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geert_2

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Everything posted by geert_2

  1. 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 is the main food for plants. It is a life gas. No poison at all. All greenhouses inject huge amounts of CO2 into their glass greenhouses, to increase their crop growth. Where I live in Belgium, we have a lot of them, and they all have *huge* CO2-tanks next to their green houses. This costs them huge amounts of money. They wouldn't do it if it had no benefit. The most economical balance for them here in Europe is a CO2-amount of 0.1% to 0.15% in the air, thus ca. 3x more than in open air. Below that, crop growth isn't enough, above that is becomes too costly for a small added benefits in growth. In formula: CO2 + H2O + lots of sunlight as energy ---> C-H-O chains + O2 In which the C-H-O chains are juices (sugar), green leaf, and wood, with C6H12O6 being one of the simplest forms of sugar. When injecting more CO2, the limiting factor here in Europe becomes lack of sunlight to produce the energy required to convert the CO2 and water into wood. Wood is essentially "stored sunlight energy". That is why it gives so much heat when burning it. In other words: plants convert sunlight, CO2 and water into wood. Wood is stored sun-energy. This is why it is much cooler in a forest than on bare rock in summer: the plants have already "eaten up" all sunlight energy before it reaches the earth. So it can no longer heat the climate. It is converted into wood. More CO2 = more green and more wood = lower temperature in summer. So, CO2 has a cooling effect on the atmosphere, instead of warming effect. You can easily see and feel this for yourself in every forest. This is basic science: look at reality and describe what you see. You have to take the whole effect into account, with all feedback mechanisms and stabilising mechanisms. Out of experiments, people found that the rule of thumb is: 10x more CO2 (which is still only 0.3%, thus almost nothing), gives 6x to 7x more green, without you having to do anything. All deserts would become green automatically and be covered in forest again. There is enough moisture in the air, but not enough CO2. If there would be more CO2, plants wouldn't need to open their pores so much, and they wouldn't lose so much water vapour. Then the current amount of moisture in the air is enough, even in the deserts of Africa. This has been tested. We, humans and animals, do the opposite of plants: we eat green plants, we breath in O2, and we decompose them into CO2 and H2O, releasing the stored sun-energy to keep our body warm and to move. In formula: C-H-O-chains (food) + O2 ---> CO2 + H2O + energy Yes, if you put CO2 in a laboratory tube, and you put that tube in the sun, it warms up more than an empty tube. But that is no science: it does not take all the feedback mechanisms into account; it throws out 99% of effects. When researching this subject, I also found that drug producers use CO2-enrichtment to grow their plants. They too recommend a 0.1% to 0.15% of CO2 (compared to the current 0.03% ... 0.04% in the open air). They wouldn't do it if it wouldn't work. So, even drug producers are more aware of science than politicians; very remarcable. On Youtube you also find videos of plant growth by various CO2 levels: below 0.02% plants don't grow well: they stay sick. At current levels, they grow poorly. At CO2-enriched levels they grow much faster, stronger, and healthier. There do exist a couple of good documentaries (try different search engines, because Google is more and more censoring this sort of content): - The greening of planet earth - The greening of planet earth (continued) - The great global warming swindle and tens of others Also search for: - real co2 science - co2 swindle - co2 warming hoax and similar About coal, brown coal ("bruinkool" in Dutch), and similar decomposed organic stuff (in Dutch: turf, veen). These materials were plants too, long ago. But all that carbon got entrapped into the soil, so it can no longer be part of the life cycle. Once the whole earth was covered in green forest. But these leafs felt down and got buried in the ground, entrapping all that valuable carbon. So the earth became a desert to a large degree. Probably this is also true for some of the oil and gas in the earth: this too seems to have come (in part) from decomposed organic life forms (including sea life organisms). But maybe not all: maybe some oil and gas were always there, like metals and other chemicals were always there. So we should dig up all this trapped carbon, coal, oil and gas, and we should burn it in a clean way, with filters and catalysators, to release CO2. So the carbon can be part of the life-cycle again, and the whole earth can become green again. If CO2-levels rise by 10x, and plants grow quicker by 6x...7x, then all people would have enough food automatically. And all animals would have a huge habitat. So, to save the plants and forests, and to save life on earth, we should dig up as much oil, gas and coal as possible, and burn that in a clean way. So we should go driving old-style cars with fuel guzzling V8-engines of 400HP again, but now with filters and catalysators. This is no joke, it is solid science. :-) And by the way, even if earth's temperature would rise 2°C, sea levels wouldn't rise, no: they would drop instead. Currently the ocean temperature is +2°C (except the top 200m). But water has its highest density and lowest volume at +4°C. So, if temperature increases with 2°C, ocean levels would drop because the water shrinks. Combine that with all deserts getting green again, which will store huge amounts of water on land, and sea levels will even drop further. Ice on the North-pole is floating ice on water: if that melts, it has no effect at all on sea levels. And it is only 2m thick anyway currently in summer: you can already sail to the North-pole by ship since 20 years. Search on Youtube for: ice breaker north pole cruise. The ice on land on the South-pole won't melt: it is way too cold there: even if temp rises with 20°C, it is still minus 40°C. Same for Greenland, in a lesser degree. And polar bears are doing fine: their population is increasing very well. Polar bears need thin ice and water, not thick ice, to live: they need to fish in the water. If the North-pole would get covered in thick solid ice, they would have no food and die. I am very much concerned about the earth, plants, forests, and life. But I am also very much concerned about scientific facts and thruth. I am aware that this is a bit off-topic for 3D-printing, but we are technicians and developers. We are among the very few people who are capable of looking at reality. Otherwise we would not be able to develop working equipment. And we have some knowledge of science and technology. Most other people don't. Politicians, fanatics, and press-people are even not allowed to look at the facts, or they are thrown out of their group and lose their job. So we should stick to scientific facts, and we should not go along in current CO2-hysteria, lies, and child-crusades. I would really encourage you to have a closer look at this subject. It will open a new world. It is a much longer reply than I had planned, but fortunately I can type quite fast. :-)
  2. 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 poster can also use this concept for a better fit?
