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geert_2

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Everything posted by geert_2

  1. Can't Blender or FreeCad open and repair them? They are both freeware, so that might be worth a try?
  2. The steel wire version of the FilCatch won't melt or break. I have been using this now for a couple of weeks, and it works well. So this was a very simple but great idea.
  3. I tried this today, but it did not work well. What I feared did happen indeed: molten filament creeps up between the nozzle and silicone cover, and it breaks the silicone at the top (where the nozzle meets the aluminum fan mounts) and pours out there in a big blob. This is probably due to the silicone cover being flush with the nozzle, so it sort of pushes a bit on the surface while printing. When there is a little bit of overextrusion, as on the first layer or on short strokes with frequent stops, the melt choses the way of the least resistance, which seems to be in-between the nozzle and si
  4. Hmm, the first annealing test in the Ultimaker was not totally convincing. In the photo above, the flat object is freshly printed, the warped one is annealed. Both are the same PLA. While it was sitting in the "oven" (=under a cover on the ultimaker bed), I couldn't resist playing with the temperature, and I increased it to 80°C, so it came loose from the build plate and reverted to a more relaxed state. I should have left it at 55°C, I guess... Anyway, this shows how high the built-in stresses can be, even in "low shrink" PLA. And what you might get when you leave such a model in your car
  5. I have similar font weirdnesses as Daid describes, although not identical. It looks a bit like the font is drunk. Also the fonts in the title bar (Explore Products Stories etc...) look pixelated. OS: Windows 7 SP1 Browser: Pale Moon (most recent version). Pale Moon is a split off of Firefox which still uses the old-style layout with menu bars and status bars.
  6. Yes indeed, I hadn't thought of that. If the spray can totally consists of polypropylene or polyethylene, it will survive. But if it contains ABS parts, you would indeed have a real problem when spraying acetone...
  7. I only wipe the glass plate with salt water prior to printing. For PLA, this gives a very strong bonding when hot, but no bonding at all when the glass is cold (so you need a heated bed). For a full description and photos, see the PDF manual at: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/# For colorFabb and Ultimaker PLA this works excellent: I could print anything without corners lifting, except upside-down prisms and pyramids. No brim or raft are required. I have printed more than 500 parts in this way without failure (except those inverted prisms as test parts). Howev
  8. I tried printing a few threads before, but they didn't work well, and I had to cut them anyway afterwards. So now I just design round holes and cut threads afterwards. You sometimes find complete thread cutting sets for 20 euro in the Aldi (in Europe). Just be very carefull when cutting threads in PLA: it heats up so fast that the model deforms and the thread gets liquid. So that would be another option to make a thread: take an M12 inbus screw and force it into the opening, so it *melts* the material into shape.
  9. I don't know the G-codes, but I had this too a couple of times. I don't know why. After loading the model again in Cura and saving it again, this problem vanished. A bug? When comparing G-codes of a good and bad model (from the same STL-file), there were indeed a few extra lines of G-code in the bad one. After removing them, it went all right too. But I don't remember which codes I removed.
  10. Isn't your PLA already destroyed beyond being usefull at 130°C? At that temp, my PLA is usually shrinking into a ball or leaking away... And what if your customers would use alcohols or etox to sterilise things? (Although I wouldn't recommend using etox: it is highly explosive, causes severe chemical burns, and causes cancer.)
  11. In its simplest form, the "box" around the model would be a simple standard food box, as in the photo. Or two on top of each other, for a better insulation. Just put it over the print at the moment it finishes, adjust build plate temp manually to the desired level, let it sit there for a couple of hours, and then very slowly let it cool down. Maybe I forgot to stress this point in the previous posts: after annealing, let the prints cool down *very gradually and very slowly*, preferably over a period of a few hours. Don't remove the cover before it has totally cooled down to room temp. So th
  12. Here are a few pictures: one is from a very small transparant block (about 0.5cm), with a small metal ball from a bearing pushing on it: you see the stress distribution due to this load. The other photo is from a moulded part in Araldite two-component resin, containing a lot of bubbles due to the mixing. You see the stress concentrations around each bubble. And the last shows the moulded in stresses in a dental appliance, especially around the metal pins. The higher the stress concentration, the closer the coloured lines are sitting together. This is a bit like height-lines on a map (I
  13. I also have this on small parts, for example on fine text of a few mm height. It indeed seems to be caused by the head stopping for a fraction of a second while retracting, and then moving on. I can reduce it but not eliminate it by reducing temperature and printing slower, for PLA down to 180°C or 190°C, and 20mm/s, for small parts.
