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geert_2

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Everything posted by geert_2

  1. I don't know if it is technically possible. But mechanically, the print head is so bulky that the nozzle can not come close to any object anyway, without hitting it. So I think it would be best to print the models separate, and then "collage" it together with the rest of the collage?
  2. Yes, I know the experience with PLa demo-models left in the car... Now I use PET and NGEN for parts for my car: dash cam filter mount, clamps,... Up till now these have survived unwarped. These materials are still easy to print.
  3. Thanks for the tip. I once tried to grind down a skaterwheel to make it smaller. But after a full day of grinding on an agressive water-cooled disk, I still had gotten only 1mm off. That was when I realised that skater wheels are supposed to be *very* wear resistant... :-) Something else I just think about: any 3D-printed suction cup is likely to be *not* watertight. So it might not work at all. The indents caused by the layer- and printing lines will allow air to seep in and destroy the vacuum. Even in glass lab vacuum equipment, the tiniest scratch will quickly destroy the vacuum. So, even if you make a 3D-printed mould for casting, that mould would require post-processing to remove or fill the indents. Even a very smooth bottom like this won't hold vacuum at all. Unless you have a strong vacuum pump that keeps running all the time.
  4. You should be able to see this in the layer-view in Cura. But you always have the option to design your own custom supports in CAD, and switch off automatically generated supports. Then you have full freedom, and you can design-in features to make removal of the supports easier, or to increase stability, or whatever you want. See the pink and orange supports here, which extend from the model so I can grab them with pliers. This is a very small model, too small to get in with a knife and cut the supports loose. I also provided an additional baseplate to make the support more stable, so it is not knocked over due to its long overhang. Same in red-cyan 3D, which gives better depth-perception:
  5. Multiple models should of course improve cooling, so it can help. But I think the bow wil always be problematic, even with cooling towers. Each time the nozzle lands on or takes off from a surface, this will leave a mark and risks causing a blob, string or hair. This is an area where filament-based printers are not optimal, and liquid resin printers are better, especially those optimised for juwelry. Another thing you want is a very constant flow through the nozzle. So that the melt always has the same temperature and same viscosity. This is why I switch off features like "minimum layer time", which slow down the printer. But then the melt stays too long in the nozzle, gets hotter, and tends to cause more strings and more cooling problems (in my models). Sometimes changing the printing-orientation can also help, e.g. printing it on its back, depending on model geometry and printer (single/dual nozzle). Placing a desktop fan at lowest speed a meter in front of the printer may also help. This gently evacuates built-up hot air, without cooling the nozzle down too much. Playing with retraction settings can also have an influence, but I have never done that, so I can't recommend anything. I just thought about other pictures I had: very small figurines (>2 cm), some printed upside at various speeds and temps, and some printed on their back. The red one was printed slowest and coolest, but I don't remember settings. The hairy one was printed at normal settings (=too hot and fast for these small models) with multiple models at once. The "mummified" one was printed standalone, at normal settings (=too hot). These were all printed with a 0.4mm nozzle, single color, UM2-printer.
  6. Have you considered designing and 3D-printing a mould, and then cast the cup in silicone or polyurethane? Silicone is *very* grippy, temperature resistant, abrasion resistant, but not tear-resistant (tears apart easily). It is water-tight but not oil-tight: oils and solvents seep through slowly. Silicone for casting is usually non-stick (=does not glue to other parts). Be sure to use platinum-cured (=addition-cured) silicone, no tin-cured, because that is not stable and only good for short-term use. PU is usually less grippy but still good, but far stronger than silicone. Think of skater wheels: it is very hard to grind or cut them (don't ask how I know). PU usually bonds very strongly to other parts: so you can cast it around a base and get a good chemical bonding to it.
  7. Also not seeing the pictures here. You can usually drag and drop, or copy and paste, any pictures into your message from Windows Explorer or from any document or website. Maybe the effect you are getting is this? Not enough cooling due to printing on a too small area, so the nozzle stays on top of that one area, keeps radiating heat, and does not allow it to cool down and solidify? Printing slow, cool, and with a dummy tower next to the real model (or multiple real models at once) helps a lot, but does not eliminate the problem.
  8. What about changing the current link name "Join our community" into "Community / Forum"? This would increase the visibility and discoverability of the forum, I think?
