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geert_2

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Everything posted by geert_2

  1. If the automatic functions don't work well for your particular situation, you can design your own supports in CAD, so they become part of the model. Then you can implement anything you want: holes to insert hooks and pliers for better removal, gaps, ribs, hanging supports,... I only have single nozzle printers (UM2), so my supports are in the same material as the model. But for dual nozzle machines, you could design for separate materials. A few concepts I have used or considered in the past:
  2. Making a fine print from the original gcode, and then sand, smooth and paint that. And then 3D-scan and digitize that 3D-model? Would that be an option? Then at least you have a nice original to start from. But even when people leave a company in bad terms, you might be able to get them to cooperate, if you were not personally involved in the conflict too much. Most people can make that distinction. Also, doing a thorough search on STL, OBJ, and whatever else files on servers and local computers might give some results. Do this from a bootable stick, so you get around W
  3. You can always design (one of) them in CAD, and consider it part of your model. But for printing, using both has no practical meaning as far as I know.
  4. These too thin horizontal areas are underextrusion. This basically means that the printer can not deliver enough filament, for whatever reason: too much friction in the feeding traject, (partially) blocked nozzle, dirty feeder, filament windings under other windings on spool, worn-out teflon coupler, non-working little cooling fan for nozzle, nozzle too cold, flow too high, worn-out or incorrectly installed bowden tube,... There is a video and extensive list of possible causes somewhere on this forum, but I don't know exactly where. Maybe you can find it? The vertical l
  5. I do not have a dual nozzle printer, so no personal experience. But I do vaguely remember that supports might be printed at double layer-height, or beginning from a thicker minimum, or something like that, since it does not melt so nice as PLA. So, if the PVA would print at 0.2mm layers, and PLA at 0.1, you might get this effect. Could be an explanation. But I am not sure, it is just a vague memory, you need to check. Maybe you could search for this and find more info?
  6. If you bend PLA and then keep it bent under stress, then microcracks may grow, and they may keep growing until it snaps. This can happen when it is sitting in the feeding traject for a longer time. So it is best to unload it after printing, and store it under no load. As it gets older, it can become harder and brittle too. Moisture also degrades PLA, it breaks down the molecules, so that could also speed up the brittling-effect. But I haven't had it snapping while printing or while in the feeding traject yet. So, in your case, it could be a bad batch or bad brand too. Wood, stone, carbon, or m
  7. Yes, you should definitely print cooler. On my UM2 the standard for PLA is 210°C, but for tiny models printed slowly and in thin layers, I can go down to 190°C. On a test piece, while printing, try going down manually in steps of 5°C, and see what happens. At some point it will start to underextrude severely. Then go up a little bit until it flows well again. Then try that value for a whole tiny model.
  8. When selecting silent fans, keep in mind that they usually have a *much lower* flow rate and cooling capacity. So you might need to provide a lot more or a lot bigger fans. And indeed, adding rubber dampers, mats, or washers between fan and housing, can greatly reduce transmitted noise and resonant vibrations. Also adding a sound-absorbing mat on the opposite sides of a printer (or room) might help: this does not eliminate the source of course, but it damps the reflections and resonance. Similar to the covering of walls in a sound studio, but then in miniature. If your printer desi
  9. And what is the effect if you make the wall thicker? (Or thinner, to exaggerate the effect?) I also have noticed that any sudden changes in layer-area to print, or in wall thickness, do show up as horizontal lines. Try this on a small cut-out of your model, at the place where the problem appears. So you don't waste too much time and material.
  10. Like gr5 said: this is a cooling problem: the hot nozzle keeps sitting on same spot on top of the model, so it can't cool down and solidify. This is a limitation of this printing-concept. I often print small models that have this problem. Then I print multiple at once, so one can cool while the other is printing. Or I print a dummy tower next to the real model. Ideally, the dummy should have the complementary surface area as the real model, so that the total area per layer is constant. Brutal changes in layer area show up as horizontal lines on small models. Printing sl
  11. @thorsenrune: I don't know what this "@-thing" does, other than drawing visual attention, so I rarely use it. :-) And yes, you can quote me on the Onshape phylosophy. I am used to very wel organised graphic design packages, with easy navigating through logical menus and toolbars. Functions should be where you expect them to be. But in Onshape all functions seem to be randomly splattered all over the screen, and often hidden, without any logic (or at least I can't find it). I had to consult the manual *every time*, again and again, even for the simplest functions like saving or expo
  12. I have tried Onshape, in the beginning when you could still have 10 private models (all above 10 would become public, accessible to the whole world). But I don't think you can still have 10 private models? Maybe 4? Unless you pay big money per month. Anyway, I could not find my way around in its user-interface: I can't find anything and can't get anything done. Its phylosophy seems to be incompatible with mine, so I stopped using it. This could be my problem of course, since some other people *can* make great designs in Onshape. :-) I have a very different graphics background tha
  13. In my experience, *random* crashes usually indicate a hardware problem. Often memory modules that got defect, or contact pins that got dirty or oxidated. If the driver update would not help, and if you can access the memory modules, try gently (!) wiggling them a couple of times. This has often worked well in my PCs (I don't know for a Mac). Maybe try a night-long RAM memory test? Memory-problems often show up only on memory-intensive software that occupies nearly all of the RAM: 3D-software, browsers with a ton of open tabs all playing videos, etc.
