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geert_2

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Everything posted by geert_2

  1. Thanks for the feedback. I only see it now, must have overlooked it before. With that amount of shrinking, it could be good for artwork, toys like model railroad stuff, and other models that don't need exact dimensions. But less suitable for rulers or tight-fitting technical parts. If you would have real models that you can show, I would also appreciate that. In green state, after sintering, and then after further post-processing (tumbling, sanding,...). If possible, also in close-up? Would be good to see the differences in material structure.
  2. For me, the salt method works very well for long, low, and 100% filled models like rulers, that take 1 to 3 hours to print. Thus for my typical models. I use it all the time, and almost never use any other method. It gives excellent bonding for PLA (may not work for any other materials), when the glass is 60°C. But no bonding at all below 25°C, so models come off by themself after cooling down. No need to remove the glass from the printer. I just drop a few drops of salt water on the glass, wipe it, and ready to go. That easy of use is the most attractive for me. However, narrow bu
  3. I read on the datasheets that Aquasys dissolves at 70°C-80°C: does that mean that this is the minimum temperature to make it dissolve, or is that just the optimal for the fastest results? How does it perform in cold or hand-warm water, thus below 45°C, for PLA? It would be good if you could some feedback on your experiences.
  4. If it are rods, then it should be the *outer rotating rods*, those with the belts. Because it is their wobbly rotation that causes the pattern (I think). Try measuring and calculating if the circumference of the pulley wheel and belt matches the distance between the spots? Visually guestimating, it could. Or you could make it more easy: using a marker, mark a spot on the pulley and on the belt, rotate the pulley, and each time it comes along the belt, then mark the belt as well on that same matching spot. After a few rotations, your belt should have marks with the exact same distan
  5. Hope you can read a bit of English. I can read German, but not write it. I use a standard thin injection needle, of which I cut the sharp tip off (that would damage the brass nozzle), and rounded the edges with sanding paper. It was a little bit too wide, 0.41mm, and did not go into the nozzle opening. So I had to grind the sides also until they were 0.39mm ... 0.40mm. And then very gently poke from the bottom upwards into the nozzle, and gently push and scrape. Do not use side-forces, so you do not deform the nozzle-opening. However, I never had a total blocking, only
  6. I don't know Fusion 360, nor your design and requirements, so it's hard to give good advice. But in general, if you have special support requirements, you can always design them in the CAD-model itself. Then you have full control. I often do this because my models are tiny, and the supports are hard to reach: there is no room to get in with a knife or plier. See the example below: these are self-hanging supports, and easy to remove. The slot where they are hanging in, is only 5mm wide. If printed in PET, I need the supports, otherwise it wouldn't bridge. If printed in P
  7. To repair: trying to bend the rods the other way round, doesn't seem like a good idea to me: chances are that it gets far worse. So I wouldn't do that. I would say: now that you know the most probable cause: if you can work around this by using a slightly thicker first layer, then try to live with it? To rule out the glass for sure as a cause, what you could try is: mark and measure the exact centers of the "dots" you see, from the edge of the glass. Then rotate the glass 180°, and do the test again. If the cause is the glass, then the pattern should have rotated also.
  8. Glad you are back. I already wondered what happened. Yes, I understand the frustration of losing abilities. But the good thing is that concerning art, you are still way above average. Most people would not be able to produce that at all, no matter how much time they got. Like I would never be able to compose a song, no matter how long I got.
  9. I don't know your filament, nor your printer and print-bed, so it is very hard to give advice on what bonding methods and preparations you could use. But the chemicals you are using, are toxic and cause cancer, especially xylene. Some of my previous collegues got cancer after using xylene carelessly for years, against all our safety-advice. So use them carefully in well ventilated rooms, and don't touch them. Preferably look for non-toxic stuff, or less toxic. I have glass beds, and most of the time I never clean them: I just wipe them with salt water, and go. For my PL
  10. Off-topic, how to get pictures right: There appear to be some bugs in the image-insertion module in the forum. Inserting and moving pictures around by dragging and dropping, does not seem to work well. To get pictures right, I need to do this: - Ffirst drag and drop them from Windows Explorer into the grey area at the bottom. Not in the message you are writing, but just below that window. Then they will be uploaded, but not yet included in the message. -Now position your cursor on the right place in your text, where you want the picture to appear. Preferably t
  11. It could be the glass: glass is never totally flat, it has bumps and pits. If you look through a car window, especially on older cars, and in curved areas of the window, you will see the lens-deformations caused by this unflatness. But it could also be the rods not being totally straight. If they would only be 0.025mm curved, almost nothing, that would show up as a 0.05mm difference in layer height, in a sort of sine-wave. Thus a full layer in fine settings. If both rods have it, you could get a pattern like yours. Maybe you can check if the repeating frequency is one full turn of
  12. Your first layer should probably look more like these:
  13. I just think about it: if you want to make moulds, it is a good idea to have a look at manuals of injection moulding too. These manuals explain very well how plastic behaves when casted. And which guidelines to follow in mould-design. Although intended for injection moulding, a lot of principles apply to any kind of moulding. Search for: injection moulding manual bayer basf. And maybe other companies: most manufacturers of plastic pellets do have such manuals, available for free, because they want customers to be satisfied with their plastics.
