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geert_2

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Everything posted by geert_2

  1. Another factor is cooling: in small models it doesn't get enough cooling time. So the whole thing stays soft and sags. On sharp corners, the strand is pulled inwards like a rubber band. See the tests I did a few months ago. This is PET. Nozzle = 0.4mm. Layer-thickness from left to right (mm): 0.4, 0.3, 0.2, 0.1, 0.06. Top row: 50mm/s, bottom row: 10mm/s. You see the same rounding and not-enough-cooling effects in the thickest layers (left), although less than in your tests.
  2. The screendumps below show why you should not use SketchUp. The vectors do not match up, they do not connect. So you do not get watertight solid models. SketchUp models are a mix of separate surfaces and half-solid parts. Especially if you then do boolean operations on these, it becomes a mess. Below this effect is shown in simple text, before it is extruded into 3D, but the same also happens in other SketchUp models. SketchUp was designed for visual representations only: of buildings, like in games, or for Google's original Earth and Maps views. Not for 3D-printing. If you want to use it for 3D-printing, you manually have to zoom in extremely, and manuall move and close the vectors (see the red arrows where the gaps are that need to be closed). Characters with openings (non-matching vectors) don't fill, don't extrude correctly into 3D, and give problems when printing. Idem for other models. A better solution is to use a program that is designed for modeling solids, for 3D-printing. I use DesignSpark Mechanical. Other people use Onshape, or Fusion360, or (student versions) of Solidworks, and lots of other packages. Search on Youtube for demo videos of 3D-editing programs, and then try one that appeals to you.
  3. Also try using mechanically interlocking features. Since this is highly recommended for injection moulding in overmoulding, according to the manuals, I think it also applies for 3D-printing. At least, it shouldn't hurt. Think of a dovetail system, or hooks, or chains that interlock. Think of these concepts, but then all melted and squeezed into one solid block. Have a look at how it is done in tooth brushes: most of them also have overmoulding with interlocking features.
  4. If you are courageous and have some electronics knowledge, and you want to rule-out the bed-heater influence, you could try to fix a LED-lamp onto the heating-connector. And then babysit the printer to see if the bed-heating LED and print-lines occur at the same moment? (Use a diode + LED + suitable current-limiting resistor, all insulated, not a bare LED alone). But here you risk making short circuits and burning out electronics, so you must know what you are doing. While babysitting a print, also watch if there are any feeding issues: bends in the filament cause increased resistance in the bowden tube and nozzle, or the filament momentarily stuck under other windings, etc. There could also be dirt in the Z-bearings, not only the Z-screw. These are a sort of chain-ball bearings (don't know the correct name), which can get stuck if dirty, or if they are lubricated and the oil gets sticky (some types should not be lubricated, but I am not sure which are used here). Or maybe place a heavy weight on the bed, left and right of the Z-screw, to compress any Z-play, and minimise any irregular friction caused by dirt, compared to this heavy load? And see if it gets worse or better? Not sure if this is a good idea though... Risks overloading the Z-drivers. These things are getting more and more risky, so use them with caution, and only if you have a technical/electronics background. Obviously, I am running out of ideas here... :-)
  5. If it is at *random* heights, or at a fixed height not related to model-features, I would think of a Z-axis issue, such as dirt (thoroughly clean the screw), or play in the nut or driver. But I am not familiar with diagnosing and solving that. If it is always at the exact same height as big changes in print-area, or changes in infill, or changes in wall-thickness, then I would think that there is still something there to improve (thicker walls?), even on bigger models. I have seen models where the infill-pattern shined through the walls, causing indents. A bit similar to the structural ribs shining through the hull of big container ships. Or, if random: maybe a non-constant filament diameter? Or the filament temporary getting stuck, resulting in a lesser flow? Or minor changes in filament color, which show up as darker or lighter lines? I do have a yellow filament that has this: first I thought this was a printer-issue, but upon closer inspection, it was the filament that had those color changes; probably the pigment not mixed well enough. Long ago there also has been a discussion about the bed-heater drawing a lot of current, which could shift the ground-level (zero-voltage) of the electronics, which in turn could shift the perceived temperature from the nozzle temperature sensor, which then could cause the printer to "adjust" nozzle temperature, resulting in a different viscosity of the melt and different nozzle pressure, which might show up in the print. But I have no idea if this could be the case here or not; I don't know the electronics. Could be lots of things, hard to diagnose...