  14. To me your samples look pretty decent. This is what I would expect. Infill is not meant to be visually perfect: its purpose is to add strength in *invisible* areas. And to reduce material consumption and printing time in invisible insides, where a solid body is not required. So its purpose is a good balance between strength, printing time, and material use. Although today there are a couple of really beautifull infills indeed. If you want nice looking spokes, and you want more control over how they look, I would suggest you design them in CAD. See the model
  15. On my UM2, the tube is also worn-out, but it keeps clamping well. If the nozzle is not blocked, and there are no temperature problems (printing too cold, so it does not melt), the tubing is the correct diameter, and the filament is not too thick, or any other things that block feeding, then I keep thinking that you might not be inserting the tube well enough? It is not sufficient to just push-in the tube all the way down. At the same time, you also need to lift the white ring as high as possible by pulling hard: this lifting is what will cause the locking afterwards. Could you veri
  16. For the future, get your staff and students to use other software than SketchUp for 3D-printing, or you will keep running into problems and keep repairing errors. SketchUp was designed for visual models only, not for 3D-printing. It produces sort of "cardboard" models where the edges do not fit together and are not watertight, not solid. It is excellent if you want a quick idea on-screen for an architectural concept, as long as you are not going to print it. Students and educators can often get free or cheap educational versions of professional 3D-CAD software. Otherwis
  17. I wonder how this would reduce stress? Wouldn't most of the stress be caused by adding hot new layers to a colder base, causing an *upwards* pulling force due to shrinking? Further, I think this might cause more ugly corners: now the ringing effects are on only one side of a corner, and they are the same for each layer. When alternating, these effects would alternate too. This might cause the same combing effects as on interlaced videos?
  18. I just printed a filter for my vacuum pump, to prevent it from sucking up big particles when suddenly applying vacuum. The filter was printed on an UM2, thus in a single material, no supports. I printed the first model at 0.3mm layer height, 25mm/s. This was *not* airtight: when I put tap water on it, maybe 10 tiny jets spurted out of the shell, through tiny holes. The holes were where the layer-changes and take-offs and landings from traveling had occured. The second model was printed at 0.06mm layer height, and 50mm/s. This model is *absolutely watertight*. Yes it too
  19. I think the basic idea is excellent, and worth trying out. But maybe an optical sensor or mechanical switch might be more reliable? I would fear that a thermal switch could cause false alarms, e.g. when printing hot and slow without cooling fan, so there is no airflow. Then it might get too hot and trip. Or it might miss real leaks when printing fast, cool and with full cooling fan, if the air blows directly on the sensor, and it cools the outer shell of the leaking plastic too fast. Such a sensor should never give false alarms and abort a good print, nor miss real events: that will be the mos
  20. I never used sprays for 3D-print adhesion. But years ago I did use a lot of silicone anti-stick sprays for moulding and casting models. I had built a special cardboard box with fume extraction at the back, to take away the spray mist. And I only sprayed deep into that box. But even then the whole area outside of that cardboard box got slippery with silicone oil too, after some time. I have seen similar setups where people used spray paints, and there too the whole environment got colored. Even though they had fume extraction in their cardboard box, just like me!
  21. If it is a lab with normal ventilation, and you did not sit with your nose directly above the printer all day, and if you only printed PET or PLA, it probably will not have done any damage. Seems very unlikely to me. I don't know where you live, but here in Belgium the laws require that the air in a lab is renewed several times per hour (was it 6x or 10x? I don't remember). So you should get plenty of fresh air in the lab anyway. In a research lab, most other products you use will probably be more dangerous: solvents, biochemicals, composites,... Things woul
  22. Steep overhangs tend to curl up. Maybe that might cause this deformation? Watch closely while it is printing, then you can see if this is the cause indeed. If you can't get it to print well, another thing you could do is make an undeep thread, so the overhangs are not so steep. And then using a standard thread cutter, cut the final thread. When cutting threads in PLA, go very slow, and with lots of cooling. Otherwise everything will just melt. Don't ask how I know... :-)
  23. I have silica gel with a moisture indicator, which turns from dark blue when dry, into pink when moist. To the Ultimaker-developers: maybe you could try adding this moisture-sensitive pigment to the PVA? Then people can see at a glance if their PVA is still dry enough? I don't need it, since I only have single nozzle UM2-printers. But moist PVA seems to come up again and again here on the forums.
  24. I didn't make a real font-file, since I don't know how to do that. So to set text, you need to copy and pasted each character from the character set, letter by letter. Like in the old days of metal printing. This is good for a short copyright notice, but not very suitable for 3D-printed newspapers, obviously. The character set is in DesignSpark Mechanical's native format, RSDOC; and DesignSpark Mechanical is freeware (requires registration). If you would like to convert these characters to a real font, thus a TTF-file or similar, feel free to do so. Just kee
  25. When mounting the bowden tube, do you push it far enough in, all the way down? Thus: first lift the rentention ring with your finger nails. In my printer this is a white ring on top of the head, where the tube goes in. Then insert the bowden tube all the way down, while you keep the white ring lifted. And then insert the horseshoe clip? If the tube is not inserted deep enough, it may not grip well upon pulling. That could produce the phenomena you see. (But that does not mean there can't be other causes, such as a worn-out tube, or incorrect outer diameter.) For easier
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