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geert_2

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Everything posted by geert_2

  1. Just wondering: while printing, can you see it stuttering? Or if you put your finger on the head, can you feel more vibrations in the head than in the other printer? And if you put your finger on the feeder, or the filament just before the feeder: do you feel (more) stuttering? This might give a clue whether it is mechanical in the head drive train, in the feeder traject, or electrical due to temperature changes, or power supply changes, or interference or something?
  2. My experience is similar: print as slow and as cool as you can, and in thin layers. Also try the opposite, print fast, hot, and in thick layers, and see how that works. By exagerrating (here in the wrong direction) you get a better understanding of the effects of these settings. Stay with the printer and watch what happens. You can also adjust settings (speed, temp, flow rate,...) on the fly up and down, to see how they affect the print. Keep watching it: this gives a lot of understanding. Obviously do this on small test pieces that don't take too much time and material
  3. There is a post of me with more tips for single nozzle - single material supports, but I can't immediately find it. Anyway, here a few of my standard pics with tips: Tiny custom support of 10mm wide (dark blue) for the overhang. Ribs on top (0.5mm) allow tighter gaps, but still prevent the support from sticking too hard. Supports as thin layers, not connected. When printing they will sag a bit, but can be peeled off one by one. Usefullness depends on the model. Free hanging support concept for overhangs. The inverted staircase reduces
  4. So you mean that you get underextrusion on long lines of infill, and overextrusion on very short ones? I believe the overextrusion is caused by the nozzle having to slow down in order to take the 180° corner at each end of a line. But the extrusion rate keeps going, because pressure in the nozzle does not immediately drop to zero, so it momentarily overextrudes at corners. Those very short lines consist of nothing but corners. Printing a lot slower, and a bit cooler, should improve this but won't eliminate it. There may be other settings you could adjust, but I don't know them.
  5. Usually nylon, polyethylene, and polypropylene are very hard to glue. Also PET can be somewhat hard to glue. Maybe you have a chance with these? But I haven't printed with the first three, only with PLA and PET, so I don't know if and how well they print on an UM2. Before buying filament, maybe you could test what the UV-ink does on cheap parts in these materials? E.g. PE or PP boxes for the fridge, nylon screws, PET bottles,...? On a 3d-printed part it will probably stick a bit more, due to the layer lines that give more grip. Another option could be to spray the PLA w
  6. If it is lost anyway, I would also try to disassemble it, even if only to see how it is made.
  7. I think that "ring" on your last cold pull pic should probably not be there? (See the very left border of the pic.) Long ago I have seen a short video of a coupler that did not fit well, and molten filament came in-between nozzle and coupler, pushing the coupler up like a hydraulic cylinder. I don't remember the cause, but this could happen if there is burned residue sitting between nozzle and coupler, so there is a gap. You might want to check that? But I also think you should double-check if the third fan keeps running well while printing. Worn-out or dirty fans might start well,
  8. To me it looks like you used a bit too much glue stick. Only use a little bit, and then spread and wipe it smooth with a wet tissue. For printing PLA, I do not use any glue at all, nor any blue tape. After thoroughly cleaning the glass, and then cleaning again with warm tap water only (no soap, no detergents), I wipe the glass with a tissue moistened with salt water. I gently keep wiping until it dries in a thin mist of salt stuck to the glass, almost invisible. My "salt method". See here for an old manual: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
  9. Thanks for the good idea. I have one glass upside-down. But this may come in handy one time if another chunk would be torn-out.
  10. So I made a nice pic to illustrate this concept of lubricating the bearings of old fans. This is a 386-computer fan, not an Ultimaker fan, but the concept is the same. I have done several of these in the old days. Feel with your fingernail where the edge of the bearing is. Mark this with a pen if necessary (see red circle here). Then inject a little drop near the top (thus near what would be the top after mounting it again). A little drop, not a whole syringe: you don't want it to spill oil on the glass and destroy bonding. Somewhat thicker bearing oil works best in my experience.
  11. Just out of curiosity: when handling resins, do you do that in daylight, or in a dim-lit room, or an almost dark room? To prevent them from self-curing? How sensitive are these resins, let's say if you leave them out in daylight or in the sun? How much time do you have before they self-cure? I am asking this because I have worked with dental light-cured resin pastes: the white filling materials for teeth. And you should definitely not use them for longer than half a minute in bright light.