  6. Do you mean that the 8mm rod on which the pulley is mounted, could be shifting (or be shifted) axially, due to too much axial play, or an incorrect plastic spacer? Or one of the pulleys being mounted a bit too far away from the printer-housing? That could also explain the phenomena.
  7. For PET, I get good layer adhesion by printing much slower and cooler, and *without fan*. But then the bridging and overhangs suffer (but most of my models need no bridging and no overhangs). The "printing cooler" is to prevent the filament from burning and decomposing in the nozzle, due to the much longer transit times. I don't know if this would also work for PVC? Anyway, watch out for chlorine gasses, if it would decompose. Should be easy to smell, like in a swimming pool where they overdid it.
  8. I don't have these printers, but on my older UM2, changes in print-area per layer can result in horizontal lines. Especially on smaller models. I think this is due to differences in cooling time per layer, but I am not sure. In your models, are the lines where the solid top and bottom layers begin or end, or where there are big changes in surface area to print? If so, printing with thicker walls, or 100% infill for small models, could help. Also: placing a dummy block next to the real model can help, especially if it is less or more in the inverse shape, or inverse print-area per layer. So that the total printing time per layer is constant. Also, make sure all printing speeds are equal (infill, outer walls,...), so that the material flow is as constant as possible. Another issue could be with the Z-axis (play, dirt,...), but I don't have much experience with that, so I will leave that to others. Printing slow may help too. Layer thickness might or might not help: in some prints I found that very thin layers (0.06mm) gave excellent results, while intermediate layers 0.15mm gave worse results than thinner or thicker layers (e.g. than 0.3mm), on my UM2. Not sure what causes this. See the pics below. The blue/purple model gets severe horizontal lines without the dummy cooling block, at the moment the model transits from big to the small top. The cyan/red model shows the concepts.
  9. I also had this on one belt on one of my UM2: a squeeking sound which turned out to be caused by the belt rubbing against a flange of a pulley. I gently lubricated the edge of that belt with a little bit of silicone grease. But only the edge, and only a *tiny little bit*. Not on the teeth, otherwise it might skip teeth. And I used *silicone* grease: the thick white sort that is also used for microscopes and binoculars. This does not leak away and does not dry out. Don't use petrochemical oils or greases on rubber: this may damage it. This is not an official answer (I am not related to the Ultimaker company), but it solved the problem for me.
  10. Gradual differences: 1) Maybe a different airflow, different air-temperature, different bed-temperature from left to right? If you would have an IR-thermometer gun available, try measuring the bed temp at several spots. I found that in my old UM2, at 100% fan speed, the bed-temp could drop by 10-15°C locally, when printing small objects in PET, so the fans were always blowing hard on a small area. To compensate for this, I did increase bed temp by 10°C for PET. 2) Differences in cleanness? 3) Differences in bonding layer thickness, or method of applying? 4) Differences in nozzle-distance from the bed? But even on the "good" side, I have the impression that bonding is not optimal. I think it would just be a matter of time before they too come off. Are you sure this is PLA, and not ABS or something else? It looks rather dull and weird for PLA (but that could be an optical effect too).
  11. Have you tried measuring if the X- and Y-axis of the printer are perfectly perpendicular? Maybe they are around 89° or 91°, instead of 90.0°?
