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geert_2

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Everything posted by geert_2

  1. Is this a Z-seam issue? It rather looks like underextrusion to me? Just a guess, I don't know your printer. Generally, printing slow, in very thin layers, near the lower edge of the temp range (=to prevent overheating and decomposing of the filament, due to sitting in the nozzle for a long time), tends to give the best results, in my experience. Also, in addition to the above suggestions, set all speeds to the same value (inner and outer wall, infill), so that the flow through the nozzle is as constant as possible. Wild speed variations cause wild flow variations, and thus temperature variations, and a lagging in nozzle pressure (=overpressure at the end of a fast traject, and underpressure at the start of it).
  2. That is a really nice, shiny color. What filament is that? I vaguely remember a post that said that some such shiny colors were much more difficult to print than standard PLA. So, to filter out the cause a next time, you might want to try the same model with regular PLA. Then at least you know whether it is the model or printer, or the filament. PS: for your Google Chrome problems: try using another browser: Firefox, Pale Moon, any others? Although Firefox too has sold its soul to Google. It appears that Google was from the very beginning a CIA-project, designed to infiltrate and spy upon as many computers as possible, worldwide. And then to censor anything their masters didn't want us to know. They did that very well, I must say, and we all fell into the trap, me too. Now they are even censoring innocent things and proven science and technology. But don't believe me, try to check it for yourself. Just don't use Google as your search engine for this, because it censors everything... Instead, try DuckDuckGo, Yandex, Searx, Qwant, Swisscows, or so.
  3. Your model defects look way too nice and too regular for "stringing". So I guess it is a defect in the model. This happens all the time with models made in SketchUp, and it also seems to occur with Blender models and some other editors that were originally developed for visual 3D-modeling (like games, simulators, animations, 3D-art). These editors often produce a sort of "cardboard" 3D-models with seams along the edges, and with duplicate surfaces, etc. Models for 3D-printing however do require solid, water-tight models, without any seams, without duplicate surfaces, without internal surfaces, etc. The models should be like a solid block of iron, instead of glued together cardboard. Real stringing looks like very irregular strings or hairs, when the nozzle is leaking while traveling through the air between different areas. Thick strings usually come from material leaking out of the nozzle (=from the inside), and thin hairs usually come from material accumulated on the outside that is sagging and touching other parts, and then pulling a hair. "Insect antennas" come when a leaking drop is deposited onto the next item the nozzle encounters, after traveling through the air. On the following pass, the drop is deposited onto the previous drop, and so on, causing an upwards growing insect antenna. This pic shows stringing between both pilars, and sagging (like spaghetti) on each pilar, while printing free-hanging supports for a bridge that has to come between the two pilars. This pic shows a little bit of stringing on the top cones, and sagging below the long unsupported overhangs. This are "insect antennas" and strings and hairs.
  4. No experience myself. But when looking at pictures of dual-nozzle, dual-material prints, we often see tiny strands of material 1 embedded in material 2. The same hairs and string that we see on single nozzle printers, and that we wipe off or cut off. But then unremovably embedded into the other material. So I think there is a high risk of short circuits. In addition, it would be suitable for high-impedance applications only, like anti-static. It would require quite a lot of testing and fine-tuning, I think. Unless you would print the conductors and insulators separately, clean them up, and glue them together. I could see that working in let's say model railroad trains and houses. Or in low-voltage touch sensors, or so. If I remember well, this has been discussed a couple of years ago? Maybe you can find that post again? It might be outdated, but maybe there are still good tips in it?
  5. See the recent topic on "theory on warping", or something like that, where we discussed possible causes. I guess your environment is way too hot now, and the print stays soft and peels off.
  6. What I meant was this concept: This has a flat bottom to print it easily. And the print-lines will follow the curve and be much stronger, instead of being perpendicular and weak due to poorer layer-adhesion. Yes, the front plate (the label area) might be a bit rougher than if it was sitting on the glass, so it might require a quick sanding, or a quick chemical smoothing, depending on the marker you use for writing. But I think in general this would be much stronger and longer lasting.
