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geert_2

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Everything posted by geert_2

  1. I would say, try to minimise nozzle pressure and leaking by printing at the slowest possible speed, lowest temperature where you still get good flow, and thinnest layers. That should reduce the defects, or at least make them smaller, less visible and easier to remove. And then sanding and polishing... Could you show us a completed and post-processed ball? It looks like a nice design.
  2. In my UM2 the walls seem to be slightly rougher, but the corners seem to be a little bit cleaner, when printing at 45°, compared to the standard 0°. But hardly noticable, mainly on small features. I am not sure if that is due to the printer, or the slicer making different moves, or my imagination. Definitely not big enough to care about. I would say: just try it. Put them both on the same bed (so, same material, same external circumstances, same filament), but one 45° rotated, and watch carefully? Maybe add a few small details to three sides of each block (=on one side on each axis
  3. It looks like the effect is mainly on heights where there is a sudden big difference in surface area? Is that correct? In the past I noticed that when the surface area per layer changes abruptly, this causes visible horizontal lines, a bit similar to yours. But mainly in *small models* (I don't do much big models). So in my case it is most likely due to changes in cooling time per layer, I guess. Do you have the same printing speeds for all (inner and outer walls and infill)? If not, a sudden change of speed may cause fluctuations in nozzle temp and pressure, and that m
  4. As said above, the curling up appears to be due to insufficient cooling. On small areas, the hot nozzle stays on top of the part, so it can not cool and not solidify. So the nozzle is sort of "wading through hot mud", instead of printing on top of a solid area. Printing a dummy tower next to it, helps, but does not eliminate the problem. For overhangs, I found that printing in thicker layers makes them curl up less. Here too: it reduces the effect, but does not eliminate it. On overhangs, the freshly applied material is hanging partly in the air, and it has no or very little suppor
  5. If too moist, under a microscope you can see bubbles in the extruded plastic, due to water forming into steam (=gas), and during printing the plastic is solidifying before the water-vapour had time to condense and being absorbed by the plastic again. So, if the prints have a foamy effect, you could expect too much water-absorption in the filament. If you wouldn't have a microscope, sometimes a smartphone camera with close-up lens add-on could be enough for good photos. Or even a simple webcam with close-up lens. This is the quality you can achieve with a simple webcam,
  6. The salt-concentration does not really matter. I just pour some salt in a bottle, and stir it. After wiping, it should just leave a *very thin mist* on the glass. Definitely no thick, crusty layers, that reduces bonding again. Thinner is better. I am not sure why it works, chemically or physically, but for me it works, so... The photo with the gray above is about right (although contrast is enhanced in Photoshop, in reality it looks less), but in the photo with the red print, there is too much salt. But before applying the salt water, make sure the glass is clean: clean
  7. I use my "salt method" for PLA: wipe the glass with a tissue moistened with salt water, immediately prior to printing. This should leave a thin, almost invisible mist of salt on the glass. For PLA this greatly increases bonding while the bed is hot (compared to printing on bare glass), but there is no bonding at all when cold, so the prints come off by themself. I don't need to take the glass out of the printer anymore. Just re-wipe for the next print, and go. For PET, it slightly reduces bonding, so the glass does not chip. I haven't tried tough PLA yet. Fo
  8. There do exist several clamps and guiding systems to prevent that. Some are mounted on the printers, some on the spoolholders, and some slide on the edges of the spools. Long ago I made a slider for my colorFabb spools, after I also had this problem. In fact, I had two problems: originally, some filaments were wound way too stiff on the spool, so it required way too much force to unwind it, it acted like a strong spring resisting unwinding. I had to manually unwind and straighten some filament first. But then it tended to fall off the spool sideways. This slider only worked on spoo
  9. As long as you don't have dedicated doors and covers, you could start with a simple sheet of plastic as front door: for example the sheets used to protect A4-documents. I was wondering: how comes you have such cold temperatures in *summer*, and then even in Africa? But then I realised your summers and winters are the inverse of ours. :-)
  10. I my (different) Cura-version this worked. Maybe try a couple of different pictures, to find out whether it is a Cura-issue, settings-issue, or a defect in the file?