  9. This is an interesting thought indeed, but I doubt it is the case here: it happens way too slow over the course of *hours*, not seconds or minutes like bimetals in temperature gauges, or in old flashing lamps and turn signal lamps in cars. And the oven is fully closed, temperature controlled, and heated from all sides. So the samples warm up pretty fast and equal from all directions, initially without warping: this only starts later. So I think the cause is rather to be sought in the direction of slow relaxation of the stresses in the long polymer chains; stresses which were baked-in due to the uneven cooling during printing, line per line and layer per layer. Plus a gradual change in crystal-structure (similar to differences in crystal-structure in metals when they are cooled quickly or slowly, or reheated). That would explain the shrinking in length and the widening. But it still does not really explain the warping in the *inverse* direction after hours for some samples (not all), after they initially warping in the expected upwards way. At least, I don't see it. :-) So I would welcome further ideas on this. Anyway, when heat-treating plastics, people need to take (the risk of) deformations into account, and maybe iterate their design to get the correct dimensions after treatment. Nylon and other plastics can also have different crystal structures, so the same effects could play there I think.
  10. I think with embedded text you will more likely run into issues with strings, blobs and gaps, ruining the aesthetics, than with raised text. Recessed text (pits) is also likely to give issues: the pits getting closed-down, just like small circular holes. The smallest text that I can print and that is legible is 3.5mm high characters (caps height), with legs of 0.5mm wide. This on an UM2 with 0.4mm nozzle, and of course single nozzle and single color. So it has to be recessed or raised text, or hollowed-out (watermark) in transparent materials. This is *not suitable* for aesthetic purposes, it doesn't come close to the beautifull prints of XYZDesignPro, but it is good enough for simple technical labels, such as on the back or bottom of equipment. The reason why I use 0.5mm wide legs instead of 0.4mm (nozzle size), is that in corners the legs often get a little bit narrower than 0.5mm, e.g. 0.48mm (and sometimes a bit wider too, but that doesn't matter). If this was on a 0.40mm leg and it would get 0.38mm, it might not slice correctly and too thin parts might be dropped. Printing slow and cool also helps improving quality. I have a couple of test-plates with recessed, raised and hollowed-out text. Feel free to try them or to use them as inspiration. See here (scroll down a bit to "character set..."): https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ This is what such text looks like:
  11. I am not really a fan of browser-based GUIs, because that leaves you with an additional variable that you are dependent on but have no control over: the browser. Here are a few examples. Firefox was excellent until one day they changed the whole UI and concept, after which it broke all add-ons and became useless for 80% of its users. This broke a lot of people's workflow. Advanced users - like most people here are - tend to install a lot of add-ons in their browser, which may create additional dependencies and trouble. Some people - or some of these add-ons - may disable java, javascript, flash, silverlight, active-x, cookies, external fonts, third-party images, right-click functions, pop-up functions, resize-functions, and whatever else. If you have a good but not very common browser, like Pale Moon (=a Firefox derivation that has kept the old GUI-concept with menubar and statusbar), then this is often not recognised by the server. And then the server messes-up its webpages by *assuming* stupid things, for example that I have a micro-screen of 320x240 pixels instead of my real 1920x1080 pixels. So it sends me garbage instead of standard HTML: it sends fonts of 5cm high, so only a few lines fit on my huge screen. The bigger the organisation, and the more they are specialised in communication (e.g. news-sites and newspapers), the worse this gets, and the less they communicate. A lot of modern browsers even mess-up perfectly valid and simple standard HTML, which by design should reflow automatically in the available window. The browser should take the default font-settings if not specified, without changing them. But they don't. For example Google Chrome Mobile rescales some paragraph's font-sizes (sometimes making it larger, sometimes smaller), but not other paragraphs. And some browsers refuse to reflow text, so it falls off the screen. So you can't even limit yourself to old-school 1995's HTML and forms, because even these break today. You don't want that kind of trouble in a slicer GUI. Cloud-based computing is even worse: then you become dependent on a very unstable variable: the internet/network, coming with all its interruptions and its hazards (virusses, spyware, interception, industrial espionage...). It is unusable while moving (train, plane) or in remote areas: even Germany has no internet in lots of its eastern rural areas. And the data going over their monthly limit, and you going over your budget. Also, this creates GDPR and similar legal problems. So I prefer independent standalone applications installed on and running on the local computer. One application per function. Preferably with all user-settings stored in the same directory as the main program, or a subdirectory "user-settings". Not splattered all over the harddisk in unaccessible directories. So that it is portable. Although of course all programs should use generic and standard datafiles for smooth data-exchange. I am aware that my view may not be "politically correct", but this has proven to work best (for me).
