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Everything posted by geert_2

  1. I also have this on overhangs. It seems to come from edges of overhangs curling upwards, and then being pushed down irregularly when the next layer is printed. Printing cooler helps, but does not totally cure it. What also helps, is placing a fan in front of the printer, or blowing with a gentle stream of compressed air on the affected parts (especially for very small parts, not practical for large parts). Sometimes you can go down to 190°C at default speed of 50mm/s for PLA, depending on PLA brand, color, state of the rest of your machine (eg. teflon coupler), and the friction or unwinding
  2. Nylon is known for being very difficult to glue and paint. You will definitely need a chemical activator. This makes the surface chemically active and able to chemically bind to other stuff like glue and paint. Otherwise, it won't work. (Nylon can be colored in the mass by soaking it in colored water, but that is probably not what you want here.) I have no idea where to find activators, or which brands. I think you would best contact service-engineers of big nylon suppliers, like BASF or Bayer. Or search their sites for info. These big companies do deliver nylon pellets to all plastic parts
  3. If your design has some hidden areas which can not be seen (or which do not matter), then maybe you could try designing a sort of "zip-fastener" into it? One zip in PLA, the other in PVA? So that the PLA and PVA alternately hook into each other, and they mechanically grab and keep each other in place? I don't have an UM3, so I don't know if this would work. Might be worth trying?
  4. Forgot to mention in my earlier post about silicone socks: another important thing with a silicone sock is that it may have a high friction (like most silicones), and it may rub off the first layer from the glass. Otherwise, using a strong adhesive silicone like Tec-7 might have been an option. Concerning PTFE, I have tried PTFE oil from a spray can. Sprayed it on a tissue, and then wiped the nozzle. But that doesn't get baked on, and it does not stick to the nozzle. It actually gave worse results than wiping the nozzle with a tissue with silicone oil. I have no idea what baked-on PTFE would
  5. Which version of SketchUp are you using? I should have mentioned it, but I was talking about the freeware version Google SketchUp 8.0 (the latest freeware I think?), with which I had bad experiences for 3D-printing. But of course it may have been improved in the professional versions after it was taken over by another company. Google bought it for designing surface-3D-models of buildings, for its Google Map and Earth projects. Watertight 3D-modeling for 3D-printing was not on their priority list back then. I don't know what the focus is of the new owners?
  6. The curling is greatly reduced - but not eliminated - by wiping the nozzle with silicon oil. The kind of oil that is also used for lubricating car door rubbers in winter, to prevent them from freezing up, and similar. I found it in a car shop. The filament still starts to curl, but since it sticks less to the nozzle due to the silicone oil, it tends to fall back down soon. For wiping I use a sort of quite strong paper tissue, as used in laboratories. I don't know the specs, since it is old, and I don't have references anymore. But any strong and rough paper tissue should do, I think.
  7. When saving as STL-file, do you have options for setting the units? If they would be set to mm now (and appear as meters), then you might try setting the units to meters for exporting? Otherwise you could try loading the STL-file in another STL-repair program (I don't know the names), verify it there, and save again? SketchUp is known for creating bad STL-files for 3D-printing. It was designed for creating visual 3D stuff only (houses etc.), no watertight 3D models.
  8. Question: if you tighten the screws "as hard as you can", then don't you destroy them? Or the hex tool? These small M3-things don't look very strong...
  9. I tried the silicone socks with pushing on liquid silicone in a spoon (see pics above), but since that did not work, I dropped the concept. Molten filament kept creeping in-between the nozzle and silicone, due to the pressure applied while extruding (especially when there is a little bit of overextrusion as on the first layers). The silicone was too flexible to prevent this. This molten material then perforated the silicone near the top, so that the melt spilled out at very undesired places. So I removed the silicone again, and now I keep the nozzle clean by wiping it with silicon oil prior
  10. Whatever your scanner choice, I would recommend that you go to a distributor nearby (or someone who has such a scanner, maybe search via 3D-hubs or so). Explain your wishes, and have them scan one of your typical items, and process it in front of your eyes (thus they can play no hidden tricks). So that you can see what the result is, and if it is usable. Pay for it if required. A distributor who has confidence in his equipment and who knows it works for you, will generally be very willing to do this, if it is likely to result in a sale. And he also gains more experience from it, which he can
  11. I usually design custom supports in my models, as these models are often complex or very small, and the standard supports of Cura don't work well in my case. I design both the models and supports in my CAD program DesignSpark Mechanical (freeware, a limited version of SpaceClaim). Slicing is done in Cura. For ideas on how to make the supports, see this thread: https://ultimaker.com/en/community/34784-best-settings-for-support-structures
  12. If you print on blue tape, the print might stay stuck to the plate. Might, not sure. If you print PLA on bare glass, it will come loose when you stop heating the build plate. If you use my "salt method" (=gently wipe the glass plate with salt water prior to printing PLA) then the print will stick like glue when the plate is hot: 60°C. But there will be absolutely no bonding at all when the plate is at room temp.
  13. As Robert says, try leveling the bed a bit closer to the nozzle. In my experience that helps a lot. Disadvantage is that you get a little bit of "elephant feet". Additionally, to improve bonding, you might also try my "salt method": wipe the build plate with a tissue moistened with salt water prior to printing, so that the glass is covered with a very thin mist of salt, almost invisible. For the full description and photos, see: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ For me this gives a very strong bonding when the glass is hot (60°C), but no bonding at all after coo
  14. I hadn't noticed the date either, haha. It appears in addition to being completely banner-blind, I am now getting "date-blind" too. I guess this revival of old threads is a side effect of entering forums via Google. Anyway, it may benefit others. Or even myself in a year or so, after I have long forgotten all my own good design rules...
