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geert_2

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Everything posted by geert_2

  1. Did you print this with an enclosed front? If not, I could imagine that too much cold ambient airflow would cause this? Or maybe too much cooling fan? I have no experience with this material, but generally high-temp materials need an enclosed front and little or no cooling fan for good layer-adhesion. Otherwise the new layer won't melt into the previous layer.
  2. Originally I also used a piece of plain paper, but now I just do it visually: I print a border of 15cm x 15cm, one layer thick, with a skirt of 10 lines, and then adjust on the fly while it is printing this skirt. This works well for my UM2; I don't know if this is recommended for later printers like UM3 or 5.
  3. Yes, that is how I understood it. :-) To be totally sure I just tried it on my old Cura 14.09, and there the function is named "Split object into parts". It works, and you can indeed delete each of the parts separately afterwards. So, you could save the remaining as gcode, and print them one by one in this way. However, it does have side-effects: if there are hollows in an object, like my watermark text, these will also be extracted as separate objects... Lol. Which should have been this:
  4. This is a good idea. Even though I printed so many "dummy cooling towers" next to my models, this has never occured to me. I am going to borrow this idea. :-)
  5. I think in older Cura versions it was possible to "split object in parts" or something similar? This would split a model into all its parts, and these would all be distributed on the build plate separately. Then you could delete the unwanted parts one by one, and only keep the desired ones. You would have to redo this whole sequence of splitting and deleting for every part, so it is a bit cumbersome, but it could be a temporary workaround to get a job done. I don't know if this is still possible in the newest versions of Cura (I haven't tried)?
  6. I guess that your model has not enough cooling. Print this slow, as cool as possible, and print a dummy model next to the real model. Try a dummy cube, or an inverse of the model. So that the hot nozzle has to spend some time away from the real model, and the real model gets time to cool. But as said, it is a guess. See this conceptual example: Edit: it looks like this effect with and without dummy cooling tower:
  7. I didn't know I had a photo of the above effect: expansion of the molten filament after exiting the nozzle. But I just stumbled upon it again, so here it is. You can clearly see how the sausage expands immediately after exiting the nozzle, during the first mm. In the zoomed-out image the sideways expansion is from ca. 46 pixels to ca. 51 pixels, thus about 10%, very rough estimation. Nozzle opening is 0.40mm, so that would be from 0.40mm to ca. 0.44mm.
  8. That vertical banding is the "ringing" gr5 referred to: the mechanical oscillations of the print head after taking a sharp corner at high speed, due to its weight, play in the bearings, and the rubber drive belts. So, printing slower reduces this effect. You could also try the opposite: printed a lot faster, and see how the effect changes. For the best settings, you need to ask gr5, as I never experimented with these settings. You can also see the effect in the red print below, due to the light-reflections which exagerrate it. For size-reference: the nylon screw is an M
  9. No, it's based on my experience with my own printers. The teflon couplers tended to wear out quite fast if the printer was running on higher temperatures (above 220...230°C). And that resulted in irregular prints and underextrusion. From the outside it can be difficult to see if the coupler is worn out, because that is only at the inside. But there can be other causes of irregularities: irregular friction in the feeding traject also has a lot of influence on these printers. For example, an irregularly wound spool, kinks in the filament, or a spool nearly empty (=bending radius too
  10. There is a way to mimick this effect, but it requires changing the CAD model. On top of your model, create these hexagons, and leave a very tiny gap in-between them, for example 0.001mm. This gap will fuse while printed, but the slicer will see it as separate polygons, and slice them accordingly. So it will outline each hexagon separately. Then use multiple outlines for wall thickness. But the problem is that the nozzle has to go from the center to the edge after completing each hexagon, and this may create ugly lines or defects.
  11. Quite some time ago this has been discussed on this forum, with lots of photos. But I don't know the topic name. Maybe you can find it back? They did this by first printing one layer ("the symbol"), in a thin layer height (e.g. 0.1mm). And then, using a thicker layer height (e.g. 0.3mm), they printed the next part over the first, without removing that model from the build plate. But I don't remember the details. Some people got really nice results.
  12. If it is an old standard UM2, chances are that the white teflon coupler on the nozzle is also worn out. If you do a cold pull ("atomic pull"), and it has a huge blob at the seam between nozzle and teflon coupler, it is worn out and needs replacement. See the blob in the white cone below, which shouldn't be there at all. It should look straight like the orange cone at the bottom. Obviously, I did these atomic pulls while changing filament color, so they have both orange and white. Yours should have only one color, and no black dirt. If it has black dirt, do
  13. For keeping filament dry, I use these bags with desiccant (left=package, right=actual bag), and keep all in a big sealed food box. The blue dot turns pink when moist. These bags can be dried in a microwave, or conventional oven at low temp. They can be found in car-accessory shops as they are used for drying car interiors. For reference: the ruler is in cm. This is good to keep filament dry. But to actually dry already wet filament, it may not be enough: you may need elevated temperatures to first "shake the watermolecules loose" from the plastic, before this bag can absorb them.