  11. Yes, I do fully understand the concerns about waste; I am pro recycling too. But the recycling process itself should not cost more energy and resources, and produce more waste, than making new things. Otherwise it would be a lose-lose situation: you would get inferior products at a higher environmental cost. A 100% recycled cardboard item had to be made fresh in one of the cycles before, before it can be recycled. That first-make is what costs lots of trees. Further, both fresh and recycled cardboard and paper consume huge amounts of energy and fresh water: the paper/cardboard has
  12. In the beginning I used the glue stick (without wiping it afterwards, I didn't know that trick back then). But this gave an ugly bottom layer indeed, and non-optimal bonding. I also tried printing on bare glass without any glue: in dry weather this would work reasonably, but in wet weather it would lift off and cause defects like yours. Also, greasy glass would cause this effect. Cleaning with soap and window-cleaner can also produce this, since soap reduces bonding: you can't glue anything to soap. So, now I thoroughly degrease the glass first, and then wash it with pure luke-warm
  13. Yes indeed, I have a lab, and a professional fume extraction cabinet for chemical and biochemical fumes. So I use it in this cabinet. In addition I use extra safety glasses (swimwear style googles that fully cover the eyes). And I don't touch the liquid, I use brushes or dipping instead, and chemically resistant gloves when there is risk of touching. However, I do think you can use it at home, but outdoors only, upwards of the wind, with good safety glasses of course, and gloves. No spectators, unless well educated on the subject and well protected. Definitely no babies, no toddler
  14. If this is on the bottom of the print (=touching the glass), or a very thin print of only 1 or 2 layers, I would suspect grease or oil on the glass, so it does not stick and lifts off. But if this is on the top of a thicker print (hard to see on photo), it is something else: maybe too little infill, or a too thin top surface? For this sort of things, you could best watch closely while printing: often you can see what is happening, and why. For example, if there would be oil on the glass, you can see how the filament does not stick in certain areas and is dragged around. Or you can
  15. I do understand what you mean, but I don't know if there is a setting for that. What could also help is making the walls and top shell thicker. But if you are going to cast concrete anyway, what about using the model as a base for making a mould, and cast the whole model in concrete? So you have a fully concrete model without plastic? In a CAD-editor, subtract the model from a block, so you have the inverse hollow shape of the model. Cut that block into two parts (or more if required), so the cast can be released from it later on. Add alignment features so both halves s
  16. If you have this only with a 0.25mm nozzle, but not with a 0.4mm nozzle, maybe you are printing too hot for it, and the heat still creeps up into the filament due to not enough filament flow? Or the filament begins to decompose? If you do a cold pull (atomic pull), the tip should look like the orange one at the very bottom here (minus the color-change, this was when changing colors, to clean the nozzle). If it looks like the white one, with a thick ring or blob where the teflon meets the metal part of the nozzle, then the teflon is definitely worn-out. Also, it could be
  17. Plastic folders crumbling apart after sitting in the daylight for a couple of years. And this was even behind sun-shielding green glass, which should catch most of the UV-light. These folders are usually made of PE or PP, but I have seen similar problems with other plastics. Last month I had a dustbin falling apart. A couple of years ago I have seen this in "weatherproof" garden chairs... That is why I would not trust plastics too much for load-bearing outdoor use, unless they are specifically tested and approved for it. 3D-printing materials are relatively new, and we
  18. A 0.20mm line as designed in CAD might vary between 0.19mm and 0.21mm after exporting to STL, because the STL-file consists of straight line-segments, instead of smooth curves. The 0.19mm areas are likely to cause problems. Idem for lines of 0.40mm in CAD, for printing on a 0.40mm nozzle. I prefer to optimise the design in CAD, rather than rely on doing tricks in the slicer. So I design the lines a bit thicker in CAD: usually 0.5mm for my 0.4mm nozzles: this prints well, and aligns well on a 0.5mm grid while drawing. Maybe try 0.25mm lines for your 0.20mm nozzle? But I
  19. If you have a single-nozzle printer, and you can do CAD, then consider designing your own supports in CAD. Test various concepts and dimensions on a small testmodel, before doing large models. Standard supports are good for standard situations. But special cases might be better off with custom designs. A few examples: Pink and orange supports with custom brim to prevent them from getting knocked over. These are stable and solid supports, so I can grab them with a plier and wiggle them out. This model is way too small to get in there with a knife.
  20. In my experience the "insect antennas" are caused by the nozzle leaking while traveling through air. Upon reaching the next wall, that drop is deposited on the side of the wall. The next layer, the drop is deposited on the already existing drop, and so on, creating the "insect antenna" effect. Watch closely, then you see it happening. In PLA this is rare, but in more rubbery materials when molten, like PET, it is common. You can easily worsen the effect by switching off retraction, or by printing faster (=more pressure in the nozzle, thus more leaking). Reducing it can be done by p
  21. This looks like a bit underextrusion. There is a video on this forum about possible causes and solutions for underextrusion, I think from user gr5. See if you can find that (I don't know its exact name, nor link to it). Further, if you could post more details such as material and settings, and a project-file of your settings, some people on this forum might be able to analyse it and give more advise.
  22. I have been printing with older spools of PLA without problems. But I do store them in a sealed box with dessiccant. It is true that old PLA gets harder, stiffer and more brittle, so it may be more difficult to find and to unwind from the spool. But don't throw the old spools away yet: first try drying them in an oven at 45°C for several hours, but well below its glass transition temp where it gets soft. Store in sealed boxes with dessicant. And use a bonding method for improved sticking to the glass: I use my "salt method": wiping the bed with a tissue moistened with s
  23. Printing slow, in thin layers, and with all speeds the same (=outer & inner wall, infill), also helps. But it does not eliminate the effect, it just might get it into an acceptable range.
  24. I just took a look at the portable ladder in my lab: it is both riveted and welded. This makes it feel rock solid. If only riveted, each connection could still pivot a bit, causing a wobbly feeling. If only welded, the welds could be superficially glued instead of really melted together. I can't weld myself, but I heard from a professional welder that welding aluminum is difficult due to the very high temperatures required to melt the oxide layer. If not high enough, the connection may slightly stick, but is not welded and will separate under load. If yours will be mounted to a wal
  25. Technically, it will probably work well if you design the parts thick and massive enough, if load is distributed well (=no stress points, correct orientation of layers), and if you print them correctly (temp, fill, flow), and regularly test for degradation and replace them. But personally, I would not really trust it. I wouldn't trust any plastic parts for such purposes. I have seen too many plastic things crumbling apart or breaking after a couple of years: dustbins, bottles, gardening tools, plastic toys, food boxes, garden tables and chairs, car bumpers, all sorts of composite c
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