  12. In the very beginning, on one of my UM2 printers, I had the Z-axis moving down a couple of times during long prints, due to overheating and temporarilty shutting down of the drivers. In mid-print it would fall down 5mm, and then continue printing as if nothing had happened. This was only on long prints, or very intensive use all day. I never had it on the X- or Y-axis, but I can imagine that it is possible too. In my case the solution was to reduce current through the stepper motors. Since then, it never happened again in all those years. If I remember well this was done on the printer, via the settings menu. I don't remember the exact values, maybe from 1200mA to 900mA, or something around this? Maybe try 20% off the current value? If you go too low, the stepper hasn't enough power to move the head anymore, and you get the same problem: skipped steps. Anyway, if you would try this, be sure to write down the original values. Another thing could be lack of lubrication of the rods and bearings. Or wrong oil: I once used "fine oil for sewing machines", but that quickly turned into a thick, sticky gum, almost glue, and it made head movements very hard: I could hear the printer struggling. Now I use hydraulic oil suitable for both industrial equipment (tractors, bulldozers, cranes) and fine test equipment (hydraulic lab testbenches). This oil does not dry out at all, and it collects and removes dust very well. I don't know if this is the best, but I just happened to have 100 liter surplus, so I gave it a try... With the machine off, you should be able to move the head manually without much resistance, and without dead or stuck points halfway. Concerning loose belts or pulleys: I think you should also check the pulleys from the motors, at the back, because they are loaded more. The other pulleys are doubled, so they share the load, but these aren't. Off-topic: how did you generate that mesh-like support structure? And how does the result turn out, in close-up?
  13. Yes, I can see your viewpoint now. To be honest, I hadn't even thought about existing models from others, it simply didn't cross my mind. 🙂 I design mostly for internal laboratory or hospital use, and 95% of the models don't need supports anyway. So I can design towards easy printability, and I wrote the above from that perspective. Also, I am not using the latest Cura version: for my older UM2 machines, the older versions still work fine, so I can't say much about the latest settings.
  14. In short: - a "CAD-program" is for designing *new* 3D-models, or for modifying existing models. Most CAD-programs create vector drawings, sort of, but then in 3D with solid models. CAD-programs are only for modeling, not for printing. - a "slicer" is for cutting an existing model into thin layers and for generating traveling-paths ("toolpaths") for the nozzle, so that this existing model can be printed layer by layer by the printer nozzle. Slicers are *not* for modeling, only for printing. Cura is a slicer, not a CAD-program. - a slicer may allow you to rescale objects, or cut-off a part of an existing model. But you should see that as a printing functionality, not an editing function. So you need 3 things: - first a CAD-program to design a model, - and then a slicer to cut that model into thin layers and toolpaths, - and then a 3D-printer to print it, obviously. In this process you need 3 file-types: - the native vector-fileformat of the CAD-program, so you can edit that model later on. - this model exported to a "surface-fileformat", consisting of small triangles, which can be imported into the slicer (STL, OBJ, 3MF). - a toolpath-file which describes the traject the printer-nozzle has to follow, and which is then loaded into the printer (gcode-file). The CAD-program produces the first two files: the native vectorformat, and the export to STL. The slicer produces the gcode toolpath-file for the printer. And the printer produces the plastic model. There do exist good freeware CAD-programs. I use DesignSpark Mechanical, which is easy to learn. Other people use Fusion360, or other programs. Avoid SketchUp: this will cause endless problems: it was made for visual 3D-models only, not for 3D-printing. DesignSpark Mechanical is for geometric models, based on straight lines, circle-arcs, etc., like machine parts. If you want to design organic models with smooth varying curves, then Blender is a good free program. But it has a very steep learning curve, not optimal for beginners. As said above by others: search in Youtube for demo- and tutorial videos, spend a few days on them, and let that sink-in. And then try something of which the user-interface and workflow appeals to you. What the best program is, depends a lot on your models, requirements, and personal preferences. For DesignSpark Mechanical, these short tutorial videos are good: https://www.youtube.com/playlist?list=PLv91f6GOku1_WEeZMDmspEx0ZC-odebsR
  15. I think you would best use the "shelling" commands in a CAD program. Or delete the top- or bottom surface in CAD, so you end up with a non-solid surface-only model, which has zero wall-thickness and is unprintable at that moment. And then thicken that surface *outwards* until it is 2x nozzle width, so it becomes a printable solid again. And then design some supports, so that the print can stand upwards or upside down, whatever is required for casting, without toppling over. And if required: add pouring canals, venting canals, cut the mould in two halves, make flanges at the seams, provide alignment features, clamping features (e.g. holes for screws or clamps), etc... It all depends on the model, how many undercuts it has, and how flexible the casts are going to be. I would suggest you watch Youtube videos on "mould making and casting". These mostly apply to old-style silicone and gypsum mould making, and casting resins. But a lot of the basic concepts and techniques can also be used in 3D-CAD-designed moulds. I learned a lot from these.