  14. Make a small and simple test piece and try to print that with default values: 40...50mm/s, 200...210°C, 0.1...0.2mm layers. Anyway, 240°C is way too hot for PLA: this could easily make the PLA decompose and block the nozzle. So you would first need to check that the nozzle is clean. Then also check if the teflon coupler is not worn-out, if the little fan at the back of the nozzle is working well, if there are no kinks in the filament, if the spool can unwind freely, etc. But definitely start by cleaning the nozzle until you can easily push filament through manually. Sea
  15. The little "insect antennas" are when the nozzle leaks a little bit while traveling through the air. Upon arriving at the next wall, that droplet is deposited on the side of the wall. On the next layer, the drop is deposited on the previous drop, since that is now what the nozzle encounters first after flying through the air. And so on..., causing upwards tilted "insect antennas". I haven't printed with nylon yet, so I can't give any recommendations. For PLA, usually printing slow and cool helps, but I don't know how that would work for nylon: it might negatively affect layer-bondi
  16. The "0.1mm" should be "1.0mm", to bridge the gap of 1mm between walls and support. Also see the STL-file above, and the picture, where most other major dimensions are 1.0mm also (the width of all plates, and the stair-cases). This is what works for me, but of course, you may want to adapt it to your situation. Different materials, models, and printing circumstances may require different parameters. Before printing big models, I would recommend you design a few small test models with lots of variations, and print these with your typical setup, so you can see what works best for you.
  17. Wasn't that print head the same as the UM2 (non-plus!)? Or have there been different UM2Go versions? In the first case (=like UM2 non-plus), I think you don't need any spacers, because this was with a spring instead of fixed-length metal piece.
  18. It could also be that the little fan on the back of the nozzle is not working. This would cause the filament to heat up too much, and soften before the nozzle, so it gets too thick and gets stuck. Or that there is a kink in the filament, so it can not unwind from the spool, or not pass through the feeder. Or a totally worn-out white teflon coupler (especially on UM2 non-plus). Or any other obstruction along the whole traject. PS: normally you can just drag and drop photos into your post while writing. It should work, I do this all the time.
  19. I have this phenomenon very occasionally in one of my two UM2s, not in the other. There is no clear indication why, although it is most often when playing around with the control-knob a lot. If I don't touch the knob, it doesn't happen. And it gets worse in very dry weather. So I don't know if this is a firmware-bug, electromagnetic spike issue (heater or steppers switching on or off, causing spikes), electrostatic discharge issue (like sparks in freezing weather), communication-issue between knob/display/mainboard, mainboard hardware, or a combination... The randomity makes me think it might
  20. Enable the standard supports as Smithy says, or design your own custom supports into the model. Sometimes custom supports may be desirable in special circumstances: for example to make the support stiffer so you can more easily grab and pull it out with pliers, or to make it extend so you can grab it, or to make special holes in it to insert hooks. Usually I prefer to design custom supports into my models, so I have full control. Except for large and easy to reach areas, where the standard supports do a very good job. For example, the red and orange blocks below here ar
  21. Are these diverters also printed in nylon? Or in another material (they don't look like nylon on the photo)? Could you keep us updated on how well they survive outdoors, and if there is any UV-degradation over time? We haven't seen very much outdoor applications on this forum.
  22. This option exists in older Cura-versions, with the "minimum layer time" and "cool head lift" options. I don't know if it still exists in new versions? I tried this, but it did not work very well for me. The problem is that if the nozzle is simply moved away while waiting, the filament gets hotter and more liquid in the nozzle. So it starts leaking more, and the more liquid plastic flows differently upon starting the next layer. Further, the added heat during this waiting period, also has to be removed in the cooling cycle, so it does not really help very much. Any differences in l
  23. Originally, I also thought so. But I got inconsistent results when measuring these extruded strands: they could be anywhere between 0.40 and 0.60mm. So, something was off, but I didn't know what. Later I saw a Youtube-video of "nozzle-developers" (I don't remember from which company), and they said this very common assumption was not true. When the plastic comes out of the nozzle, it is still molten. Molten strands of plastic usually have a strong tendency to contract. This is because during extrusion their very long molecule chains are stretched. These chains are then under a very
  24. You could do this kind of tests on small test pieces, of only a few mm high. In these tests, provide as much different features as realistic for your typical models: different line-widths, different holes, different extensions (poles), overhangs, curves and roundings, bridges,... If you use bolts and nuts, also model the required hex-recessions into these tests. Idem for dovetail- or snap-fit mechanisms, etc...
  25. In my experience: - If bed temp is too low: the model is very stiff, and the model-edges generally do not lift much, but the whole model may suddenly pop-off the glass, due to insufficient bonding. - If bed temp is too high: the bottom of the model stays too soft, so the edges may lift due to shrinkage forces acting upon the higher layers, and the whole model may gradually peel off the glass. - Walls too thin: walls are pulled inwards (similar to the effect you see), and the models tends to lift at the edges and gradually come off the glass. It is like a cardboard box tha
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