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geert_2

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Everything posted by geert_2

  1. I *do* think it is infill shining through, because the infill pattern in the first pic (of Cura) exactly matches the lines in the second pic (the photo). Maybe too much overlap between infill and walls? Or indeed overextrusion like yellowshark suggests: if the infill overextrudes upon slowing down at the end, causing a sort of blob, then I can imagine that this shows through, since the edge has nowhere to go but outwards. This effect would get worse at higher speeds, since the pressure in the nozzle can not immediately go down to zero when the printer slows down. Printing hotter could also inc
  2. I do not have an answer to your question, but there might be other issues with your approach: - Overhanging edges tend to curl up, which causes the nozzle to bang into these curls, and which might knock the model off the glass. - The support material might not stick very well to the steep slopes of the arches. I think it might be worth trying vertical support columns and then a horizontal dummy bridge. Then you only need support material on top of that bridge, so it would consume even less support material. The bottom of that dummy bridge will of course sag, but th
  3. I don't know the UMO, but on an UM2 there is a little fan at the back of the nozzle, cooling the seam between nozzle, teflon coupler and bowden tube. Probably there is one on the UMO too? Did you check if this little fan is running at full speed? If not running at all, or if too slow, heat would indeed creep up into the filament, melt it above the nozzle, and make feeding and printing impossible. The fan could be worn-out, or it could have sucked-up strings or hairs from prints and gotten stuck, or a cable came off?
  4. Nice. And what method did you use for bonding to the glass?
  5. My models are full of small circles and tiny features, and they print fine, both in PLA and PET. This is a keychain-miniature of dental models used in the hospital. I tend to print these things rather slow (25...30mm/s) and cool (195...200°C for PLA; 210...220°C for PET), bed temp 60°C for PLA, and 80...90°C for PET. Bed is leveled rather close so the first layer is squeezed well (manual leveling on old UM2 printers). Everything else is pretty much default (I am using an older version of Cura). For reference: text caps height = 3.5mm; character legs are 0.5mm wide.
  6. Although this is not an answer to your question, it might also improve the situation: the cause of warping might also be because of the way you clean your glass plate, the bonding method you use (or lack of), the distance between nozzle and bed, and the environmental situation (air moisture, temp). Since I started using the "salt method" for bonding, I don't have Ultimaker PLA warping anymore. I use their nice "Pearl" color; I don't know about other colors. The "salt method" = first clean the glass with whatever means you want, e.g. isopropyl alcohol, acetone,... (but n
  7. Yes, I do fully understand that concern. I am feeling the same about post-processing work; I don't like it. :-) But printing vertically with lots of retractions, and the nozzle moving through the air a lot, also takes time, in addition to creating the imperfections you have seen. Depending on your designs and your printer, there might come a point where printing flat goes faster, and requires less post-processing than smoothing out these imperfections. So you could get more done with less effort. Maybe... If you plan on doing lots of prints, I think it might be a good
  8. This looks like a fun project for kids. Did you print each cutter-blade assembly in one piece, or print each blade separately and then mount them on a rod?
  9. Maybe printing the walls flat on their back, and then glueing the pieces together, might give better results? Similar to the HO-model railroad houses we had as kids from Faller, Vollmer, Kibri, etc... Then the material flow is more constant and the print head does not need to travel through air as much. Or maybe you could print the main wall vertically, just like you did now, but print only the windows flat on their back, and then assemble? That might give a better layer line pattern? Also, using sand- and stone-colors (beige, warm grey, light grey, cream) could also he
  10. I hope you speak a bit of English. As far as I know, almost all magnets lose their magnetic characteristics at elevated temperatures, because the iron (or other) magnetic particles become looser and their alignment changes into random. For neodymium this is around 80...90°C if I remember well (but verify it, as I could be wrong). 3D-printing is done above 200°C... So, I think you would need to print a magnetisable material, and then later turn that into a permanent magnet by exposing it to a very strong magnetic field. I don't know how that is done exactly,
  11. To me this seems reasonably okay, it looks like what you could expect at 0.3mm layer height. Although there seems to be a bit of "elephant feet" at the first layers (=thick bottom). There may be other reasons, but often this is caused by a bed temperature that is a little bit too high for the material, so the first layers sag a bit. Maybe you could try to lower your bed temperature by 5°C and test if the model still sticks well? Stay with the print, in case the model would come off, so you can abort. When printing on a glass bed (I don't know what bed your printer has), we often ha
  12. I usually print my medical models with 100% infill, which by nature very much reduces the possibilities of holes and leaks, althoug of course there are always thin "canals" of entrapped air in-between the extruded sausages, that are not filled. You can not avoid this. Printing slow also helps, and with enough extrusion: better a little bit over- than underextrusion. Also, user cloakfiend's acetone smoothing works very well: this tends to fill tiny gaps. Search for acetone smoothing on this forum. Further options: spraying a thick varnisch? Or dipping the mod
  13. No shame on you. We do not always have the time to fully explain things. Further, I am working in an educational institution (university), where we are by law required to: "provide education, research and service to the community". Often I also have to provide explanations and guidance to collegues and PhD students about computers, software, and laboratory equipment. So I am used to it, and it fits within my job. Also, I enjoy sharing knowledge, so I don't mind doing this at all. :-)
  14. If you use a 9V battery, and you put the LEDs in series, it will work with the same resistor value, but just give a bit less light. But usually I would prefer to recalculate the resistor: voltage over resistor = battery voltage minus first LED voltage minus second LED voltage. Vr = Vs - Vled1 - Vled2 For an educated guess, that would be: 9V - 2V - 2V = 5V over the resistor (as a crude order of magnitude). Use two identical LEDs. And then calculate the resistor, based on the recommended current through the LED. If it is a high-efficiency
  15. Now that you say this, I remember: in the beginning I used to wipe the nozzle with a tissue wetted with silicon oil, and PTFE-oil: sometimes the first, sometimes the second. These sprays can be found in car shops. This also reduced accumulation. It seems that after some time the nozzle gets a coating of PTFE and/or silicone, and it gets less sticky. There is still some build-up of goo, but less. So, now I don't need to wipe them with oil anymore; I just clean them immediately after each print.
