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Everything posted by geert_2

  1. Great idea. This might become a trendsetter if more people see it. Then we might see vampire masks dripping of blood, terminators, the guy with metal teeth from James Bond films (don't remember his name), and so on. Could get really interesting. :-)
  2. I prefer to print a dummy "cooling-model" next to the real model. The dummy can be empty, except for the top which should have a less or more complementary print-area as your problem-area, so the total print time per layer stays almost equal. So the nozzle is moved away from the real model while printing the dummy, and the model has time to cool down. The advantage of the dummy is that the print speed and material flow stay constant, and thus the temperature and viscosity of the molten plastic. Disadvantage is that is wastes some filament. See the pics below. The first pic shows th
  3. Another reasonably easy method: design a nut, add a cone-shape on top, and a rounding at the bottom for easier inserting of the nut. And then subtract that coned nut from your design. Due to the cone on top of the nut, it prints well without causing overhang-problems. See the pics below. This is a metrinch-style design, which gives a tighter fit. This is an M4-nut, and the distance between the "flats" is the standard 7mm. Nylon M4-nuts can be pushed in with a little bit of force, and don't fall out. Although they can be pulled out by inserting a screw and then pulling. I tried prin
  4. The best practice is always to be very gentle with nozzles. No brute force, to avoid damaging brass nozzles, print head, and rods. Even if a rod is bent only 0.05mm, that is a complete layer-height of 0.1mm upon one rotation. I do very gentle cold pulls ("atomic pulls") very week, or every time I change filament color or type, or as necessity requires when there is accumulation of dirt in the nozzle. After each print, I immediately wipe the nozzle's outside, before it cools down. See my old (non-official) manual here: https://www.uantwerpen.be/nl/personeel/geert-ke
  5. I never tried burning out a nozzle with a flame. But I did try to burn separate pieces of filament in a metal spoon, in the flame of a bunsen-burner. I let it slowly heat up, and finally catch fire and totally burn up. The results were: - Both plastics melted into a bubbling pool of hot liquid. The PLA being more liquid than the PET, which stayed more honey-like. - Ultimaker PLA and colorFabb PLA/PHA filament burned-out into a thin layer of black dust, a bit like coal powder, easy to remove by rubbing. - PET burned-out into a thick layer of hard, black, glossy varnis
  6. If you are just beginning, I would say: start with small test pieces that complete quickly. Stay with the printer while they print, and carefully watch what happens. This is important to lear fast, and to react fast if things wouldn't go as expected. Try different overhangs, wall thicknesses, infil percentages, bonding methods (stay with the printer!!!), speeds, layer thicknesses,... Begin with simple models with a couple of holes, curves, extrusions, slight overhangs, and see how they come out. Start from standard profiles, until you get bonding and general things good and routine
  7. Another option that might work, is printing parts separately, and glueing? You are going to see the split lines anyway when you abort and restart a print. So glueing might do as well? For alignment you could make an extrusion on one part and a mating indentation on the other part.
  8. If the cookies or dough are soft enough, and if the cutter is open at the back so you can push them out, maybe you can get away with straight sidewalls, untapered? The constant width makes it easier to find optimal print settings. And then as desired go for single walled or double walled sides? A single wall has the advantage of easier cleaning, and no internal openings in which bacteria might grow. But it's weaker obviously. Also print rather slow and in thin layers, for smooth and strong walls.
  9. A kitchen sieve sounds like a good idea: if you take a bigger one, and 3D-print a custom clamp for it, the sieving-area is wide enough so that small particles getting stuck to the sieve won't totally block it. Mosquito-gauze (not sure of the name in English) for the windows might also work well. Easily available in brico-shops, and cheap; usually made of nylon here.
  10. I have heard about this method before, but never really seen it. If you have success, could you share a few photos of before and after, or treated/untreated next to each other? Is the effect more like acetoning ABS (high-gloss, very strong smoothing effect) or like acetoning PLA as cloakfiend does (satin, very mild effect)?
  11. The first photo looks like poor adhesion to the bed,. Maybe due to: - Nozzle too high? If so, adjust bed-leveling so that gap is thinner. - Dirty, soapy, oily bed? If so, clean with isopropyl alcohol, then with pure tap water. - Maybe other reasons? So I would first look into that direction. The second photo, I can't really say.
  12. If it was my core, I would probably: - first follow all guidelines on hot and cold pulls that I could find, - google for more info and videos, - then I would consider using a long and thin brass wood screw, to try to extract bits and pieces of junk. Or modify a brass screw, so it looks more like a drill bit. But it has to be a very soft brass, so it does not damage the inside walls of the nozzle. Maybe you need to find out how to soften brass first (maybe in a flame, and then slowly cool, I don't know?). Use it manually to get a good feel and go slow, definitely not an el
  13. I have no experience with the mould-option. But why not make the mould yourself in CAD? Then you have all the freedom you want, and you can insert any desired features. - Draw a box around your model. - Subtract the model from the box, so you have a hollow (mould) shape of the model. - Provide pouring openings and funnels. - Provide venting openings for air to escape. - Provide flanges or screw-openings to assemble and clamp both mould halves later on. - Design a thin plate and provide alignment features on the edges it: blobs on one side, pits on the other
  14. Maybe use a flexible PU coating? PU tends to glue well to most materials, and is quite resistant.
  15. Or replace an old cartridge just before it is empty, and test using the remains, then you don't waste less. Coating with non-stick teflon usually requires hot temperatures to bake it on. Otherwise you are back to oil-based teflon sprays... Depending on whether the 3D-prints are end-products, or intermediate, or tools like clamps, another option might be to make a mould from 3D-prints, and then pour a suitable material in it, for example silicone like used for mould-making and film-props. This is non-stick silicone that comes in various hardnesses, from skin-soft to tire
  16. 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?
  17. 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
  18. 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
  19. 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.
  20. 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
  21. If it is lost anyway, I would also try to disassemble it, even if only to see how it is made.
  22. 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,
  23. 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/
  24. 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.
  25. 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.
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