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Everything posted by geert_2

  1. I don't have this material, but my experience with PET is just the opposite. On my UM2-printers, I achieve the best bonding and best fill rate (=least amount of unwanted voids inbetween extruded sausages) at very low speeds, thin layers, and low temperatures. Typically 20...30mm/s; 0.06...0.1mm layer height; 210...215°C nozzle temp; and no fan (!). Due to this slow speed the material has plenty of time to melt and bond with the previous layer. Due to the thin layer, the heat from the nozzle is transferred well onto the previous layer. And due to the low temperature, even 5...10°C b
  2. Thanks for showing the idea. I have seen this concept for embedding nuts, but I hadn't seen it for other stuff like reed relays, sensors and magnets.
  3. I don't know what printer that is, but to me it looks like or bed adhesion is not good enough, or the nozzle is too far away from the bed. Then for small circles it tends to pull the printed string off sideways. Just watch closely what happens when printing.
  4. Whether you use a prime blob or not, I think it is a good idea to use a few lines of skirt anyway. This gives an indication if your bed is calibrated at the correct distance, and you have time to manually adjust it if desired (at least on UM2 printers, I don't know about others). You also have an indication if bonding is okay: if the skirt would already fail to stick, the rest will too. And finally, if the nozzle is getting dirty, tiny flakes are often released in the very beginning, showing up in the skirt. Also, for my UM2 printers I added a wire to catch the priming
  5. The problem is that systems with sensors and wires on rotating stuff are prone to all sorts of errors: false positives, and not correctly detecting real amounts, due to the spool rotating and the "sensor window" being covered by that rotating spool. These things will complicate the situation. But recently there was a post of a guy who printed labels with a measuring scale showing the remaining amount. Then he glued the labels to his spools. The idea was similar to the scales on glass bottles and measuring jars in the kitchen. This actually is a nice and simple solution, I think. It
  6. Interesting. And how is layer adhesion? Can you pull layers apart, or is it melted into one solid block? PS: I think the word for half-transparent is "translucent": when some light is still shining through, but it's not water-clear. Like the model below (this is colorFabb PLA/PHA, "natural"), which looks like uncooked spaghetti.
  7. This is what I standardly get by printing on bare glass (0.4mm nozzle). The lines are visible, just like they are visible in injection moulded parts where material flows meet, but the indents are very small. The overall appearance is high-gloss (see the lower half of the first photo: here I focused on the fan cover mesh reflected in the bottom).
  8. If you print slow and with thin layers, so that it flows well into all corners, then density is already quite high with the current 90° alternating strategy. For example with 0.4mm nozzle at 0.06mm layers. I don't think density can be improved very much. However, at high speeds and thick layers, there are a lot more voids. See the test blocks below of 10mm x 10mm x 20mm. The front one is as printed, the back one is polished to remove some of the outer layer lines and show the inside. The clearness indicates that there are not too much voids inside. This is transparent PET.
  9. Yes, I can see what you mean. It is a matter of quantities indeed. I'll mention that aspect in further texts. Maybe I should have said: "CO2 is a life gass, and no poison at all in normal and slightly elevated quantities". About 0.3% (=10x more than the normal 0.03%) is still almost nothing. In poorly ventilated classrooms the concentration can be much higher than 0.3%, and we are all still alive. But in too high quantities it can kill indeed, just like almost anything. Drink 10 liter of water in an hour, and you are dead due to water-poisoning. But water is an essentia
  10. Randen van overhangende delen hebben de neiging om op te krullen, waarna de nozzle daar met geweld tegenaan kan botsen. Deed zich dat hier ook voor? En dunne paaltjes gaan soms wiebelen. Verder: kijk eerst eens in Cura met transparant view en x-ray view of er geen defecten in het model zelf zitten? Indien het okee is, probeer dan eens in een ander materiaal te printen? Gewoon standaard PLA of zo. Dit lijkt een "filled material" te zijn, dus met partikeltjes, en die zijn meestal veel brosser dan gewone materialen. Kan je de afgebroken paaltjes manueel makkelijk verder br
  11. Concerning plastics burning: some burn very dirty indeed, especially ABS and PVC. But some burn very cleanly, like PE, PP and PLA, releasing almost nothing but CO2 and H2O into the atmosphere. Such exhausts can easily be filtered with equipment similar to the filters and catalysers in cars. Concerning the effect of CO2 on plant life: you will find lots of sources if you Google for: - plant growth versus co2 level - real co2 science CO2 is the bubbles in sparkling water, cola and beer. It is the bubbles in bread. It improves the working of our stomach. And it i
  12. Thanks, good idea. I have seen the concept before (metrinch wrenches in shops), but never tried it in 3D-printing. Do you have a rule of thumb, or a formula, for designing the optimal curves? Or do you do it just visually and based on experience? This isn't a standard shape in my 3D-editor DesignSpark Mechanical, so I will have to draw it manually. This concept of "recessed corners" (I don't know a better description) could surely help to reduce the accuracy problems in corners due to ringing, thickening and rounding effects. Also in other designs. Maybe the original po
  13. Something that just occured to me: if you are going to recycle spools by sending them back, it might cause way more harm than it solves. You need to pack them into cardboard boxes, and stuff the box with thick shock-absorbing paper or cardboard. This requires cutting down trees to make cardboard. And it requires a lot of transport: if you are going to have DHL drive 20km to collect your packages, that comes with an environmental cost too. The cleanest option is to re-use them at home, or for your neighbours. Apart from that, I think throwing them in the regular waste co