  7. I would use PET for this. Indeed, PLA tends to get hard and brittle, and to creep-deform, losing its clamping force. PET can handle this much better. Also, PET won't deform so easily in summer, or when sitting behind the window in the sun, of when left in the car. PLA will deform in a car, even in a mild spring or autumn sun. But I would recommend that you modify the design: cut off a piece of the bottom, so that it becomes one big flat plate, and you can print the whole arc flat on its side. This will print faster, cleaner, and much stronger, because the print-lines will follow the curve. If required, enlarge the height of the label-area upwards, if it needs to have a certain height, e.g. to fit Dymo labels. PLA (left, cream) deforming and cracking after some time, PET stays in shape better: Recommended concept for clamps and labels: flat bottom plate for a stronger clamp, you get the idea:
  8. I don't know your printers, so I can't say much about that. I guess you will have to compare all other settings too, one by one? Printing speed, nozzle temp, material flow, double-check fans, other airflows,...?
  9. Yes, feel free to try variations on this test model. My guess is that 1/4th is going to fall over easier, but this in itself is also a good test, of course. Tiny holes are more difficult to lay down the first layer: the strand of filament tends to be pulled off towards the inside of the hole. I had that in the beginning with my typical models with lots of holes (see pic below). However, after I decreased the nozzle-bed distance, and after I started using the "salt method", I have never had this issue anymore. The "salt method" is: wiping the glass with a tissue moistened with salt water, immediately prior to starting a print. This leaves a thin mist of salt on the glass, increases bonding of PLA a lot, compared to printing on bare glass. As long as the bed is hot, models stick well. But once cold after completing, models pop off by themself. You can see the salt on some pictures above. My "salt method" works very well for long, low models like rulers (see pic below). Thus 99.99% of the time I only use this salt method, without any glue. Picture: typcial model with lots of holes (for reference: embedded watermark ruler is in mm). Also, high but thin models like lantern poles are hard to print. They do not really warp, but they get knocked off the bed easily, due to the long lever-action, even with a brim. This is where a thicker custom brim is usefull too. The salt method does *not* work well here: you would better use glue, which has a bit of elasticity and can absorb shocks better than salt. Picture: model knocked off the glass, due to long lever-action (high model and small base), plus overhangs that severely curled-up (more than 1.5mm), so the nozzle hit them very hard when traveling from one part to the other. Also notice the salt on the bed. Less curling-up after changing printing settings, so less knocking-over, and the model could be completed. (This was a bridge test with hanging, removable supports.) So this is on the edge of what the salt method can do. In my experience, big chamfers and roundings at the bottom also decrease bonding, and thus increase warping. As do single-wall hollow objects. In both cases, the bottom layer is peeled off the glass, sort of. That is why I developed the "inverted prism" test, it is a hard test. A thick bottom layer of 0.3mm reduces contact area and thus bonding: the strands are too round. A very thin layer of 0.1mm is difficult to lay down evenly. I get best results with 0.2mm first layer. Printing this first layer too cold also reduces bonding and increases warping. Idem for insufficient priming of the nozzle. So, the first layer should be squeezed well into the bed, printed thin, hot and slow, after good priming with a skirt or brim. Years ago I did some tests on the effect of bed temperatures on bonding and warping: lower bed temperatures reduce warping a lot, because the plastic is much stiffer and further away from the glass transition temperature. But a lower bed temp also reduces bonding a lot, so the models tend to pop-off suddenly with a loud plop in mid-print. Higher bed temperatures increase warping and thereby also reduce bonding: the bottom stays too soft, and it is peeled off the bed very gradually. This is what you see in the red test pyramid above. For PLA, there is a sweet spot inbetween these, where bonding is still good, and there is not too much softening: around 55-60°C. Below 50°C bonding is too poor, and above 65°C, models peel off and sag and get elephant feet. (This is in my experience, but this may differ from PLA brand to brand, and depend on circumstances and bonding methods, of course.) Near the edge of the glass, temperature can be a lot lower than in the center. This can also reduce bonding and thus increase warping near the edge. Idem for small models printed with 100% cooling fan: this cold airflow cools down the glass locally with 10-20°C. Moist air also reduces bonding, and increases any tendencies to warp or to come loose. Very dry air like in freezing winter weather, improves bonding, or at least does not reduce it. Poor bonding in rainy weather is what initially prompted me to test bonding temperatures and methods, and why I developed the salt method. See here for my old manual on the salt method: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ So tendencies to warp, or to come off the bed, could be a combination of all this: - tiny contact area, compared to model-size ("inverted prism" shapes), - big models filling the bed, - chamfers, roundings, overhangs, at the bottom of the model, - thin high models, - tiny holes, - single-wall, hollow objects, - too thick bottom layers, - nozzle too far way from bed, not enough contact area and squeezing, - too low or too high bed temp, - too low nozzle temp, - too high printing speed, - too much local cooling, fan blowing too hard, - moisture, - non-optimal bonding method for the material, - other things I forget? The default settings in Cura take care of most of the machine-related issues.