  14. A couple more smoothed compared to original 3D-prints. These are in translucent PET too. In real life the difference is even bigger, but it is hard to get on photo. The thumbscrew is standard nylon, M4 thread, 16mm wheel. Layer-heigth was 0.06mm.
  15. I don't think you can easily cast in HDPE or PET, that normally requires injection moulding. Most casting products are two-component epoxies, polyurethanes, polymethylmetacrylates (=PMMA, as in plexiglass and dental models), silicones, and similar. So they are often quite thin liquids, and then chemically cure into hard plastic or silicone. PMMA should be food-safe when fully cured, otherwise they couldn't use it for dental applications in the mouth. I don't know about fully cured PU. Most platinum-cured silicones are also food-safe, like in commercial baking moulds. The basic proc
  16. Maybe you could put them in a well controlled oven, at the glass-transition temperature, and put a heavy weight on them, so they get flat again? Let it sit for several hours, and then very gradually let it cool. Or heat-up the bed of your printer, and let it sit there for overnight, with a weight on top? And then very slowly cool down. They might get straight again? Your models are thin, so I don't think they would warp too much if you use the glue stick, 3Dlac, hairspray or something similar for bonding? Worth trying. If it fails, then at least you know. Otherwise, you have an add
  17. Also, shells are 100% filled, and the shell in the curved part is longer than in the straight, which could give a bit difference. But so much...? I think you would best print them at the same time, on the same bed, and 100% filled. So there are no differences in infill-pattern, and no differences in shell vs. infill, and no differences in speed, temp, extrusion-rate (or underextrusion), etc... Maybe scale it down to 50%, for a quick test, so you don't waste too much material?
  18. Yes, to me too your part looks big enough not to worry about layer-time. Except if you would have tiny features protruding from the top. I wrote that reply because you asked it. But it is more for very small items. Very often I have models with a tiny top surface of ca. 10mm x 10mm with very fine details (as in the blue thing above). And then it becomes a necessity. And even then I often give the dummy a very crude shape: just hollow below the top area, and filled as soon as the tiny features are reached. Just to get the nozzle away, let that cool, and keep the flow going steadily.
  19. Yes, but don't do the whole model yet. Do a small test part: let's say only one bulb, attached to a short stem. And that with different gap-variations. See which gap works best. Then you will lose the least amount of time and material.
  20. User MakersMuse on Youtube has designed a testpart with various tolerances, specially for this purpose. After printing, you can see which parts still move, and which not. Then you know what tolerances you need to apply in your own designs. Also, printing circumstances have a huge influence: printing hotter, will melt them more together. Thick layers will reduce accuracy, as well as printing fast. So, printing slow, cool and in thin layers should give best results. Theoretically...
  21. Dichloromethane works for PET as well, and it is even more agressive: in one generous brush-on application, it removed all layer lines in my tests. See the photos. The outer layer stays soft for quite a while. Sometimes it gets a bit milky, but that goes away with time, and/or can be wiped off the day after. Pro: much smoother surface, no layer lines anymore. And internal features such as watermarks in transparent/translucent PET become better visible. Contra: the tiny bubbles... And the fact that I have no idea about long-term effects: deformations, changes
  22. Not sure, but I think a gap of 0.5mm might be a little bit too big? Maybe make a small test piece with gaps of 0.1, 0.2, 0.3, 0.4, and 0.5mm. Print that and compare what works best for you? It will also depend on the material, cooling, printing speed, printing temp: obviously, hotter will melt things more together. It will also depend on the width of your support: wider will be more difficult to remove. I usually take "one nozzle-width" for such supports (thus 0.4 to 0.5mm wide for a 0.4mm nozzle): that is still easy to cut off. And gaps between 0.2 and 0.4mm, depending on the model. My fixed
  23. I think you will need to provide images of the models, of the cross sections, and of the layer-views while slicing, and project files and parameters. Otherwise it would just be wild guessing.
  24. If I had to print this model, I would consider one of two options: 1. Split the model in half, top and bottom, print both halves separately, and glue or bolt them together. In case of bolting, provide holes for inserting bolts and nuts. I often use standard nylon M4 for most of my designs that need to be assembled and disassembled. 2. Design a custom support and brim in CAD, so it fully supports your model where you want. If well done, it should print better, give less deformations. But it will cost time and may take a bit of trial and error. If you leave a tiny gap bet
  25. In my experience not. (But other people may see things differently of course.) Because then the nozzle is sitting there and just waiting. The flow is stopped, the filament spends time in the nozzle, heating up more, thus getting hotter than before and more liquid. It may ooze, and it will surely have different flow characteristics than before, which will show up as horizontal lines. Also, the heat accumulated in the filament, still has to "evaporate" after printing. Thus if it gets hotter due to waiting, then that extra heat also needs to get out of the print. The only advantage is
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