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Everything posted by geert_2

  1. I have no solution for a smooth bottom plate on top of supports, for a single-nozzle printer (like my UM2). The underside where the support was, is always a bit rough. Except design changes: cutting the model in half, printing both halves on their flat cut side, and glueing both parts together afterwards. But you will see the seam. Or making the model asymmetrical, so that one side can be laid flat on the glass without need of support (if the design or function allows this). I once made testpieces for supports to try to minimize this roughness, and still be able to get
  2. The PET I have does similar things: - While printing, it accumulates on the nozzle. This goo then gets brown, and sags onto the model, and is deposited as big brown blobs. The brown color is clearly visible on white, but it may not be visible on black. These blobs also tend to cause fine hairs in the print, both when the blob sags from the nozzle, and when the nozzle passes through previously deposited blobs. - When bridging, it does not pull a nice bridge. But the strand rather tends to snap like chewing gum and fold back onto itself, causing a blob under the nozzle. This is
  3. Yes indeed. My models typically take 2...3 hours to print; I rarely have longer printing times. So I don't know how it would hold up for long prints that take a day.
  4. Yes indeed, "insect antennas". I see this on PET too. Printing slower and cooler helps a bit for me, since there is less pressure build-up in the nozzle, and it leaks less. But I don't know a way to eliminate it.
  5. I print PET on clean bare glass. Sometimes I use the "salt method", however this does not increase bonding for PET (contrary to for PLA), but rather reduces it slightly, but it makes it a lot easier to remove parts. To prevent warping, I use no cooling fans, or the absolute minimum. But no fans makes it more difficult to bridge gaps, so this is not suitable for every design. Most of my designs are long flat models without bridges. I tried dilluted white wood glue too a couple of times (ca. 10% glue in water), but this bonded way too strong: it tended to chip the glass while cooling
  6. What about changing your bonding method, so your prints can be removed easily? For PLA, I use the "salt method": wiping the glass with a tissue moistened with salt water, prior to printing. No glue. This gives good bonding while hot, but absolutely no bonding when the glass is cold. So, models can be taken off very easily. But this is only for PLA, and for low flat models (not for "lantern poles"). For my old manual, see here: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ User neotko uses hairspray for bonding, and he removes his models by adding a few
  7. Another trick is to model in your CAD design a few dots outside of your model, sitting 1mm lower than the real model. So Cura will drop the dots onto the bed, and then the real model will float 1mm above the glass. This of course will require you to use supports for the floating part, otherwise it will print spaghetti.
  8. I guess the snap-areas are the two "keyhole" openings? First I would make the splits a bit wider, so the clamps would deform less while snapping over the rails. That should still give enough retention. Depending on the load it has to see, I would also use a higher infill, maybe 50...70% or so? And the layer-lines should definitely go in such a way that they cause no weaknesses. Just like when you cut wood along the grain. You also need to print hot enough, and slow, to get a good layer-bonding and no underextrusion. Personally, I have no problems with PET sn
  9. For my (older) UM2 and PLA and PET materials, 25...30mm/s is slow enough to get good quality. At 50mm/s (default for PLA) quality is okay for most models, but not optimal for high details. Printing at 10mm/s is too slow: then the material is sitting too long in the nozzle and it starts to discolor and decompose (gets brown). It also depends on the temperature. Lower speed gives less ringing, cleaner corners, and better layer bonding. I would say, make a small test model with your typical features, and print that at various speeds and temperatures, and closely watch what
  10. Some materials do not print well over gaps: instead of pulling a nice string, they snap and fold back into a blob on the nozzle, thus effectively printing nothing, and not closing the gap. That blob is then deposited on the next wall the printer encounters, causing a weird sort of "insect antennas". Could it be that you have this effect too? In addition to the fact that you are not printing diagonal lines over the gaps, but concentric lines, which have nothing to hold onto.
  11. Hello, During the years the site has been getting better and better, so this is a good evolution. But I think it could still contain a bit more diagnostics manuals and tips and tricks that come back very often in the forum. For example: - A detailed list of all existing and well working bonding methods to the glass bed: the "official" glue stick, the official glue stick + wiping it with a wet tissue to egalise it, 10% wood glue in water, hairspray, my salt method (PLA only), 3DLAC, sheets, etc... With all their advantages and disadvantages. So that people can try them, and cho
  12. Yes, obviously an atomic pull by rotating and wiggling is not going to work on split channel nozzles. :-) At the time of writing that manual, I didn't even know such nozzles did exist. For temperatures, I think the best is to try lowering and increasing temp in steps of 5 or 10°C on the fly, while doing a testprint. And then see when it starts to underextrude, or get too liquid. And then find something inbetween that works best for your typical models, speeds, materials, nozzle, and printer model. All these have an influence. Start from the default values for your situation.