  10. Thanks for this close-up of the trim line. Indeed, I was wondering how you could easily cut off such 1mm thick ears. That is why I was limiting myself to 0.3mm - 0.5mm custom brims, the maximum I could easily cut through. I am going to keep your solution in mind for future critical designs.
  11. Are you sure you used the same material in both printers? PLA bridges quite well and pulls nice strings that do close the gap soon. But PET and similar materials won't: the string snaps and folds back onto itself, causing a blob instead of a bridge. This makes it a lot harder to fill the top layers, especially when the cooling fan is off for better layer adhesion. Also check cooling settings and cooling fans on both machines.
  12. @GregValiant: a question, out of curiosity: is there a special reason why you made the elephant ears 1mm thick? When I design custom brims, I usually make them 0.3mm to 0.5mm based on gut feeling, but I have never tried 1mm. The standard single-layer brim in Cura is sometimes too thin to keep a stubborn model down.
  13. An inverted prism reliably causes severe warping, in all aspects: warping due to insuficient bonding to the glass, and warping due to steep overhangs. This shape has a very small bonding area to the glass, and huge overhangs that do cause huge shrinking and warping forces. This is a very hard test: due to warping of the overhangs, they do curl up, and then the nozzle hits the curled-up edges very hard, knocking the part loose. I used that as bonding test in the beginning. To prevent the prism from falling over, I used a cross of two prisms, instead of a single prism, and I added a bigger patch in the center. Different bonding methods, printing-speeds, layer-heights, temps, materials and colors all have an effect on the warping, curling and bonding. Pictures: This one sticks pretty well to the bed, without too much warping (just a little bit at the left): The basic concept: two inverted prisms, plus a central patch: Testing the effect of custom skirts on warping and bonding. The idea was to minimise cooling of the glass due to fans blowing, but it didn't make much difference: Severe warping from the bed, plus edges curling up, and nozzle banging into them (but this print could still be completed, although barely): Bottom-view of another testprint, showing some warping at the edges: Cross section. Main dimensions: contact area at bottom = 2mm wide; top = 10mm wide; height = 5mm; bottom-length = 45mm; top-length = 50mm: If you would want even more warping, you could always make the prism top (=pointing towards the bed) smaller, so there is less bonding area. In my experience: - thick layers = more warping from the bed, but less curling-up of the edges - thin layers = more curling-up of the overhanging edges, but less warping from the bed, and better accuracy STL-file: warptest11.stl
  14. Horizontal lines often occur when the area to print suddenly changes per layer, especially on small models. You also see that in most boat-benchies. I often see that in my small models. But I don't know if that is the cause here. Another reason could be if the slicer changes direction from clockwise to counter-clockwise (if they do this, I don't know). Maybe you can see what exactly happens when watching closely?
  15. I can read German, but can not write it good enough, so I 'll write in English. In my experience, small and thin black flakes usually come from the inside of the nozzle: stuff that has baked onto the inner edge of the nozzle, or from between the connection between nozzle and teflon coupler (UM2). But bigger, light brown blobs of goo usually come from the outside of the nozzle. Especially with sticky filaments like PET. (I haven't printed with nylon yet.) While printing, that sticky material also accumulates on the outside of the nozzle. Due tot the long baking time, it decomposes and gets brown. After some time when enough material has accumulated on the outside, it sags down and gets dropped onto the print. Watch closely while printing, and you can see it happening. Printing slower and cooler reduces the effect, but does not eliminate it. So I would think that the big blob in your photo is from the outside of the nozzle, not the inside. Wiping the nozzle immediately after each print completes, also reduces the effect. You don't want a dirty nozzle covered totally in goo. And indeed, treating the nozzle with oil also helps. I occasionally do this after a torough atomic pull. Treat both inside and outside of the nozzle: inside by gently sticking a copper rod dipped in oil into the nozzle from above. Outside by wiping with a leather tissue soaked in oil. Obviously, cover the glass with old newspapers first, so no oil drips onto the glass, otherwise you have trouble bonding. Then let it sit at 200°C for a couple of minutes. And that's it.
