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Everything posted by geert_2

  1. In the older Cura-versions there was a setting "Combing" or something similar, which did exactly this: then the head would keep on already printed material, avoiding voids. I don't know about the most recent versions. Have you searched for that? However, this will not prevent blobs in some materials (the PET that I have): material is accumulated on the nozzle during printing, and then it sags and is deposited on the print in a thick blob. If this happens near the edge, is will spread outwards. So you have to post-process anyway with some materials.
  2. Maybe try pushing down the white ring with a suitable size hex wrench, or a ring or similar, so the load is distributed evenly on the ring? And then gently first push and then pull on the tube, and wiggle a bit? But always relatively gently. No brute force?
  3. To make removal of the clips easier, you could use these, or design a similar one yourself. Then it is piece of cake. For the model, see here (and then scroll down a bit): https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ In my own machines, I have a new design that is a bit optimised, but I haven't uploaded it yet. But I used these for 3 years; and they are reasonably good.
  4. That is nice. I could imagina this used for making emergency chalets, containers, caravans and other mobile homes. Lots of great application possibilities. How is water-tightness? (Important for boats and houses) I would like to see the boat in the water in real use. And how layer-bonding and strength, especially impactstrength? And resistance to sagging/deformation when the model is placed on uneven grounds? And how is the "filament" melted? Or do you use pellets, or liquids? I think a system with fast-curing composites with integrated mixing tip might also work: then the heat-problem would be solved, since it cures chemically. Similar to the dental mixing tips below (this is silicone, but they also exist for epoxies in other fields).
  5. Or you could design and print your own custom low-friction spool holder, for mounting on the back of the machine. My design will not fit your spools (it is for single standard spools only), but you are free to borrow and adapt the concept. It uses one standard 608 bearing (=also used for skater wheels). Design-files are in the rsdoc-format (=native DesignSpark Mechanical format), so if you have DSM you can edit them. Be sure to make it much stronger to support a large heavy spool. I also have an anti-unwind clamp that freely slides around the edge of colorFabb spools, to prevent the filament from falling off, and to clamp it while in storage. But there do exist lots of other designs too, often incorporated into the spool holder. It won't fit you either, but you can use the idea. See this page (and scroll down a bit) for the spool holder and clamp: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
  6. On my UM2 (single nozzle) printing in thicker layers reduces this effect quite a lot. But then of course you have more visible layer lines. So it depends on whether your application can have this. Maybe you could design a small test piece, but not too small so it still has enough cooling. And try printing that with different layer heights, orientations (for testing cooling flow), temperatures and speeds?
  7. For the spool holder with integrated balance: near the end of an old spool of stiff PLA, it may take 1kg (10N) to unload filament, to overcome the "spring effect" trying to wind it up again. Sometimes I can lift a nearly empty spool by the filament, without it unwinding. So, depending on the orientation of the pulling force, this might introduce quite big measuring errors, I think? This would especially be a problem where accuracy of the remaining length matters most: at the end of the spool. But at least this system provides a simple linear conversion between weight and remaining length, once the weight per meter is known. But this weight per meter would have to be changed per filament, otherwise printing with a metal-filled material might give unpleasant surprises. So it requires bookkeeping weights for each material and each color of filament (particle filled pigments like white might weight different from other pigments). For the geared meter: where is that supposed to go? This is not clear from the pictures or description. I guess it has to sit on the feeder, or on the filament entering the feeder, so it measures the length that passes by? Definitely not on the spool, due to the varying diameter of filament while unwinding. However, how does this system handle switching spools? I switch colors and materials maybe 20 times per spool, before it is empty. Then how is this meter going to adapt to this, without a complex manual bookkeeping and resetting? I think all this added complexity is prone to errors, and relying on it might cause more failed prints than just visually estimating the remaining amount, and using common sense. The best "guestimators" in complex varying situations might be humans. :-)
  8. I think they are going to be too stiff. And blobs, irregularities and print lines are not going to help making it water-tight. Unless you would squeeze it extremely hard between thick steel flanges. If you don't want to store gaskets, or originals can not be found anymore, I think you would be better off cutting new gaskets from a sheet, with a knife or a Dremel tool? Or use self-curing silicone or similar paste? For comparison: transparent PVC tubing for aquariums is much softer than TPU. But when I tried to use that recently to make a seal for my water-cooled disk grinder, I had a lot of problems getting it water-tight. Even the slightest amount of corrosion and oxidation on the surface of the metal, caused leaks. So, even soft PVC is not flexible enough to follow these tiny irregularities and close the gaps. But if you would try it anyway, let us know the result. It would be interesting to know.
  9. The thing is that a lot of spools are not transparent. They only have a small window, and they *do rotate*, and so does that window. So you can not see nor measure from the axial side how much filament there is still left on the spool. You would have to measure radially, thus from the top (sort of), and then calculated differences in distance by means of the reflected light, similar to a radar. And then calculate radiusses and circumferences for each winding, and the amount of windings. And then things soon start to get very complex. When you have spools that are very loosely wound, or materials that are very transparent, you are still likely to run into problems due to false measurements. So, a paper label glued to the spool, or moulded-in indicators showing the remaining amount, seems by far the most simple and robust, even though very crude. But then, I am a simple man, so I prefer simple solutions. If there are problems, I try to solve them by taking their complexity away, not by adding extra complexity, because then it soon gets too complex for me. :-) Anyway, I have never been confronted with this problem myself, as my prints typically require 3 meters of filament. So when the spool is nearly empty, I just unwind the last meters and let them hang free. Very easy to estimate. But I understand this is not practical for large prints requiring maybe 30 meter...