  16. As I just said in another post. I don't have dual nozzle machines, but due to the lots of reports about PVA-problems, if I had dual nozzles, I would custom design and print most of the support in PLA. And only do a small interface in PVA in-between. And I would use a dovetail to let the PVA grip well into the PLA-support. Like this concept. Then you can design the PLA support structure economically but still very stable. Test this concept on a small test piece first, before doing a large model. And stay with the printer to see what happens during the first attempts.
  17. Yes, that could work. But it could also fuse the support into the model, making it very hard to remove the support without extensive cutting and damaging the model. You have to test this first on a small test-model with variations. If I would have dual nozzle machines, I would use PVA-support in this case. However, to minimise PVA consumption and to maximise stability, I might custom design most of the supports to be printed in PLA, and only do a small PVA interface in-between. And I would use a sort of dovetail to make the PVA- and PLA-supports grip well onto each other. I can't try this of course, no dual-nozzle printers, but I believe it should work. The support would of course be a tree-like structure for good stability but economic material use. See this pic for the basic idea. See further down for simple tree-like structures. On my single nozzle UM2 printers, I use various techniques to make support removal easier, also in hard to reach areas, but still keep the bottom of the real model acceptable. However, this bottom inevitably has visible lines and gaps, as you have noticed. Otherwise it would fuse totally with the supports. Ribs do make tighter gaps possible (usually the ribs are 0.5mm wide, separated 1mm from each other). Idem for printing cooler. Also, printing small separate chunks with provisions for inserting hooks, knifes, and tools for pulling hard, makes tighter tolerances possible. This will take trial and error on small test pieces, to see what works for your materials, temperatures, models and speeds.
  18. As gr5 already mentioned: don't use ordinary PLA: it may work a couple of times, but after a while it gets harder and tends to break. Even when printed in the "right direction". And it has too much permanent creep-deformation under continuous load. I use PET now for snap-fit lockings and keychains. It has enough flexibility to survive, and is still easy enough to print. Haven't tried tough-PLA yet, it's on my to-do list. And indeed, do small test pieces first, until you get them right. I would also recommend that you make keychains, carabiner hooks, cloth hangers, and similar stuff that you use every day. And in various materials. Have them sit in your pocket all day, let them lie around in your car in the summer and winter, etc... Then you learn how, why and when they fail, and you can use this knowledge in future designs. Carabiners: the green one is PET (from ICE), the cream ones are PLA/PHA (from colorFabb). They are about 6cm long and 2cm wide, outer dimensions. After a while, the PLA things will deform and crack like this.
  19. Most consumer electronic components are designed for a long-term maximum operating temperature that you can still touch, although barely, about 60°C. This is heat due to power dissipation in an environment of 25°C. Especially electrolytic capacitors, diodes, small transistors, chips, LEDs,... are sensitive. Power transistors and -amplifiers, and resistors, can usually withstand a lot more. Above that temperature the components usually don't die immediately, but their life shortens a lot. And power drivers need to be able to release their heat. I don't know about Ultimaker electronics, but I don't think they use military grade or dedicated high-temp electronics? So I don't think putting the whole printer in a heated cabinet is a good idea. I would suggest: heat the bed and print chamber, but keep all the rest cool: electronics, displays, drivers, power supplies...