  16. Google for "simple led circuits" and then select "images". This shows the setup. Always keep in mind: LEDs do need a resistor to limit current, otherwise they burn out! Usually the voltage over a LED is between 1.6V (old red LED) and 2.5...3V (blue and white LEDs). The recommended current for a nice illumination can go from 1mA to 10mA usually, depending on the LED. Don't come near the maximum current through the LED, always stay well below 50% of the maximum. So you need to look up the specs of your LED, or measure them: - normal voltage over the LED= Vled = ?
  17. The PET I used (which I think is a sort of polyester, just like CPE?) has a tendency to accumulate on the nozzle while printing, and then this accumulation discolors into a thick light brown goo, which eventually sags and gets deposited on the print as big brown blobs. Also, while traveling through space, the nozzle has a tendency to leak, and then upon arriving on the next wall, a blob is deposited on the side. Especially when printing fast, due to the nozzle-pressure not reducing immediately. In my UM2, printing slow reduces the effect, but does not eliminate it.
  18. I don't know about the UMO, but on the UM2 the bushings definitely need oil. Oil does not only reduce friction, thus it prevents metal on metal wear, but it also allows trapped dust to be removed, thereby again reducing wear. Officially the UM2 rods need thin sewing machine oil. But I found that this dries too quickly (may depend on oil brand and composition), so now I use a high grade hydraulic oil, also used in industrial applications like hydraulic test benches, tractors, bulldozers,... This oil does not dry out at all, it lubricates well, and it contains anti-corrosion and anti
  19. Can't you tighten the clips carefully with a plier? But I agree, a sort of quick lock mechanism like in camera-equipment would be good, similar to this (the one on top). Although I don't know how well this holds under repeated vibrations for days, which we have in 3D-printing. At least, it would require a strong spring, not just mechanical friction, to hold the lock.
  20. I print most models in PLA (95%), and they are functional: good enough for use in the hospital, and good enough for mould making. But they can't stand the heat of a car interior, even not in mild spring or autumn weather: then they will deform. And of course desinfection has to be done chemically, not by autoclave. Also, PLA is very hard to drill into, or tap threads into, because it melts. Functional items that need flexing, like carabiners or snap-fit locks, will break over time: PLA is not flexible enough, and it hardens over time. Creep is also a factor in PLA: if t
  21. Yes, then he would better concentrate on studying the methods to grow his plants well, how to prune (trim) the leaves and bunches of grapes, how to making the grapes taste well, make the wine taste well, and make it conserve well without turning into vinegar. This is not simple and there is a lot of knowledge involved: grapes need special soil, climate, and treatment. The wine-production itself requires even more knowledge, to prevent it from rotting. Making vinegar or rotten fruit juice is easy, making good wine is not. :-) We had grapes, although we never made wine. But in our
  22. It does exist: in my old Cura that function is called "Print one at a time" (versus the standard "Print all at once"). I don't know the name in newer Cura-versions. However: this needs more room around the piece, to prevent the print head from crashing into already printed items. And if the models are very small, you will run into cooling problems: the nozzle staying on top of the model at +200°C, radiating heat, prevents the model from solidifying and cooling down. Increasing minimum layer time does not help in this case, since the nozzle just stays on top of the print. Moving it
  23. For PET from the brand ICE, I usually print between 215°C and 225°C, slow at 25...30mm/s, and with a bed temperature of 80...90°C. No fan if the model allows it. If I need to use a fan for overhangs, then a higher nozzle temp works better. If I need a fan, then I need to use glue to prevent warping, otherwise I print on bare glass. Most of the time I use the "salt method" (=wiping the glass with salt water, and let that dry into an almost invisible mist of salt stuck to the glass), which slightly reduces bonding for PET, but it makes it much easier to remove the models afterwards,
  24. Depending on the software you used to design the tubes, "deleting" the hollow insides (thus making them solid) might be as simple as just clicking the inside area once, and then press the delete button. Takes a few seconds per tube. In some programs you might even be able to select "all similar hollows" (or something equivalent) after clicking the first inside, and delete all in one shot. It might be worth looking into that?
  25. Wow, that red one looks really smooth, with absolutely no layer lines visible. Did you sand it prior to acetoning, or was it straigth out of the printer?
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