  12. I guess it must be something somewhere in your design that has such a big shape? Maybe a part way out of view on top? Or incorrect printer head-size settings, or an incorrect printer, so it thinks it has a very large print head? So it will stay clear of the edges, to not bang the head into the wall? Something along this line of thinking?
  13. My guess is one of the following: - overextrusion, - blue tape coming off the bed, with air being entrapped below it, - the filament not sticking to the tape for whatever reason. If you watch closely while it is printing, maybe you can see what happens.
  14. I once got wounded by a tiny 50mm computerfan running at overspeed, so the blades were ripped off and flew all across the room. And that was a standard injection moulded glassfiber reinforced nylon fan... (It was running *way* overspeed...) So, 3D-printing any propeller- or turbine-like blades looks like a risky business to me. Airplane propellers and turbines are carefully X-rayed for cracks and voids. FDM 3D-prints are by concept full of such "cracks" due to the way the molten "sausages" are laid down. Also, the surface of the blades needs to be very smooth to get a good airflow, and the airfoil shape needs to be very accurate, both which you won't get with a 3D-print. I think you would be better off making a mould from a real model (thus a duplicate), or if it is a new design, from a carefully post-processed and smoothed 3D-print, and then cast it in strong PU or whatever composite you want. If you cast in a transparent material, you can see any bubbles. If you select a slow-curing resin, you can evacuate the bubbles by vacuum and shaking or tapping. If the mould is big enough, you can also add high-strength fiberglass or other fiber reinforcements, around which you cast. Just like in real airplanes or good safety helmets. Plastic injection-moulded safety helmets are worthless crap, but the good helmets made from composite-resin impregnated fibers can be hit by a heavy hammer several times without fracturing. They don't come apart, which is what you might want.
  15. Actually I have no idea of the percent: I take an old glass bottle, fill it half with water, and just pour in quite a bit of salt. Enough to make it taste really salt, but not so much that it does not dissolve anymore. It is not critical. And if kept in the fridge, it stays good for months. Concerning the rest of the settings: this is hard to say, since it is influenced by materials, model, circumstances and personal preferences. For me the standard settings work pretty well: 0.1mm layers, 60°C bed, 200...210°C nozzle, 50mm/s. For very small objects that need better quality, I print slower and cooler than standard: 190°C, 25mm/s. I rarely print large objects, but if so, I often use 0.2 or 0.3mm layer height, 50mm/s, 210...220°C. Also, overhangs come out better with thicker layers. Just try what works best for you.
  16. If it is just a cap, why not leave out all internal extension and pin holes? So you only have the outside? But I think you would best print this in a softer material. An alternative might be to print a small cup, sacrifice a real connector and clamp it in that cup, and then pour silicone moulds (non-stick model-making silicone) of this? Then the silicone plug will have the correct dimensions, and it is flexible.
  17. The first layer may be too cold. Hotter gives better bonding. Also, it needs to be squished well into the glass, thus into very thin flat layers, not round sausages. You did not mention if you used any bonding agent, so I guess not? Some people have excellent results with 10% dilluted wood glue in water (user gr5's method), some with the standard stick (sometimes with spreading the glue with a wet tissue), some with hairspray (user neotko). I prefer my "salt method": after cleaning the glass, then clean again with pure warm tap water only. And then wipe it with a tissue moistened with salt water. Gently keep wiping while it dries. This leaves a thin mist of an almost invisible layer of salt stuck to the glass. It greatly improves bonding when the glass is hot (compared to printing on bare glass), especially in moist weather when bonding is low otherwise. After cooling down, the models pop off by themself. For the next print, just wipe the glass again with the salt water. No need to take it out anymore. For me the ease of application and the ease of taking the models out, makes this attractive. It works very well for PLA, and for my low and wide models. But I do not recommend it for narrow and high models like statues or lantern poles: these tend to get knocked over. For these, use a glue that can absorb shocks better. Also, it does not work for ABS, PET (it makes PET a bit less sticky). For my old but still usable manual, see: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ The model at the front is freshly printed. The one at the back was heated in an oven at elevated temperature (70...80°C), to see how it would warp and shrink, which it did obviously, thereby showing the huge internal stresses. It prints fine without lifting corners at 100% infill. Below is a small test model I use to try which bonding methods work well. It excerts huge warping forces due to the large overhangs and small bottom area, so good for testing and comparing. Stay with the printer, as this is likely to come off and produce "spaghetti". Dimensions of my model above, to give an idea.
