyright design ..." watermark text is hollow and sitting 0.5mm below this glossy bottom surface. For reference: text caps height is 3.5mm, character legs are 0.5mm wide. High-gloss bottom surface of keychains. The ruler is in mm and cm.
  15. I don't know your printer, so this is guessing. To me this looks like a hardware issue. Maybe some connectors that are not seated well or are oxidated? Or electromagnetic noise on the power line or environment? Motors starting or stopping causing pulses, or sparks you get in cold dry winter weather? Or a cell phone going off nearby? This sort of things can easily lock up electronics. (Cell phone often locks up my USB-keyboard and mouse.)
  16. If you want to examine a 3D-print in detail, but you don't have a microscope or good macro lens. Try using your webcam or smartphone, and add a close-up lens in front of it. Then watch the picture in full size on your computer screen. You could use any old camera lens as close-up lens, provided that it is concave and does not cause too much distortion. Or buy a dedicated smartphone adapter with close-up lens. Magnification will differ depending on its focal length. If required, design and 3D-print a lens holder for mounting the lens onto your camera. The results are not perfect, but not too bad either. Sharpness is okay. There is considerable cushion distortion, but that is not too important for this kind of pictures. The photos below are from a Logitech C525 webcam, and an old ocular camera lens as close-up lens. But the concept should work with any similar webcam or phonecam. Test photos: 3D-printed keychain with watermark text inside. Text caps height is 3.5mm, leg width is 0.5mm, and text is sitting 0.5mm below the surface. Material is transparent PET. Underextrusion test. This is at 50% flow rate. PLA. Insect antennas on a print, after I forgot to enable retraction. A standard Bic ballpoint tip. Micro-electronics from an old video camera (good for recovering lenses too). The resistors (little black things with numbers) are ca. 0.6mm wide x 1.7mm long. Fingerprints. Flintstone-text: here caps height is 3.0mm, leg width is 0.42mm (in the design, probably more in print), printed on an UM2 with 0.4mm nozzle, 0.1mm layers, 25mm/s, 200°C, PLA. The equipment: Logitech C525 webcam, with an old camera ocular lens attached. Obviously, I still have to design and print a decent lens holder... But any similar equipment with small cam and lens should work. Test subjects, with ruler in mm and cm for reference. ----- end -----
  17. I don't know your printer, so just guessing... Maybe a blocked nozzle, and then the filament cooked, burned, and spilled all over, due to sitting too long in the hot nozzle? Or something along that line, where the filament got stuck? Some materials burn away rather cleanly or leave black coal dust (like the PLA that I have), but some burn into a sort of glossy varnish that is hard to remove (like the PET that I have).
  18. In the beginning I also had this problem. But now it is extremely rare, even though I have lots of models with small openings. Maybe you can solve it by adjusting nozzle height a bit closer, or changing temp or speed of the first layer? Or improving your bonding method? Also, a thinner first layer gives better bonding and less risk of the first outline being ripped off, on my printers. A 0.2mm layer sticks *much* better than a 0.3mm for PET and PLA: this is just my observation, but I am not sure why.
  19. The whole world has switched to the metric system officially, so I think we should stay with the metric system. And not go back to medieval units that don't work well in high-tech environments, no matter how much sentiment there is in it. I grew up with "horsepower" for car engines, which now has changed to kilowatt. I regret this, because the horsepower-number is higher and thus more impressive than kW, and because I grew up with it, but kW makes calculations sooooo much easier. No more weird random conversion factors. The USA has switched to metric in 1875 (yes, 18...), although some politicians and press are still not aware of this, and the UK has switched more recently. Asia is metric since long (except a few former British colonies), and it is quickly becoming the dominant world power. As soon as they have enough power, I am very sure they will enforce the metric system even in the aviation industry, the only industry that currently is still partially imperial (and then even with a bizarre mix of British and US units, and metric, causing confusion and accidents: some time ago a plane ran out of fuel and crashed, killing all souls on board, after confusing metric and imperial fuel units when refueling). If we don't want to be left behind, I think going fully metric is the only option, even though it might hurt our sentiments.
