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Everything posted by geert_2

  1. For PLA I only use the "salt method": moisten a paper tissue with salt water and then gently wipe the build plate. Gently keep wiping while it dries. So there is a very thin and equal, but almost invisible mist of salt on it. But not too much. For colorFabb PLA/PHA and Ultimaker PLA this gives a very strong bonding when hot (60°C), and no bonding at all when finished and back at room temp. This makes removing the parts very easy, as it requires no force at all. For ICE PLA the salt method still works, but no longer perfect: corners do slightly lift sometimes. Fans can be full on, as required
  2. For hard filaments like PLA, I usually unwind a bit of filament, then wind it in the opposite direction agains a skate board wheel (7cm diameter). Just half a turn of filament, about 15cm. Then I release it, take the next 15 cm, wind in the opposite direction around the skater wheel, release, next 15cm, etc... This straightens the filament a lot. In two minutes I can straighten about 3 meters like this. Then I let it wind up again on the spool. But now it is sitting very loose, and the unwinding resistance is near zero. Also, the friction in the bowden tube and nozzle is now near zero. Apart f
  3. Yes, you are right. Bold does indeed work well for some "monoline fonts" where all strokes are the same width, typically road-sign style fonts, and if the characters are not too small. It is a good solution if you need text of ca. 10mm high. I have used that too. But for a lot of average fonts, bold mainly thickens the vertical strokes, not so much the horizontal. That still gives lots of problems in the narrow areas of characters like: a, r, n, b, d, etc., at very small sizes (a few mm caps-height). And it obviously doesn't work at all for serif-fonts. Maybe the reason why it is not said, i
  4. Yes, search seems to work much better now, I got accurate results.
  5. In the beginning, I also had trouble that Cura wouldn't print things smaller than 0.4mm (UM2 with standard 0.4mm nozzle). So for printing small text, I designed my own character set on a 0.5mm grid. Thus all strokes are wider than 0.4mm, with some spare: vertical and horizontal strokes are exactly 0.5mm wide. Diagonal strokes have a width between 0.48 and 0.53mm. Caps-height is 3.5mm, and most characters are 2.0mm wide (except W, M, and a few others). These characters are very easy to design, and they print reasonably well if printed cool and slow enough. I also tried different variants of s
  6. After cleaning, but before assembling it again, it might be a good idea to check tightness with compressed air and a gas pipe leak detector (spray can), or with water? Then you can see if there are still any leaks. I don't know if adding heat resistant copper paste on the threads is a good idea? or some similar anti-leak and anti-lock stuff? Like they do in chemical industry?
  7. 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
  8. 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
  9. 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?
  10. 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
  11. 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?
  12. 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.
  13. 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.
  14. 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...
  15. 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
  16. 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
  17. 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
  18. 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.
  19. 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
  20. 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...
  21. 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
  22. 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
  23. @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
  24. 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).
  25. 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,...
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