  14. The idea is not to reduce warping while printing, but to reduce internal stresses that would cause problems later on during the part's service life. A bit more about the background: when any parts are moulded in metal, glass or plastic (for example via injection moulding), they have huge amounts of internal stress moulded in due to the force of the flow that was used, and due to the always uneven cooling that follows. Edges and thin areas cool faster than the inner parts and big volumes. If you watch transparant parts of glass or plastic under polarised light, you will see al those nice colo
  15. In another post user Artiz mentions as a side note that he anneals his polycarbonate prints by moving the glass plate directly from the printer into an oven, and let it sit there at elevated temperature for a couple of hours, to relieve the stress due to uneven cooling caused by the printing process. This seems like a very good idea. The advantage of doing this on the glass plate, immediately after printing (thus without the glass cooling down) is that the models do not warp as long as they sticks well to the glass. I have done annealing in an oven too, but only after removing the parts. In
  16. If you *tune* the speed up to 150%, then you not only increase printing speed, but also traveling speed (which is usually much higher than printing speed). If traveling speed would for example have been set to 200mm/s, then that would become 300mm/s after tuning, which might be higher than the maximum the stepper motors can handle without skipping. Could that be the cause? When playing around with tuning speed up very high, just to see what would happen to my extrusion, I experienced something similar. I would suggest you try setting the printing speed at a desired high value in Cura (or wha
  17. Since about 10 days I wipe the nozzle with non-stick silicon oil prior to printing, and then again after each print. I use the sort of silicon oil that is also used for easier release of castings from a mould. Since then I have no more build-up of molten material under the nozzle. Maybe you could try that? First clean the nozzle's outside thoroughly: warm it up a bit (to 120°C or 150°C or so) and wipe it clean with a tissue. Then spray silicone oil on a small paper tissue (but do this far away from the printer, so that you get no oil on the build platform, which would destroy sticking). And w
  18. Do you make them on a vacuum thermoforming machine where the model and the plate to thermoform are both placed under a heater, and the hot molten plate is then pulled over the dental model, and sucked vacuum? (Such as the Erkodent thermoforming machines?) In that case, probably the heat is the main problem. PLA starts getting soft from around 50°C, and your thermoforming plate is heaten to maybe 120 or 150°C or so. So I would suggest that you try printing the teethmodel with 100% infill, just for testing, and that you put that model in the freezer prior to thermoforming. Do not yet insert
  19. I see that you print with 2mm filament? I guess by that you mean: "2.00mm", is that correct? could you check that again? Normally, the filament should be 2.85mm (which is sometimes referred to as "3mm filament"). So, if you use 2.00mm filament indeed, you will sure get underextrusion, since the printer expects a much thicker filament. The surface area of 2.85mm filament is about twice that of 2.00mm filament. So you need to accurately measure the filament diameter and set this correctly in the settings (but I don't know where to find that setting), or you need to adjust flow rate accordingly
  20. I never use the official method to change filament. It goes much easier in this way: - Remove the horseshoe clip on the head, and remove the bowden tube from the head, with the filament still in it. Since the Ultimaker2 does a large retract after each print, this goes easy. - Move the material 1 cm forward, and cut off that irregular molten end. This eliminates the risk of getting that irregular blob stuck in the feeder, or getting the thin string in the feeder. - Do an atomic pull to remove the remains of old material from the nozzle, and to clean it at the same time. Do more atomic pulls
  21. The software seems to be their own development. The basic idea is brilliant, definitely worth remembering. But at this moment the distortion seems to be too much concentrated in a few small areas. If the distortion was more equally distributed over a much larger area, this would greatly improve component life, I think.
  22. I used to say that 3D-printing was not accurate enough to create smooth dolls like barby dolls or so. But obviously I need to revise that statement. Then a question: instead of using a brush, have you ever tried using a spray bottle? The sort of bottle with a hand pump, and adjustable spray nozzle, which people also use to spray plants? If the spray could be adjusted fine enough in a fine mist, without big drops and pooling, then you wouldn't need to touch the model while spraying. So you have less risk of getting marks on the model. Or would that have other side-effects?
  23. As Didier says. I also had this once when the 230V power cable came loose from the power supply. After that I made a clamp from steel wire, so that the power cable can never detach by itself. Never happened again. Also, on the Ultimaker2 (I don't know about the plus), the little power connector at the back of the printer needs to *click* into place. Otherwise it is not inserted deep enough. I would check these first.
  24. If you would ever have an issue with PLA not sticking well to the glass plate, try my "salt method" first: dissolve some table salt (NaCl) in water, and use that to wipe the glass plate. Let it dry into a thin mist of salt stuck to the glass. This gives an excellent bonding when hot (60°C), and no bonding at all when cold (20°C). Salt and water cost you nothing. - For Ultimaker and colorFabb PLA: excellent bonding, no corners lifting at all, no need to use brims or whatever. - For ICE-PLA: still good bonding, but not perfect: occasionally corners of difficult objects (big, 100% filled) do li
  25. Does it need to be 3D-printed? Another option might be to print a negative in 3D, thus a mould, carefully sand that so it has a perfect shape, and then use that to cast the models in any appropriate material? For example polyurethane? This comes in a lot of different qualities, from hard, to tough but still hard, to very flexible. If it needs to be stiffer, or reflective, you could add in filler particles, such as metal. If you need a lot of copies, this might be the fastest way? In Youtube, search for: mould making and casting, to get an idea.
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