  3. 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 collection system (provided that you have one in your area), might be the most environmentally friendly. On the condition that it is burned cleanly, and its heat is re-used to produce electricity or warming for other purposes, and with good exhaust filters. Apart from that: CO2 is not a poison gas, on the contrary: it is the most important life-gas on earth: it is food for plants, and it is the base of all life. No CO2 means no life. Today there is not enough CO2 in the atmosphere to make plants grow well: they need at least 3x more CO2, but preferably 10x more (that would still be only between 0.1 and 0.4%). This has been tested in scientific experiments. Today concentration is 0.03% and plants are in continuous "CO2-hunger": below 0.02% they all die. So, don't feel bad for producing CO2 and making plants grow. This is basic scientific knowledge, which I got in highschool (around age 15...18y). But of course the climate-kiddies today don't go to school, and they are too lazy (and too arrogant) to study and to inform themself. And the press is just a propaganda-channel of its owners, not a thruth-channel, so you won't read this in there. Also see my text, via the link a few posts above this one, for more info.
  4. 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 worked best, and I used that for the real design. Steel nuts are hard to force into too small holes in a PLA model, but for nylon nuts it is easier.
  5. 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 design custom supports for all my models that require support, and I design-in features to make the support stable enough and make removal easier in hard to reach areas (e.g.: extensions to grip the support with pliers, or holes to insert pulling-hooks, etc.).
  6. 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 a bit): https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ This works very well for my long and flat models. But it is not recommended for narrow, high models like lantern poles: they tend to get knocked over. Further, I still think your bed could be a bit closer to the nozzle. See the photos below how the bottoms of my prints look. For my UM2 printers, I made a tool to catch the priming blob, so it is not dragged into the print. It is in spring steel wire (like used in dentistry). The idea originally came from another user, but I don't remember the name. See the photos. Clamp to catch priming blob: Glossy bottom of prints, reflect light well (see plate with "design"): Bottom of a print: top part is focused on the model, below is focused on the reflection of a fan cover in that bottom (I couldn't get both in-focus at the same time): Inverted prism, printed with my "salt method": edges tend to warp due to strong forces of huge overhangs, but the model could be completed without coming off the bed. This is the edge of what is possible with the salt method. Flat bottom, almost no lines: Salt method:
  7. 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 soon as you start using dissolvable supports, you risk strings of that support material running through your solid parts, spoiling the watertightness.
  8. 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 hindering the flow, worn-out teflon coupler (UM2), or less likely and if the lines are in pairs: too much play in the rubber belts? What if you do a small test cube at low speed, at 100% infill?
  9. 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 people in California. Maybe you have an offline emergency generator, but there won't be any internet-transmissions if the relay-points have no power. Or if there is a virus attack on the servers, making them unavailable. Or if you live outside of the US, in case of an embargo. Plenty of reasons why the internet-connection mail fail. If you use an online service, be sure to export your models into a generic format too, such as STEP or IGES (I think), or any other file format that your program can handle well, and that other software can import. Also store the STL and/or OBJ files of it, so you can at least print existing models. Store all those copies offline at your own location on multiple harddisks, kept in different places (in case of fire or theft).
  10. 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 their ground contact area would be too small, and the nozzle banging into the overhangs would knock off these parts. Edges of overhangs tend to curl up, so they get a rough treatment from the fast moving nozzle slamming into these edges. This is a small model: the watermark text is 3.5mm caps height, and its legs are 0.5mm wide.
  11. 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 if they would, I am sure they would be watertight.
  12. 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.
  13. 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.
  14. 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
  15. 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 you like.