  16. Generally, printing as slow, cool and in thin layers as possible, improves quality. But obviously, it also increases time quite a lot. In CAD, cut out a small part of this model with complex features, and try different settings on that, so you don't waste days on a full print.
  17. I have never done this myself. But here on the forum I have seen people embedding things in the following way: - design the model, with a hole where the embedded part has to come later on, - start the print, and let it print to the top edge of the hole, - pause printing, - drop in the embedding, and glue if required, - continue the print until finished. Obviously, the last printed layer before pausing and embedding, must be a bit higher than the thickness of the embedded thing, so the nozzle doesn't hit that embedded thing. This works well for metal plates, coins, and similar stuff to embed. Not for irregular shapes with undercuts that need a tight fit. You can't embed a statue in this way, obviously. For such irregular parts, I think printing multiple parts and then glueing or bolting them together might be a better option. Or print the outer shell, and a sort of inner clamp for the embedded thing, and fill the rest with an epoxy (low exotherm!) or gypsum. If you only want to print on top of a foreign part on the glass, thus not really embedding (surrounding) the part, a trick for offsetting might be this: - let the object to print float in the CAD model, at the desired height or offset, - outside of that object, print a few dummy parts sitting on the glass, thus with offset null. These dummy tiny parts will prevent the real model from being dropped onto the glass, so it will print at the correct height. How to center all, is another question: then you would need to include a few outlines where the thing to embed has to come. After printing this bottom layer, pause, glue the embeddings in the right place, and continue. Maybe something along these lines?
  18. Yes, with that tiny size you won't get far with a cord, indeed. I did not realise it was that small, I thought it was a regular size belt. Probably print even slower? And adjust temperature down, maybe to well below recommended minimums, so the filament does not burn inside the nozzle due to sitting there for too long? And of course the thinnest layer height. For printing accurate PET models, I have gone down to 10mm/s speed, 0.06mm layers, and 10°C lower than minimum temp range for that material. But I don't know if that would work for TPU too? The idea behing printing slow is that there is very little pressure build-up in the nozzle, thus the flow accurately matches the model, and the filament has plenty of time to melt. But at the normal temperature, it might degrade, decompose, or burn. At least, this happens with PET and PLA, I don't know for TPU. So that is why you also need to lower temp, to below its decomposing temp. Thinner layers give a lot more accuracy when going around corners than thicker layers, and they squeeze the new melt better into the previous layer, so the filling is better. See this test with transparent PET. Each block is 10mm x 10mm x 20mm. The text is a hollow watermark halfway in the blocks. Top row = 50mm/s, bottom row = 10mmm/s. Layer height from left to right: 0.4mm, 0.3mm, 0.2mm, 0.1mm, and 0.06mm. All with the standard 0.4mm nozzle of an UM2. Brown discoloration is degradation due to sitting in the nozzle for a prolonged time at low speeds and layer-heights. But the clarity of the 0.06mm layers at 10mm/s shows that this gives a much better filling, with far less entrapped air. Also, corners are way sharper and cleaner. Bottom photo shows this clearest block as printed, and after cleaning-up and polishing, so the internals become more visible. Text is 3.5mm caps height, text legs are 0.5mm wide. What I sometimes do with a new material, is remove the bowden tube. Manually heat up the nozzle, and insert a piece of the new filament from above. Just like when you would do a cold pull / atomic pull. And then manually adjust temp from low to normal, and manually push some filament through. Then gradually reduce temp again, and feel when the flow stops. Do this a few times. This gives some feeling of when the material starts to flow well.
  19. To me this doesn't look like layer shifts, but rather like a combination of changing of direction of printing (e.g. from clockwise to anti-clockwise), combined with mechanical play in the system? Because the ringing-effect also changed. Maybe try printing a small testmodel where this occurs: print one test quite fast, and next time quite slow? And see if that gives any difference? Printing slower should give better results. But apart from that, I am not familiar enough to give info on how to solve it.