  14. Layer lines, blobs, strings, hairs, ringing and thickening at corners, always cause inaccuracies. I usually make a couple of small test models to try which tolerances work best for a particular model feature. Depending on the required fit, I usually take between 0.1 and 0.5mm tolerance for my UM2-printers. Printing slow and in thin layers also helps. For example for inserting M4 nuts (which have a diameter of 7.0mm between flats for steel, and 7.2mm for nylon, in my inventory) into a 3D-printed cage, I made this test model with 7.2, 7.3, 7.4 and 7.5mm hex cages. Then I tried what worke
  15. An option you could consider is to design part of the supports in CAD, in the same material as the model. And make these as efficient as possible, and as sturdy as required. But leave a gap between the support structure and the real model, don't connect them. And then let Cura fill-in that gap with its automatic supports. You could design a dove-tail on your own supports, so that Cura's PVA gets a good mechanical grip on your custom support. I am not sure if this would work well (I only have single nozzle UM2-printers), but it might be worth trying? Anyway, I usually de
  16. In moist weather, printing on bare glass didn't work at all for me, in the beginning. Neither did the glue stick (but looking back, I think I used way too much glue). That is why I developed my "salt method": after cleaning (only alcohol, no detergents, no soap!!!), then wipe the glass with a tissue moistened with salt water, so there is an almost invisible mist of salt stuck to the glass plate. For PLA this greatly improves bonding when the glass is hot. But there is no bonding at all when cold, so this makes model-removal easy. For the full manual, see here (and then scroll down
  17. I only have single nozzle UM2 printers, so in my models everything is in the same material anyway. I need to remove these supports manually by cutting or plying. That is why I design-in features to make their removal easier (such as the ribs on top of the support). Everything, also all custom supports, are part of my CAD design, and I switch off any support in Cura. For multiple nozzle printers (UM3, S5), I think in Cura you can assign different nozzles (and thus different materials) to different parts of the model. But I don't know how, so I will leave that to others here. But as
  18. I don't see how vibrations could cause this? Unless there would be some mechanical defect, such as motor, gears or belts being blocked or so dirty that it hinders their free movement. This could cause abnormal sounds indeed. But a sort of "robotic singing sound" in diagonal lines is normal. On the condition that these are not the very first layers on top of empty gaps (above infill or hollows), as Smithy says, I would guess: underextrusion, too low temperature or too high speed, not 100% infill selected (e.g. 90%), too much friction in the filament or feeding traject, dirty nozzle
  19. Exactly. This is why I don't want any online CAD service for production work. You never know when a company is bought by another and when their management and policy changes. Also, you never know if the internet would go down due to technical reasons (fire, storms, cable fracture,...), or their service provider goes bankrupt (=servers that host the software). Or, if their servers are in California, when incompetent or corrupt electricity companies shut down their high-voltage lines and 110V/230V mains due to forest fires. Like very recently when they shut off a million
  20. Once you get your bonding method right, most of the time you can print directly on the glass, using that bonding method. No need for raft. This should also give a much smoother bottom side. For special models, an option is to design custom brims or supports into the model in CAD, so they are part of the design. In this way you can enhance bonding where necessary, without affecting other parts. For example in the model below, the cube (right) has a custom brim, to make sure it sticks well. Also the pink and orange supports have a custom brim, for more adhesion. Otherwise
  21. What I would do: print slow and in thin layers, so that the molten material has plenty of time to flow, and to make a good bonding with the previous layer. But print at the lower edge of the temp-range, otherwise the material may decompose due to sitting too long in the nozzle. Make multiple walls, or make the walls so thick that the whole part consists of wall, instead of infill. Use a single nozzle, so you do not have PVA stings going throught the PET, leaving a hole after dissolving the support. These models below are in PET. They are not hollow (except for the watermarks), but
  22. I also use DesignSpark Mechanical since several years. Its interface concept is close to that of SketchUp, and easy to learn. I never had any software problems when printing these designs (except for my own errors and omissions in the design). As said above, view a couple of Youtube tutorials, and see if it appeals to you. Also do this for other programs on your maybe-list.
  23. Also check if the filament is not bent (like in a knot), and not tangled or wrapped under itself on the spool. I have had these two things causing problems too, and they can easily happen if you frequently change filament.
  24. I use them for winding-up electric cables, and laboratory silicone tubing. Also see my reply here: https://community.ultimaker.com/topic/29827-recyclable-spools-for-ultimaker-printers/?tab=comments#comment-248753
  25. If the bottom is flat, then as Didier Klein said, I would also print this on the bare glass. Without raft. This gives you a smoother bottom-surface too. For better bonding to the glass, I use my "salt method" (see this page, and then scroll down a bit): https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ Other people use dilluted wood glue, hair spray, glue stick, glue stick + wiping with water, 3DLAC, etc. So, plenty of bonding methods that should not cause this sort of issues. I would suggest you try them and find one that suits your models, and that y
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