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geert_2

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Everything posted by geert_2

  1. A couple more pics: Untreated Smoothed, but overdone: see the dull area near the top When overdoing, the holes shine through the bottom, indicating that dichloromethane penetrates quite deep into the plastic and keeps melting/dissolving it. These indents take some time to form. Untreated text: this text is ca. 7mm high Smoothed: it looks out of focus, but it isn't (the dust is sharp) Untreated, close-up Smoothed, close-up: notice the bubbles oozing out of the edge of the hole
  2. Here are a few photos of before and after smoothing with dichloromethane. Filament under test is only colorFabb PLA/PHA for now, because I have lots of old waste parts available for testing. Nozzle-size is always 0.4mm. Layer-heigts may vary between 0.1mm and 0.3mm (I don't remember for most parts, too old). Most parts are quite small, often ca. 10mm wide. All tests were done by brushing-on. I haven't tried vapour-smoothing yet. Smoothing still continues a bit after the dichloromethane has evaporated, while the PLA is drying. So you need to stop a bit early. Similar to
  3. A print speed of 40mm/s seems quite fast to me, for such a big nozzle and layer? If I had to print it, I think I would rather go for 25...30mm/s. At least, that is my experience with PET: print as cool as possible, well below decomposition temperature, and then print slow and in thin layers to give it enough time to melt and bond well to the previous layers, and to cause not to much ringing-effects due to speed. These below were a couple of tests with PET. Top row speed: 50mm/s. Bottom row speed: 10mm/s Layer-height from left to right (mm): 0.4, 0.
  4. Edit: Quick summary: dichloromethane (=also known as methylene chloride), formula C H2 Cl2, can be used to smooth the surface of PLA and PET, in order to remove or reduce layer lines, and seal tiny openings in-between the printed sausages, or seal mild underextrusion. Dichloromethane can also be used to bond PLA and PET. Also see the Wikipedia info: https://en.wikipedia.org/wiki/Dichloromethane Below you find a lot of photos of the smoothing-effect on PLA and PET, and of the bonding. ----- I just received a bottle of dichloromethane and did
  5. I have been printing PET or PETG (I don't know for sure which one) quite regularly on my UM2 (non-plus). Whether this is officially supported, I don't know, but it works. Don't print on bare glass, use some sort of glue instead. Otherwise the print may eat chips out of the glass upon removing. A disadvantage of PET is that it tends to leave burnt residu in the nozzle: a sort of glossy black varnish, which is more difficult to remove than the black powder residu from PLA. At least the sort of PET that I have (brand: ICE). For best results, I need to print slower than PLA
  6. You can make it a lot easier to remove/replace the bowden tube by printing a couple of these clips. They are much easier to handle than the standard pneumatic clips. Pull it out, push the white ring down, and pull out the tube. Replace in opposite way: push tube down while lifting the ring, then insert the clip. See here for the files (and then scroll down): https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
  7. I don't know about current Cura-versions, but on older versions special characters could make files invisible to the printer. So indeed the above is very good advice: use only short filenames, only lower case letters a...z, numbers 0...9, and underscores or minus-signs. Nothing else. Definitely no spaces: they go broke in URLs and across some operating systems, and in batch-programs (batch copying or backups). No special characters, i.e. no: * / \ & | ? : + = " @ etcetera, as they are often interpreted as commands by operating systems, instead of as character. No foreign langua
  8. I haven't used ABS myself, but I read it can tend to clog the nozzle after some time, because its melting temp is close to its decomposing/burning temp? Have you cleaned the nozzle? Maybe printing a bit slower and cooler could help? If you suspect the bearings anyway (I don't know your printer), then try a small test-cube first, so you don't waste too much plastic and time on a complete big model. And see if it is present there too. If not, it's not the bearings probably.
  9. Tiny holes (e.g. <1mm) tend to get filled up because the molten filament is pulled inwards into the curve, like when you try to pull a rubber band into a circle. But most likely your model is defective, and has unwanted surfaces on top and bottom? So you might need to correct that in Blender, or run the STL through a repair-program. But I have no experience with this, so I can't give recommendations. When designing in DesignSpark Mechanical, I never had such problems, it always produced good STL files.
  10. I am not sure what the zits are, but it could be seam lines where the nozzle begins/ends a loop, and switches to the next? I never played with retraction settings, so I can't comment on that. But usually, printing slow, cool and in *very thin layers* improves quality. The "slow and cool" you already seem to have, but try 0.06mm layer height?
  11. If regular cleaning would fail, and you are going to drill out the nozzle anyway: maybe consider making your own drill from a 3mm copper or brass rod, or a brass M3 threaded rod? Brass is less hard than steel drills, and thus far less likely to damage the nozzle internally. Ideally, give the tip of your self-made drill the same shape as the internals of the nozzle-tip. So your custom drill should be softer than the nozzle-internals, but harder than the plastic you want to remove. (Maybe this would be a good tool to provide standardly with all printers?) I sometimes use
  12. I don't know that printer, but just a thought: if it is a self-built machine, couldn't it be that the end-switches (=the ones that should activate when homing the head) are mounted or wired incorrectly? So that they do not give contact? Or way too late? That would also cause it to keep going.