  10. I guess redesigning it to make it smaller is not an option, as probably some elektronics have to fit in? I would consider printing it in two parts, flat on the glass. But then it might be a good idea to have some overlapping areas in the side walls, if the design allows for it, so you can glue it better. See the pic below for the concept. Another option might be to print it diagonally on its side, from front left to back right, instead of slanted vertically? Then you only have to provide supports the top edge that is overhanging, and the bosses. To minimise the amount of support, and the damage it does, you could use free hanging supports like in the pics below. When printing like this on its side, you need good brim and good bonding, and then the whole thing still might get wobbly, depending on dimensions, wall thickness and speed.
  11. Multiple lines of skirt (=an outline around the model, but a few mm away from it) do solve the underextrusion due to the oozing before printing. I usually do between 3 and 10 lines of skirt, depending on the size of the prints: the most for small prints, the least for larger prints. I don't have problems getting them to stick, even if the beginning stutters a bit. Also, it gives you the opportunity to check if your bed leveling is okay, and it purges the nozzle and removes some of the dirt in the nozzle that often comes loose when starting a new print (=tiny black flakes in the melt). See the photos below. This is on UM2 printers, but it should also work for other models. (Note that these were testprints for trying-out bonding, overhangs and warping. Don't pay attention to any defects in these areas, but concentrate on the skirts, thus on the outlines around the prints: these are well printed.)
  12. Have you tried blowing the readers out with compressed air? Quite often there are dust and hairs accumulated in the slots, causing bad contacts between the cards and slot. This has helped several times for me. Do the printers fail on all cards, or on only one or two cards (but in all printers)? You could also have a bad SD-card, or a bad batch of SD-cards. Or you could have a program that has corrupted the cards. Or accidental corruption due to power loss or removing the card while writing to it. That sort of things. I am not saying these are the solutions (you may have bad readers indeed), but cleaning the slots and reformatting/replacing SD-cards would be by far the quickest and cheapest fix. If it works.
  13. I think so, otherwise the problem should have moved with the glass. So it must be or a bent bed, or incorrect leveling, or both? If you would have a steel ruler or a steel bar that is totally straight, maybe you can put that on the bed, and see if it gives perfect contact everywhere? Or does light shine under it in certain areas?
  14. What if you rotate the glass 180° (=front right becomes left back)? If the cause would be uneven thickness of the glass, the problem should move too. If the aluminum plate is bent, or leveling is the problem, then the problem should stay in place.
  15. When reading my text again, I see that it could be interpreted in multiple ways, and it was not clear enough. I was not trying to convince you to switch to PET. :-) But I was wondering if the same principle that I use for PET (=printing very slow, very thin layers, very cool) would also work for your ASA materials, if you have tried that?
  16. These photos show the effect of acetone on a part that I left on purpose in acetone for way too long (more than an hour), just to try what would happen. It got weak, lost its spring-effect, and cracked. Its strenght recovered somewhat in the next months when drying, but not fully. Now I broke it. So you can see how deep the acetone penetrated and cracked the model. The inside seems to be still chemically affected, as it broke in a weird way, with very different inner and outer fracture surfaces. This is yellow PLA/PHA from colorFabb. The fracture surface is ca. 6mm x 4mm.
  17. 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 below the recommended minium, the material does not decompose too much in the nozzle, even though it is sitting there for a longer time. When these models break, the fracture goes diagonally through all layers, as if there are no layers. Absolutely no delamination-effects, which indicates a good bonding. See the photos: the fracture lines start at the bottom center, and then radiate outwards in a star-pattern, regardless of layers. This is clearly visible under a microscope, but hard to photograph. Layers are very lightly visible too, running vertically in these photos. This model is ca. 6mm x 4mm cross section. It might be worth trying this too? The main disadvantage is of course that it goes very slow...
  18. 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.
  19. 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.
  20. 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 blob, so it is not dragged around. It is made from rustfree spring steel, the sort that is used in dental applyances. Very hard to bend in shape, but once bent, it keeps its shape very well, and it stays clamped to the frame. Due to it being a spring, it scrapes the nozzle and then moves down, without hurting it. See the photos from different angles below.
  21. 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 should have been standard on all spools, since it can easily be injection moulded into the spool. But I don't remember that guy's name. Maybe you can find that thread for ideas?
  22. 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.
  23. 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).
  24. 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. Multiple test blocks together: layer heights from left to right (mm): 0.4; 0.3; 0.2; 0.1; 0.06 (nozzle 0.4mm). Top row printed at 50mm/s; bottom row 10mm/s. So, thin layers and slow speeds give very high density. But you need to print at the lower end of the temp-range, otherwise the material starts to get brown and decompose due to sitting in the nozzle for too long.
  25. 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 essential life-liquid in normal quantities. Breath-in 100% of N2 gas (nitrogen) and you fall dead immediately, in a few seconds, because in the absense of oxygen the nitrogen binds with the hemoglobin irreversibly. I had collegues die in this way 30 years ago. Even though there is 78% of N2 in the air. Same with other essential stuff. Further, in the absense of reliable source-info, or in case of conflicting info, as on this subject, I always try to go back to basic and well-proven scientific laws of chemistry, physics, biology, biochemistry, electricity, etc. I try to do the math myself. And I try to look directly at nature as much as possible. Not via-via-via filtered info in the press which may have an unknown agenda. Also, directly looking at applied technologies and machinery is a good way to see if the basic concepts on which they are based do work or not. The fact that a machine works, proves that it is based on at least partially correct principles. This is what I tried to show in the above text.
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