  20. Glad you found a solution. I like the idea of printing topographical maps. Where did you find good quality images? Another question: do I understand it correctly that the main purpose of this procedure is to round the 4 corners of the image (but not the mountains themself)? Like a plastic bank card? And to "drill" a hole in it? If so, couldn't the same be achieved in Photoshop by changing the black and white levels of the image, and adding a black or white border around it? (Depending on whether black or white is zero height?) And then import it in Cura and set the base to zero, so that this black border is not printed? Then you could do everything in a graphic editor, and just export a JPG-file. Maybe this might add more flexibility, and you could more easily add logos and stuff? I did a quick concept-test, and with a bit of trial and error this seems to work in an older Cura version, but I don't know in the newest. Edited in Photoshop from a (too) low-resolution image. I set the base thickness to zero, so the black border would not be printed, and the dark grey Rhone-valley is now the lowest part that would be printed. Edit: cutting off 0.1mm from the bottom improves the view in (my version of) Cura.
  21. As far as I understood, slicers don't do boolean math on the STL-files. They rather "count walls", sort of. The first wall it encounters, it switches material on. The second wall = material off. Third wall = material on, fourth wall = off, etc... So any objects totally enclosed by another, will automatically be subtracted and become hollow upon slicing and printing. (But correct me if I am wrong on this.) At least, this is how I make hollow watermarks. In the beginning, I made complex subtract-operations in DesignSpark Mechanical on my CAD models, to get these hollows. But this made subsequent editing difficult, because these hollows are hard to reach. Now I don't: I just move the watermark logo and text inside the main model, without subtracting. So they are "solid blocks inside of other solid blocks". Upon exporting to STL, it makes triangles of those watermark-surfaces. An STL-file just consists of surface-triangles, as far as I understood. No colors, no materials, no solid/hollow-definitions, no dimensions; just triangles... And these triangles are then automatically sliced and printed correctly, using the "wall-count" method. Not sure how it would/should handle models that partially overlap each other, if it should do the exact same, or throw an error? A few examples of watermarks done in this way. Most of the watermark text is 3.5mm high, character-legs are 0.5mm wide, and they are sitting 0.5...1mm below the surface. Obviously, this requires transparent or translucid filament.
  22. The old Cura versions (14.xx) did something like this: it started at the shortest distance away from the current nozzle position, to minimise travel. However, this causes weird infill behaviour in that it starts filling halfway a surface, for example it starts at infill-line nr. 50 and fills-in to line 100, and then jumps back to line 50 and fills up to line nr. 0. This causes weird travel lines in the infill. And in the end it causes more travel instead of less, because of all the required jumps halfway the infill. Instead of nicely filling from line 0 to 100. Maybe you can also reduce problems by setting a high travel speed (to minimise the interruption time), printing slow (=less flow and less pressure buildup in the nozzle), and printing cool (=less leaking, and less heat traveling back up in the filament)? Also, some people slightly oil the filament, to make it slide better through the bowden tube. Some had printed a little-sponge container for oiling and dust-filtering the filament. There have been posts and photos about this subject on this forum, maybe you can find them? If your models would use 100% infill, you could also set wall thickness very high, so it only prints concentric lines, instead of diagonal infill. This causes less traveling at the outside of the model, but it still causes some jumps in the core. Preview the effects of your settings in Layer-View.
  23. Probably not the answer you are looking for, but what about making a human part of the art installation? And let him/her do that? Put him/her on a marble base plate, attach a nice brass label similar to those on stone statues, and shine a spotlight on him/her? That "human piece of art" can handle things like parts stuck to the build plate, or parts falling off prematurely, or cleaning a blocked nozzle. An automaton can't, or not that easy. Further, a human seems way more artfull to me than a silly automaton, and probably way more beautiful too (depending on who you choose, how he/she behaves, and how you clothe him/her). I think humans are masterpieces of art, well, at least some of them.
  24. Maybe you could try cutting out critical parts or features from the design, and assemble them in a small test piece? Then try printing this until you get it optimised.
  25. If this teflon coupler was on my UM2, I would replace it, if I had printing problems. There seems to be an indent inside the tube, close to the bottom, and the inner diameter seems to have gotten oval instead of round? But this is hard to see for sure on photo, as there could be weird light-effects too. Concerning bonding, I think gr5's method with dilluted white wood glue should also work well. At least it did work well when I tried it for PET some years ago. But my "salt method" will *not* work for ABS.
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