  13. In addition to what thinkergnome said: do *not* design it in SketchUp, as this creates exactly the problems you have now. And probably also not in Blender, as this also occasionally seems to cause problems, but less than SketchUp, and it is way more powerfull (also way more complex). Another program you could use is DesignSpark Mechanical (freeware, requires registration). I never had any such problems in many hundreds of designs. If you have to redesign from scratch anyway, see if you can replace the thread with a plain hole, and a bolt and nut, or similar standard har
  14. Wow, all those bricks and details did come out really well. I hadn't thought it could look that detailed.
  15. I already said it in another post, but I don't remember which one, so I can't immediately find it... Some time ago I printed a filter for use in a vacuum pump, to prevent ingestion of pieces. I tested watertightness by putting tap water under pressure (8-9 bar) on it. If I remember well, it had a single outer shell, thus one pass of the nozzle. Printed at 0.3mm layer height it was not watertight: lots of small jets squirted out. But at 0.06 mm, printed slow and cool, it was absolutely watertight. If required, chemical smoothing such as acetone smoothing on A
  16. First check if that random movement is not in the layer preview in Cura. Most likely not, but there could be model problems or software bugs too. If okay, indeed clean the SC-card slot as Torgeir says: human hairs (I had that once), dust and filament hairs can get into it, causing poor contacts. If you have compressed air, blow it out. Or try a new SD-card. Try to write a long video to the old card, until full, and see if that plays well. Or run a disk check program on it. Something else I just come to think about: nylon can absorb too much moisture from the air in a few hours, deg
  17. I have no solution, but after it is completed, could you make a few photos? Curious what that marble looks like...
  18. I have heard about spontaneous unwinding of spools, especially near the end where they are tightly wound-up. Stiff filament acts as a quite strong spring, trying to wind up again. But if there is some sideways twist or rotation force present in the filament, it may jump off sideways. Indeed, anti-unwinding clamps are a good idea.
  19. In winter it might work, in summer I doubt it. And not if in direct sunlight behind a window. Standard PLA will for sure deform in a car left in the sun, even in mild spring or autumn weather. (Don't ask how I know this... :-) So if tough PLA is similar, then that will happen too. Also think about where the lamps will be: on a ceiling is hotter than on the floor, and above a radiator could be quite hot too. Do a few tests, and try them in the worst places, and then add enough margin.
  20. Exactly: print as slow, cool, and thin layers as possible. And, depending on the model, print multiple items at once, so the hot nozzle is moved away and the parts have time too cool down and solidify. Otherwise they stay molten. For more complex models, I also print a dummy tower (with inverted shape) next to the real model, for this cooling, and to make the printing time equal for each layer. Big changes in printing area do produce horizontal lines, due to differences in cooling time. See these: Left: printed without dummy tower, right: with dummy tower. T
  21. On my UM2 (=non-plus) the clicking noise is when the feeder tries to feed more material than the nozzle can eject. This is a sort of protection against overloading, I don't know the official name. Not sure if that is still the same on an UM2+? So, could it be that you are printing too fast, too cold, or in too thick layers? Or a bit of all, so that the nozzle can't melt it in time? Try a small testpiece and print a bit slower, hotter, thinner layers (whatever you think might be the cause)? But apart from the poor layer bonding, it seems the gear
  22. The normal procedure is to print slow, in thin layers, rather cool (because of the thin layers and slow speed), and set all temperatures equal. But it looks like you already did that, so... Maybe check if it is visible in layer-view in Cura, but not in the model in CAD? To see whether it is a printer-issue or a software issue or model issue?
  23. When printing a filter in PLA, I used only one wall of 0.5mm, and very thin layers and slow speed, to get it water-tight. It is mostly the thin layers (0.06mm) and slow speed that does it. When printing at 0.3mm layer-heigth, I got lots of tiny waterjets squirting out, like from a very thin injection needle. But I would recommend multiple nozzle-diameter lines, at least two. But the parts are very likely to warp in the sun, if outdoors. And the material might gradually degrade due to moisture and UV-light, like most plastics. So I would also encapsulate the electronics
  24. For PET, I need to heat the glass bed up to 80...90°C, for best bonding. And turn fan off or very low if you do not have too big overhangs. (You can't turn it off with big overhangs, otherwise they don't print well: the string snaps and curls up into a ball, instead of making a bridge. At least with the PET that I have.) I also had PET tearing a part out of the glass once, when I was using glue. So now I don't use glue anymore, but I wipe the glass with a tissue moistened with salt water prior to printing. For PLA, this greatly increases bonding, but for PET it seems to slightly re
  25. Your idea of using breakaway as raft made me think of this: what about using breakaway to clamp parts down? Like in the picture below. If the design allows it and if it has a sort of flanges at the bottom, or other features that you can grab, maybe you could hold it down like this? I have never tried it, so I have no idea whether it would work or not. But at least, if the breakaway adheres well enough to the glass, it would prevent the nylon model from coming off and sliding around. So it should prevent spaghetti? Theoreticallly and hopefully... Maybe worth trying on a small testpa
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