  13. Maybe you could circumvent this by adding four little dots of 1 layer thick in the corners, outside of your real model? So they define the borders? And always keep these dots in the design?
  14. @silver-girl: are you sure you have a standard nozzle? I think there are a few printers with split internal channels in the nozzle, like a snake-tongue. Maybe you have such a one? Standard atomic pulls should look somewhat like these below. Here the big blob in the white indicates that the teflon coupler (UM2-printer) is worn out (=internally deformed) and needs replacement. The orange at the bottom is what an optimal result should look like. Orange/white colors shades are due to doing the atomic pulls as part of a filament color change.
  15. Usually I do the cleaning with desinfection alcohol (I think that is 70% isopropylalcohol + 30% water?), then clean again with pure luke-warm tap water only. Then prior to printing, I wipe the glass with a tissue moistened with salt water. This leaves a thin, almost invisible mist of salt stuck to the glass. This greatly improves bonding for PLA, compared to printing on bare glass, as long as the glass is warm (60°C). After cooling down, models pop-off by themself, and there is zero bonding. So this method does not damage delicate models. After that, I just re-wipe the
  16. If you have an oven, for example to dry filament, you could also pre-heat the cleaned glass in there. This should reduce the warming-up time a bit. This is just a theoretical idea :-) I never tried it myself, since I never take the glass out of my printer: I let it cool in the printer until the models pop off, then wipe the glass with a tissue moistened with salt water, and start the next print.
  17. Have you checked these? - Check if the little nozzle-cooling fan at the back of the head still works? If not, or if too slow, this would cause the heat to travel up into the filament, soften it, and make it hard to get through the teflon coupler. Sometimes filament strings and hairs get sucked into it, slowing it down. - Does the feeder wheel not slip on the drive axis? Write a colored mark on both, and see if they stay aligned? I have read that this occasionally happens. - With a fine needle (with rounded edges so you don't damage the nozzle) gently and car
  18. From the gcode, can you write text to the LCD-display? If yes, you could insert status messages every few lines in your custom code, and then let it wait for a second (so you have time to read), before doing the next command? Might make debugging easier.
  19. Ask Simone Gierz, she can definitely make one for you. :-) See her TED-talk: https://www.youtube.com/watch?v=c0bsKc4tiuY
  20. Dental composites are extremely hard; these are the white fillings. They are particle filled (=sort of sand), methyl metacrylate based epoxies. But they are also extremely expensive, and light-cured, so you need special equipment (blue power-LED) and thin layers to cure it. And you need water-cooled diamond disks to cut and shape it after curing, you can't get through with a knife or steel bit. So these materials are not practical for other uses. But maybe you could simulate this concept? Print a mould, coat it with release spray, and then fill it with a mix of fine sand and epoxy?
  21. I don't know much about gcode, and even less about firmware, so this is just guessing. Could the problem be that "padding thing", that you see earlier in the gcode, at the end of the normal file? Try copying and inserting that padding at the end of your push-off sequences too? Apart from that, I think any resetting or homing is done at the start of a new print job, just like any normal print. In normal use an UM2 can start from whatever situation it was left in (warm/cold nozzle or bed; head or build-plate sitting anywhere), so that shouldn't cause problems I think?
  22. Maybe just remove the filament, so it "prints" empty?
  23. The brown spots on your print - if they got there while printing (not afterwards due to post-processing) - are likely material that got accumulated on the outside of the nozzle, then partially burned or decomposed, sagged and got deposited on the print. Or material that got partially burned inside the nozzle and then extruded. If your purpose is to make a model as a base to create silicone moulds later on, I would also recommend trying PLA. I have good experiences with Ultimaker Pearl PLA, and with colorFabb red and orange PLA/PHA. And smooth this later on, so the mould is smoother
  24. If you are not sure it will print well, maybe in CAD you could cut out a small area of the top-side (=with the red faces). Just a tiny cube that has all the problem-aspects? And print only that, and refine settings if required? So you don't waste too much material.
  25. I don't know this material, but if I would see this effect in PLA on my UM2 printers, this would be overextrusion. Is there a specific reason why you prefer ABS? Because it is known to be more difficult to print than materials like PLA, tough PLA and PET. (Although PLA can't handle warmer temperatures, and PET is more difficult to glue and paint than ABS.)
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