  20. I don't have resonance problems (2x UM2 non-plus), so I can't test this. But I think this is an interesting approach. The only question is: if people notice resonance, how are they going to find out which frequency it is exactly? If I feel a vibration, I can't tell if it is 5Hz, 7Hz, 10Hz,...? At least not without a known reference next to it. Further, it is very hard to feel/hear whether there are lower or higher harmonics on it, which could also trigger the resonance. Maybe you could find a printing test pattern that "resonates well"? Or a printing pattern that causes vibrations at known frequencies, so that people can try this, and then can compare their own resonance to these standard patterns? I am thinking of a gcode-file with a sort of "frequency stepping scale" similar to the E24 resistor values in electronics? Where the actual resonant frequency is displayed on the front panel? And then, if that frequency resonates in the system, people can just read the value from the front panel, and enter that in Cura? Could be interesting from a theoretical viewpoint, but I am not sure if it is worth the effort though, and if it would really result in better prints...?
  21. A few years ago I lubricated the edges of the belts with hard silicone grease, with the same effect: sound gone. It seems to be the edges running agains the flanges that cause it. Only lubricate the edge, not the belt tracks, otherwise they might jump teeth. And don't use petroleum or plant or animal oils or fats: these might damage the rubber. Hard silicone grease is chemically almost inert, and it does not leak away. It is the same sticky stuff used to lubricate movements of binoculars and microscopes, in which you can't have oil leaking onto the lenses.
  22. While I don't have much experience with Ultimaker PLA colors, I only used a few, I have seen a similar effect in other brands. It seems the pigments and other additives to create the desired color, such as filler particles for white, gold, silver, glitter, pearl,..., have an effect on viscosity, stickyness, optimal temperature and flow, etc. Some colors tend to give more strings and hairs, some tend to stick more to the nozzle leaving residu, some tend to show layer lines much harder, some tend to create more blobs,... Slightly transparent colors hide the layer lines a bit better, while white and shiny colors show them more.
  23. To me it looks like your biggest problem at this moment is basic handling of a Windows computer. Starting with 3D-printing is then like trying to do aerobatic stunts in an airplane, before you can't take fly it safely. I think you would make much faster progress if you would first follow a good course on using computers, just the general principles: how files are handled in Windows, how and where they are stored, zipping and unzipping files, installing programs, etc... Yes, this will take you at least several days, maybe a week. But you will soon win that time back 10 times.
  24. I have had this with PET, when using a bonding of dilluted white wood glue. Bonding was absolutely excellent, too excellent. It chipped while cooling down, even without pulling. Now I wipe the glass with a tissue moistened with salt water, prior to printing. This method slightly reduces bonding for PET, but avoids chipping (contrary to PLA where the salt-method greatly improves bonding). PET models that need lots of cooling now tend to warp slightly, but models that can be printed without any cooling come out fine without warping, and without chipping, such as my typical long flat models. After cooling down, they come off easily. If you try this, stay with the printer to see if it works for your models, and if they don't pop off in mid-print. No issues with PLA so far.
  25. Oil *could* be a bad idea, depending on the oil and silicone combination. Some chemicals inhibit curing of silicone, such as sulphur, mint, some oils,... Try compatibility with a little bit of silicone beforehand, or otherwise you might end up with a half-cured mess that is very hard to clean from the mould. Further, make a small test piece first with the same angles of side-walls as the real model, to see if you need smoothing of the walls. Silicone flows into the tiniest pores, so it gets a very strong mechanical grip, even the non-stick mould-making silicones. For complexer models smoothing will be required, just to be able to get the model out of the mould, unless it is very simple and flat like coins. Also preferable use platinum-cured silicone (additive cured). No tin-cured, as that tends to decompose over time, and is only good for short term use.
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