  15. Instead of my previous reply, now to really answer your question. I think you are facing two problems: 1) First you need to design your thread within the tolerances according to the ISO-standards. On this site, you can find a "metric thread size and tolerance calculator": http://www.amesweb.info/Screws/IsoMetricScrewThread.aspx Here you can select the desired thread (e.g. M4), and the site calculates all tolerances such as min and max diameters, etc. Or Google for: tolerances in metric thread design This subject seems to be quite complex, way too complex for me anyway. And to furthe
  16. Hello Robert, You did not mention the purpose of the thread: does it absolutely have to be a 3D-printed thread? Or must it be a connection that can be disassembled? And would using standard nuts and bolts also be acceptable? I tried designing threads too, but due to the inaccuracies and tolerances in the printing process, I gave up. I had to post-process each thread with thread-cutting tools anyway to remove all blobs, strings, hairs,..., and to make it fit. Thread cutting in PLA is quite difficult due to the low glass transition temp. The threads tended to melt, after which I could not
  17. @neotko: your observation that it is "not a single line, but doing a line and coming back" on a 0.5mm support is correct indeed. I have also noticed it. But it seems to be not a "full width" line. Probably with a lesser flow, to arrive at an estimated width of 0.5mm? Maybe one of the developers could tell how it is done exactly? I use Cura 14.09, it may be different in other versions. The advantage is that these 0.5mm double lines give a bit more strength than a single 0.4mm line support. And it guarantees that the support will always be printed, even if the STL is slightly inaccurate. So
  18. That "recognising problem" is why I make my supports 0.5mm thick, to print with a 0.4mm nozzle. Indeed, if designed exactly 0.4mm, some supports may not be seen by Cura. I am not sure, but my guess is that it may have to do with the STL file: due to the STL-triangles instead of exact shapes of the original model, dimensions may get just a little bit smaller than 0.4mm. And then Cura won't print them (at least not my version 4.09).
  19. Have you tried a different SD-card? Or try formatting the card? Or try loading the STL-file in Cura again, and save it again on the SD-card? I have no idea what the problem is, but from your description and the image it looks like the printer can read part of the gcode-file (which means the printer itself is not dead), but it then gets stuck halfway reading the file. So I would first search in that direction: defectieve SD-card (hardware), corrupt files or FAT-tables on the SD-card (software), bad connections,...
  20. Similar to the image shown by GR5, usually I design all supports manually, and I optimise them for easy removal, good stability, and maximum accuracy of the model to print. In reply to a similar question, I posted a few pics of support concepts that work well for me. See: https://ultimaker.com/en/community/34784-best-settings-for-support-structures
  21. Something I just learned while watching Youtube videos on 3D-printing. So I thought I would just let you know. I haven't seen this mentioned here. When you begin printing with a new filament that you don't know yet, it might be a good idea to remove the bowden tube, and feed a bit of filament trough the feeder manually. Usually you will be doing an atomic pull anyway when switching filaments, so this is a good time. Manually set the nozzle temp to the lower end of the indicated temp range for that filament. And gently (!) push through some filament. See how well it goes. Also manually do a r
  22. I again tried annealing (post curing) a few items in the UM2 printer. These models are very prone to warping due to their long shape and 100% infill, with high internal forces. They also have sharp corners and indents at the bottom (invisible in these pictures) that makes bonding to the glass plate way more difficult than in models with a flat bottom. Annealing was done directly in the Ultimaker2 printer, immediately after printing, so the printer was used as an oven. Annealing or post-curing these models seemed to increase their temp resistance by about 10°C, and it reduces warping when exp
  23. Het kan automatisch in Cura (de precieze knopjes weet ik niet van buiten). Maar dikwijls kan je die supports beter manueel maken in je design programma. Tenminste, als je de modellen zelf kan maken en/of bewerken. De automatiekjes kunnen immers geen rekening houden met de soms zeer specifieke wensen of omstandigheden van modellen. Zie dit topic waar ik zojuist wat uitleg en een paar beelden met suggesties gepost heb: https://ultimaker.com/en/community/34784-best-settings-for-support-structures
  24. Here are a few pics of support-concepts that do work well for my designs. These are just things I learned the hard way; I am in no way a "support design specialist". In all these pics, the ribs on top of the supports are 0.5mm wide, and the horizontal gaps between the ribs are 1.0mm. Usually the vertical gap between ribs and the bottom layer of the model above the support is 0.2mm. Pictures: Bottom left: floating supports: each solid layer and each gap are 0.5mm high. The bottom layer of the supports is sitting on the glass plate, to create a good stable base. The other supports are just
  25. Hello again, I have tried smaller gaps than 0.2mm too, but that did not work well with my filament (Ultimaker PLA and colorFabb PLA/PHA) and my models. If the gap is too narrow, the bottom layer of the model sticks too hard to the support. When trying to remove it, this severely damaged the bottom layer of my models. With a gap of 0.2mm or 0.3mm, and the ribs rotated 90° as shown (very important), this gave the best balance between an acceptable bottom layer, and ease of removal of the support. At least for my relatively small models. For bigger models, I might try a bigger gap of 0.4
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