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geert_2

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Everything posted by geert_2

  1. Thanks for the photos. It might be fillers in the black that decompose due to the acetone? Or due to UV-light, or age, moisture, or whatever else? Or the fillers that reduce layer bonding, and thus make it more prone to splitting? Also, I think manufacturer should mention in their specs for each filament: "Can be acetone-smoothed" or "Can be whatever-smoothed", and then the recommended product, time, method (brushing, wiping, dipping, vapour, whatever), and amount (thin, thick). I have just smoothed a handle (using your brush-on method), yellow PLA, and now
  2. I have colorFabb glowfill, and indeed, it does not glow for very long. It is very bright for a *very short* time, and then quickly fades. Usefull brightness as a sign is a few minutes, maybe 5 at best. And then it is still barely visible, but unreadable, in pitch black darkness for indeed maybe 20 min. Just a blurred pale green shade. Useless as emergency exit sign, or as night-light in a room. In the old days they had radio-active glow-in-the-dark paints, used on clocks. These did glow *very* bright all night, for +10 years. This was really fascinating, and very usefull. But these
  3. I believe the effect you see is overextrusion, due to the printer slowing down at the corners or ends, but the nozzle pressure is still up and takes some time to dissipate by leaking away. This gets more visible when printing lots of small segments. Printing slower and cooler helps, but does not eliminate the effect. But for me it is no problem. I haven't tried features like "coasting" (if I remember the name correctly, stopping to extrude just before a corner, so that pressure has time to drop). Maybe this might help? But if you overdo it, it might cause gaps at the st
  4. I have tried it this way: - cut off both filament ends at 90°, - heat a knife in a flame, - align both filament ends in a holder (see pic), and push them down with your fingers, - insert the hot knife in-between both ends, and push both ends onto the hot knife (don't push your fingers onto the hot knife), - let these ends melt a little bit, - remove knife, and push both ends together, so they melt into each other, - keep pushing them down, and let them cool and solidify, - using a Dremel tool or similar, cut off the flanges, otherwise it won't go through
  5. Hoi cloakfiend, Have you ever tried *post-curing* an acetoned model? Thus: print, sand, acetone, wipe, dry, as usual, but then let it sit at an elevated temperature for maybe a day, or two days? The temp has to be above glass-transition temp, maybe 60-70°C, but below melting the model of course (may depend on the model what it can withstand). This could reduce residual stresses, so it might be less likely to split later on. And then primer, paint or plate as usual. If it is going to split anyway, it might already split during this process. I am not sure it is going to w
  6. Another factor is cooling: in small models it doesn't get enough cooling time. So the whole thing stays soft and sags. On sharp corners, the strand is pulled inwards like a rubber band. See the tests I did a few months ago. This is PET. Nozzle = 0.4mm. Layer-thickness from left to right (mm): 0.4, 0.3, 0.2, 0.1, 0.06. Top row: 50mm/s, bottom row: 10mm/s. You see the same rounding and not-enough-cooling effects in the thickest layers (left), although less than in your tests.
  7. The screendumps below show why you should not use SketchUp. The vectors do not match up, they do not connect. So you do not get watertight solid models. SketchUp models are a mix of separate surfaces and half-solid parts. Especially if you then do boolean operations on these, it becomes a mess. Below this effect is shown in simple text, before it is extruded into 3D, but the same also happens in other SketchUp models. SketchUp was designed for visual representations only: of buildings, like in games, or for Google's original Earth and Maps views. Not for 3D-printing.
  8. Also try using mechanically interlocking features. Since this is highly recommended for injection moulding in overmoulding, according to the manuals, I think it also applies for 3D-printing. At least, it shouldn't hurt. Think of a dovetail system, or hooks, or chains that interlock. Think of these concepts, but then all melted and squeezed into one solid block. Have a look at how it is done in tooth brushes: most of them also have overmoulding with interlocking features.
  9. If you are courageous and have some electronics knowledge, and you want to rule-out the bed-heater influence, you could try to fix a LED-lamp onto the heating-connector. And then babysit the printer to see if the bed-heating LED and print-lines occur at the same moment? (Use a diode + LED + suitable current-limiting resistor, all insulated, not a bare LED alone). But here you risk making short circuits and burning out electronics, so you must know what you are doing. While babysitting a print, also watch if there are any feeding issues: bends in the filament cause increased resista
  10. If it is at *random* heights, or at a fixed height not related to model-features, I would think of a Z-axis issue, such as dirt (thoroughly clean the screw), or play in the nut or driver. But I am not familiar with diagnosing and solving that. If it is always at the exact same height as big changes in print-area, or changes in infill, or changes in wall-thickness, then I would think that there is still something there to improve (thicker walls?), even on bigger models. I have seen models where the infill-pattern shined through the walls, causing indents. A bit similar to the struct
  11. Do you mean that the 8mm rod on which the pulley is mounted, could be shifting (or be shifted) axially, due to too much axial play, or an incorrect plastic spacer? Or one of the pulleys being mounted a bit too far away from the printer-housing? That could also explain the phenomena.
  12. For PET, I get good layer adhesion by printing much slower and cooler, and *without fan*. But then the bridging and overhangs suffer (but most of my models need no bridging and no overhangs). The "printing cooler" is to prevent the filament from burning and decomposing in the nozzle, due to the much longer transit times. I don't know if this would also work for PVC? Anyway, watch out for chlorine gasses, if it would decompose. Should be easy to smell, like in a swimming pool where they overdid it.