  18. Recently I tried glueing PP-straps back together after cutting them. It were injection moulded parts, not printed. You can bond them with cyanoacrylate, after roughening up the surface by sanding, and after using an "activator". These activators come in little tubes similar to a fluo pen marker with felt tip, except that the liquid is not ink but a chemical that partially dissolves the plastic (at least I think so, but I am not sure how it works chemically). Then apply the cyanoacrylate and *immediately* press parts together. The activator makes the bonding stronger and also speeds up curing, so you only have a few seconds before it is too hard. I found these in a normal super market (such as Delhaize, Carrefour) and hardware shops (such as Brico, Hubo, and similar here in Belgium). Bonding strength is comparable with older glues like contact glues and "universal glues". But it is *far less* than what we got used to today with cyanoacrylates and composite glues on good substrates. So under high loads and especially when peeling, it may fail. Depending on your application - if purely decorative, light loads or big surfaces - it can work. Under high loads, I think you would be better off screwing, clamping (e.g. snap-fits or dovetails), or welding parts together. An activator also improves bonding strength of PLA with cyanoacrylate, but the working time is reduced so much that it gets quite uncomfortable. You don't have time to align parts correctly anymore, they stick immediately. And if you are too slow, the glue is hard before even touching.
  19. What I was thinking about, is to design and print a small item like this (the square baseplate is 50mm x 50mm). The 45° overhanging edges are likely to curl up (at least with PLA, at 100% infill, and on my printers), and cause the nozzle to bump into them violently, creating a hard test. Then dial up printing speed until it starts causing trouble and skipping steps. And then dial down until these go away. That will give you an idea of how fast you can maximally go. And then reduce further for a safety margin. Maybe that could work as a test?
  20. If your printer has a front panel, then maybe you could change the speed while it is printing, without having to go into the gcode? Like we can do on our Ultimakers? But I don't know your printer, so I don't know if it has this functionality?
  21. I don't know the cause of the slicing problem, so I will leave that to others. But even if you could get it to slice correctly, the 6 tiny holes will be way too small to print, I think: they will get closed down. Also the circular gap around the holes will become too narrow to be functional, if it has to be functional and not only visual. (It looks like a cap for a DIN-connector or something similar?) Unless you would use a 0.25mm nozzle at low speed, temp and layer heights, then you might have a chance.
  22. Have you tried designing a custom brim in the CAD file itself, and maybe some sort of tree-like or inverse-tree supports? Just to add more stability? I guess it now starts wobbling around due to the brim or supports not being stiff enough? An added issue could be not enough cooling, due to the hot nozzle sitting continuously on a small area, which tends to increase this sort of effects. So, adding a dummy cooling tower or printing multiple at once might improve this. But it might also worsen the situation if during traveling around, the nozzle would hit the legs...
  23. If you are printing near your printers maximum, then the slightest bump can cause skipping steps. Overhangs often tend to curl up, so that can be enough to trigger it. At slow speeds the force required to accelerate and move is far less, so the printer has more margin before it skips steps. Maybe try a small test print with overhangs and other difficult stuff, and on the fly change settings up to the point where it starts skipping (or underextruding or whatever else problem comes first)?
  24. That is very severe underextrusion, which can have a ton of causes: partially blocked nozzle, worn-out teflon coupler, bad little nozzle fan, dirty feeder, too wide filament, friction in feeding traject, printing too cold, too fast, etc... Search for the whole list made by user gr5 on this forum (I don't know it by head), which has excellent info.
  25. Yes, I have seen it, good. Reachability is key. :-)
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