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geert_2

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Everything posted by geert_2

  1. 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 thoug
  2. 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.
  3. 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
  4. 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 car
  5. 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
  6. 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 h
  7. 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.
  8. 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 bu
  9. 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.
  10. 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?
  11. 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-g
  12. 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.)
  13. 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
  14. 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).
  15. 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.
  16. 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...
  17. 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
  18. 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.
  19. 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
  20. 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.
  21. 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
  22. 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 mode
  23. Up till now PET has survived undamaged and unwarped in my car, even in our recent very hot summers with Mediteranean weather, quite unusual for Belgium. Contrary to PLA that even did not survive a mild spring or autumn sun. I think PET can have around 80°C? If you would need it for autoclaving and desinfecting at 140°C, that would be a different story.
  24. Excellent info from p-kimberley above. What is said, is absolutely true: any layer lines, blobs or irregularities will show up in the cast, and they will make it *much* more difficult to remove the cast from the mould. I have made silicone moulds from 3D-printed models. It goes as follows: first 3D-print a model, including what will become the filling canals and venting holes. Print in multiple parts and assemble as required. Carefully remove all blobs and irregularities, and smooth the model, as any defects will show up. Stick the model to a plastic base plate, or provide some for
  25. Maybe you could do it with a trick? Put four tiny dots outside of each corner of your models. So that they form an imaginary rectangle that encloses your design. Or draw a custom skirt around your design; just one layer height is sufficient. Then that surrounding skirt or border should always be placed in the same position on an empty bed. Keep that skirt, or those four dots, in place, and then correctly place the rest of your components in this space, and save as separate files. When slicing, the skirt (or the four dots) should determine the position on the glass. At least, that is what I wou
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