  13. I don't have these printers, but on my older UM2, changes in print-area per layer can result in horizontal lines. Especially on smaller models. I think this is due to differences in cooling time per layer, but I am not sure. In your models, are the lines where the solid top and bottom layers begin or end, or where there are big changes in surface area to print? If so, printing with thicker walls, or 100% infill for small models, could help. Also: placing a dummy block next to the real model can help, especially if it is less or more in the inverse shape, or inverse print-area per l
  14. I also had this on one belt on one of my UM2: a squeeking sound which turned out to be caused by the belt rubbing against a flange of a pulley. I gently lubricated the edge of that belt with a little bit of silicone grease. But only the edge, and only a *tiny little bit*. Not on the teeth, otherwise it might skip teeth. And I used *silicone* grease: the thick white sort that is also used for microscopes and binoculars. This does not leak away and does not dry out. Don't use petrochemical oils or greases on rubber: this may damage it. This is not an official
  15. Gradual differences: 1) Maybe a different airflow, different air-temperature, different bed-temperature from left to right? If you would have an IR-thermometer gun available, try measuring the bed temp at several spots. I found that in my old UM2, at 100% fan speed, the bed-temp could drop by 10-15°C locally, when printing small objects in PET, so the fans were always blowing hard on a small area. To compensate for this, I did increase bed temp by 10°C for PET. 2) Differences in cleanness? 3) Differences in bonding layer thickness, or method of applying?
  16. Have you tried measuring if the X- and Y-axis of the printer are perfectly perpendicular? Maybe they are around 89° or 91°, instead of 90.0°?
  17. In the very beginning, on one of my UM2 printers, I had the Z-axis moving down a couple of times during long prints, due to overheating and temporarilty shutting down of the drivers. In mid-print it would fall down 5mm, and then continue printing as if nothing had happened. This was only on long prints, or very intensive use all day. I never had it on the X- or Y-axis, but I can imagine that it is possible too. In my case the solution was to reduce current through the stepper motors. Since then, it never happened again in all those years. If I remember well this was done on the pri
  18. Yes, I can see your viewpoint now. To be honest, I hadn't even thought about existing models from others, it simply didn't cross my mind. 🙂 I design mostly for internal laboratory or hospital use, and 95% of the models don't need supports anyway. So I can design towards easy printability, and I wrote the above from that perspective. Also, I am not using the latest Cura version: for my older UM2 machines, the older versions still work fine, so I can't say much about the latest settings.
  19. In short: - a "CAD-program" is for designing *new* 3D-models, or for modifying existing models. Most CAD-programs create vector drawings, sort of, but then in 3D with solid models. CAD-programs are only for modeling, not for printing. - a "slicer" is for cutting an existing model into thin layers and for generating traveling-paths ("toolpaths") for the nozzle, so that this existing model can be printed layer by layer by the printer nozzle. Slicers are *not* for modeling, only for printing. Cura is a slicer, not a CAD-program. - a slicer may allow you to resc
  20. I think you would best use the "shelling" commands in a CAD program. Or delete the top- or bottom surface in CAD, so you end up with a non-solid surface-only model, which has zero wall-thickness and is unprintable at that moment. And then thicken that surface *outwards* until it is 2x nozzle width, so it becomes a printable solid again. And then design some supports, so that the print can stand upwards or upside down, whatever is required for casting, without toppling over. And if required: add pouring canals, venting canals, cut the mould in two halves, make flanges at the seams,
  21. As I just said in another post. I don't have dual nozzle machines, but due to the lots of reports about PVA-problems, if I had dual nozzles, I would custom design and print most of the support in PLA. And only do a small interface in PVA in-between. And I would use a dovetail to let the PVA grip well into the PLA-support. Like this concept. Then you can design the PLA support structure economically but still very stable. Test this concept on a small test piece first, before doing a large model. And stay with the printer to see what happens during the first attempts.
  22. Yes, that could work. But it could also fuse the support into the model, making it very hard to remove the support without extensive cutting and damaging the model. You have to test this first on a small test-model with variations. If I would have dual nozzle machines, I would use PVA-support in this case. However, to minimise PVA consumption and to maximise stability, I might custom design most of the supports to be printed in PLA, and only do a small PVA interface in-between. And I would use a sort of dovetail to make the PVA- and PLA-supports grip well onto each other. I can't t
  23. As gr5 already mentioned: don't use ordinary PLA: it may work a couple of times, but after a while it gets harder and tends to break. Even when printed in the "right direction". And it has too much permanent creep-deformation under continuous load. I use PET now for snap-fit lockings and keychains. It has enough flexibility to survive, and is still easy enough to print. Haven't tried tough-PLA yet, it's on my to-do list. And indeed, do small test pieces first, until you get them right. I would also recommend that you make keychains, carabiner hooks, cloth hangers, and s
  24. Most consumer electronic components are designed for a long-term maximum operating temperature that you can still touch, although barely, about 60°C. This is heat due to power dissipation in an environment of 25°C. Especially electrolytic capacitors, diodes, small transistors, chips, LEDs,... are sensitive. Power transistors and -amplifiers, and resistors, can usually withstand a lot more. Above that temperature the components usually don't die immediately, but their life shortens a lot. And power drivers need to be able to release their heat. I don't know about Ultimaker electronics, but I do
  25. Glad you found a solution. I like the idea of printing topographical maps. Where did you find good quality images? Another question: do I understand it correctly that the main purpose of this procedure is to round the 4 corners of the image (but not the mountains themself)? Like a plastic bank card? And to "drill" a hole in it? If so, couldn't the same be achieved in Photoshop by changing the black and white levels of the image, and adding a black or white border around it? (Depending on whether black or white is zero height?) And then import it in Cura and
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