  12. My experience: try to avoid self-tapping screws, or thread-tapping, in PLA. Tapping is likely to melt the plastic and destroy the thread, even when tapping/screwing very slowly and carefully. At least in the sizes M3 and M4 that I use most. The heat generated by the friction and deformation from tapping immediately goes above 50°C. Also, PLA is sensitive to creep-deformation under load, so it comes lose soon. It might work with other materials like PET, but I haven't tried that yet. This is much less of a problem with inserted real nuts/inserts. Although I haven't tried it myself y
  13. I have also been wondering about that. I have seen the toy a couple of times, yes. But I think with a bit of searching in a hobby-shop or brico-shop, people should be able to find replacement wheels, like the standard wheels for shopping carts, or chairs,... Anyway, 3D-printing them will be an excellent test of layer-bonding. If kids can't destroy it, then nothing will. :-)
  14. Not an official answer, but based on common sense, I think the problems are not going to be the plastics. Kids wear plastic rings and armbands all the time, and most clothing is from plastic these days. But it will rather be the tiny openings in which bacteria and dirt can get a grip. So you would want to make your prints as smooth as possible, with as little tiny openings and layer lines as possible. PLA is bio-degradable, so theoretically bacteria could eat it. But I have printed PLA sifts for the sink in my laboratory, and after years of use in the wet and dirt, they don't seem
  15. Another thing I forgot: smooth the mould prior to casting the silicone. Every detail will be replicated, so layer lines will be visible in the silicone too. This will make removal of the part from the mould more difficult, and it will make it more difficult to clean. So, sand, polish, chemically smooth ("acetoning"), or paint the mould. This is well spent time.
  16. Yes, if you have the tools, I can imagine that heatsinking-in real knurled inserts is the best. Probably the strongest also, less likely to go rotating. For completeness, if the design allows it, and if forces are low, inserting the nut via side-openings might also be an option. See the pic below. I use this for light clamps. Advantage is that this is very easy.
  17. This is a good This is a good idea, worth remembering. This concept could be usefull for lots of other models too.
  18. One extra note: if you use a thin, slow-curing silicone for casting, be sure that the lower half of the mould is absolutely water-tight. Silicone slowly creeps into the tiniest openings, even only microns wide, and would leak away. With thick, fast curing silicones, this is less of a problem, as they are already cured before they have time to leak away. If there are non-watertight seams, you can close them with plasticine or wax. Another option is to make the whole mould out of plasticine. Be sure to use non-sulphur plasticine, as sulphur inhibits curing of silicone. I
  19. The little rear fan (nozzle-cooling) should always be on when printing (when the nozzle is above 40°C). If not, check if there are no hairs and strings of filament or dust stuck in it. Check the connections and wires. If the bearings would be worn-out, or the wires broken, replace.
  20. If you say the fan is "making noises", it could be: - There are filament hairs and strings stuck into it, hindering the rotation. - Or the fan bearings are worn-out. This was very common on similar CPU-fans in older computers (286-386-etc.). If you don't have a replacement yet, you can extend the life of the fan a little bit by lubricating the bearings: using a needle, cut through the silver label covering the bearing, and then inject a drop of bearing oil into it. This is obviously not a permanent solution, but I did use this quite often on computer fans in the old days,
  21. Good. And yes, this technology will come with its own new learning curve. I also like the fine details. I can imagine that for juwelry or very small railroad models, etc., this is fantastic. In the beginning such resins tended to get brittle after exposure to the sun, because it was UV- or light-cured, and it kept curing further. Also in the beginning, freshly printed parts were subject to creep deformation on heavy loads. You had to let them post-cure first. This was years ago, and I don't know how things evolved since then. But it might be a good idea to test this on a couple of
  22. Have you checked if the nozzle cooling fan is working? If not, this would give this phenomena. On an UM2 this is the little fan behind the nozzles; but I am not sure where it is on an UM3. Occasionally this fan may suck up hairs and strings of filament, and get stuck.
  23. Maybe from another computer you could recover a dedicated graphics card, and put that into your computer? Or use older Cura versions? Depending on what you want to print, on which machine (e.g. on older UM-printers), this might be sufficient?
  24. I have heard that there should be absolutely no broken-off bits and pieces of previous models left in the vat, because that would ruin the next prints. Maybe that is why they empty and clean the vat? And sift the resin? But I have no personal experience, except for seeing it once. And yes, the "mess" and chemicals were some of the main reasons why we chose for FDM back then... But I think you would best search a dedicated resin-printing forum for this, they are going to have way more experience and tips.
  25. Looks good. The "cold" metal suits this model. Instead of plating, have you ever tried automobile "chrome" painting sprays? Not the "metalic" sort with little flakes, but the real "chrome" look spray-cans? The sort that is used on car bumpers, wheels, and decorative chrome stripings? I have seen it on model cars, but I have never used it myself, so I don't know what preparation is required, nor how well it withstands bending, temperature, weather, etc. Migth be worth trying on a scrap piece.
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