  20. Maybe adjust your nozzle a little bit closer to the build-plate? Or make the first layer thinner, for example 0.2mm instead of 0.3mm? And print the first layer slow enough, so the melt has time to spread well? But it doesn't look too bad to me. Try settings on a small thin testprint, so you don't waste too much time and material. My first layers usually look like below: the grey is for standard PLA prints (first layer = 0.2mm, 20mm/s; all other layers 0.1mm and 50mm/s), the green is for tiny PET prints (first layer 0.1mm, 20mm/s; all other layers 0.06mm, 30mm/s). I have the nozzle closer to the bed than standard, so the first layer is squeezed well into the glass.
  21. I see it this way: letting a model take 2x more time to print, and have it printed correct, costs less time than having to do it 2x or 3x to get it right... So, yes, for a quick draft to estimate things or show a crude concept, a quick print might do. But otherwise I usually do it in good enough quality. Quality and function go above speed for me.
  22. Is this only with this print, or with all prints? What does a small test tower of the same height do? And is it visible in the slicer, in layer-view mode? If printing from SD-card, also try a new card. Maybe in this way you could filter out whether it is a printer issue (hardware, firmware,...), a card issue (corrupt SD-card,...), or a slicer issue (bug, defect in model,...)?
  23. All timing belts I have seen are composites of cord made from hemp or flax (NL: hennep or vlas), or from metal wire, embedded in different sorts of rubber. Much like car and bike tires. The cord is absolutely necessary for strenght, durability and dimensional stability. If the belt is just a drive belt, like in a battle robot, it does not really matter if it fails (apart from that you lose the game). But if it is a valve-timing belt in an internal combustion engine, failure would completely destroy the engine. If you would try to 3D-print that, you are going to have a hard time getting the cord in there. I think you would be better off printing a mould. And then wire the cord in it, in a spiral enless loop. And impregnate that cord with some flexible and very strong composite or PU or liquid rubber? Use plenty of mould releasing agent, and a mould in multiple pieces, or you would never get the thing out of it. If I were in your place, I would try to find a real one, thus search more. In the Netherlands, companies like INDI have a huge amount of mechanical components for machines, including lots of timing belts. If you couldn't find double-sided teethed belts, what about single sided belts, and glueing two together on their backside? There does exist rubber glue for belts and O-rings and seals. Or, depending on the equipment, modify the equipment so it could work with a standard belt of different length? For example by adding or changing a couple of tension wheels or springs?
  24. Does anyone know where to find pure PLA filament? Thus without any additives: no colors, no plasticizers, no strengtheners, no UV-stabilisers or flame-retardants, no similar compounds (e.g. no PLA/PHA blend)... Or does anyone have any past experience with pure PLA, from the early years of 3D-printing? How did it print, concerning speed, nozzle temp, layer height, other settings,...? Was that like modern PLA-variants? I remember from a demo-model that I once saw long ago, that it was very hard and brittle. But if that hardness would be similar to real bone, it might be workable. Pure PLA is biodegradable in the body: it decomposes slowly into lactic acid and CO2, if I understood it well. We might consider trying 3D-printed structures in reconstructive implants. The idea is that the 3D-print gives mechanical support, shape and guidance initially, and is then gradually broken down and replaced by the real natural bone and flesh tissues. Obviously we don't want any colors or other additives with unknown side-effects in there, that could cause poisoning, rejection or allergic reactions. Desinfection is not an issue: we could always do that with strong UV light (this is only required for a short time prior to implanting anyway, not long enough to break down the plastic) and with classic alcohols. And once implanted, the body's immune system should take care of it. But we need to find suitable plastics first... Any ideas?
  25. To make parts waterproof, I print them very slow, cool and in thin layers of 0.06mm. I made a filter for a vacuum pump this way, and tested it by putting water under pressure on it. No leaks. However, when printing in thicker layers of 0.3mm, the water jetted out through lots of tiny openings, where the nozzle had jumped to other layers. When you print with water-soluble support, tiny strands of that support material might end up going through the walls of your model, which after dissolving could leave tiny gaps. Chemically smoothing with dichloromethane should also close tiny gaps and make it waterproof. Or you could paint it. But chemically smoothing can cause cracks later on, because it weakens the chemical structure and might add additional stress. I don't know about internal support structures, as I rarely use them. Another option could be to design custom supports in the model that suit your requirements (strength, removability, waterflow, whatever,...). For example you could design a custom tree-shape support with plenty of openings to wash away support, but still good strength. Probably I would go this route, if I had to design it.
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