  16. Maybe there is some debris stuck between the plastic housing parts of the head? Because they obviously do not fit together: there is a huge gap in the last photo. I would suggest you search the manual on how to disassemble the head and nozzle on the UM-site, and on Google. I think there are also tutorial vids on Youtube. So you have multiple viewpoints. And then remove and carefully inspect the black plastic parts?
  17. Another option might be to make a mould, and cast it with a high-temp material, glass- or fiber-filled, or non-filled, whatever you desire? There do exist high-temp polyurethane and composite materials. You could 3D-print the original model, clean it up until perfect, and then make a silicone mould of it? There are lots of good video-tutorials on Youtube. Search for: moulding and casting Also, depending on the vibrations and load-spikes, I am not sure a snap-fit mechanism would hold. It surely wouldn't if mounted on a diesel engine block at a rough coldstart. In such a case you might want to provide additional clamps: metal spring clamps, multiple nylon cable binders (but they tend to fail under heavy load), self-locking screws, or similar common automotive clamps? If you could avoid the snap-fit, you have no problems with flexibility requirements for it.
  18. Yes, this seems like a very good idea, I hadn't thought of that: less friction, and far less complexity, especially when changing filament. You just need to make sure that the external tubing is long and flexible enough to be pulled up to the feeder automatically when the filament moves.
  19. I think you can clamp the bowden tube with pneumatic clamps/fittings. I guess the bowden tube is a standard size, but maybe imperial? Your tubing might have a different outer diameter. And then you would need to design some sort of housing for that clamp, and mount that housing next to the feeder. See the pneumatic fittings in the image below (the ones with a thread).
  20. Watermarks do reduce strength of the model, obviously, since there is no material there, and the gaps might concentrate stresses. Apart from that, I never had issues with internal watermarks. Except if the hollows are too big, and their "roof" doesn't close very well: then you see some spaghetti or grape-like blobs sagging inside. And if they are too deep into the model, they become invisible or blurred, due to the layer lines acting as a blur filter. But this is just cosmetic. In my keychains above, it hasn't caused any mechanical or software-trouble. Originally I made watermarks by subtracting the watermark text from the main model. But this proved unnecessary. It is sufficient to just move the text inside the model, without any further operations. Then, upon export to STL it is automatically subtracted correctly, since STL are just triangles without any meaning. As far as I understood, "watertight" has nothing to do with hollow design features like watermarks, but with the edges of the model touching each other correctly. If you fold a paper model incorrectly, it has gaps in the seams, so it is not watertight. The same in STL: edges of triangles not touching each other. I made these keychains in DesignSpark Mechanical, and exported to STL. Don't use SketchUp: this causes problems with watertightness indeed: its vectors don't match, and they don't close gaps in the seams. Concerning the reinforcement of holes, I think this is possible by defining a different infill percentage around the holes. But I don't know the details, so I will leave that to others.
  21. My experience is that usually I have to drill out holes anyway, because of occasional little blobs, strings and hairs. I also tend to make them 0.5mm wider in CAD than necessary: thus 4.5mm for a 4mm hole to slide an M4 bolt through. And then I *manually* drill it out (see photo). This only takes a few seconds. No electric drilling, especially not in PLA, because it melts immediately.
  22. I have seen this problem too in long prints: while printing, the model sticks to the glass very well: no lifting/warping at all. But after removal, it starts to deform slightly. And indeed, for PLA usually the center "lifts" half a mm, if you put it on a flat table. So this must be due to residual cooling stresses in the material, which are not enough to pull the part off the glass, but enough to slightly bend it. However, I don't have a good solution: warming it up again to release the stresses, tends to make things worse, far worse. I have had models warp upwards on the edges. Or others warping upwards at first, but then after some time reverting and severely warping in the other direction, very weird. And they shrink in length, but expand in width and height with several percent. Maybe, if you could clamp the model between heavy metal plates, and gently warm it up to around its glass transition temp, and very slowly cool down, you could remove some of these stresses? Or let it sit for a night on the warm glass bed of the printer, before removing it (and cover the bed with a box, so temp is uniform)? Edit: the photo shows some of the warped test models. In this case they were subjected to way more elevated temperatures after printing, to try the effects of annealing. Thus way above glass transition temp. But the bending upwards in the center shown in the second model, is also very lightly present in 20cm long models, immediately after removing from the glass (although far less than shown here, only ca. 0.5mm).
  23. With an ohm-meter, try measuring if the nozzle is grounded indeed. (Edit: do this only when the printer is switched off, and disconnected from the mains supply, of course!) But glass itself is easily charged, so there is always a possibility that heat and airflow do charge the glass and the lower part of the print, even if the nozzle would be grounded. Or by pulling the print off the glass. This is guessing, but I think the main charge on models will come from post-processing: grinding, cutting off defects,... And it will depend a lot on the material. Do dust and small particles stick to your prints? Then they are charged. There do exist anti-static sprays: in the old days we used them on CRT displays. The glass of those big color monitors tended to get so charged up that you could pull sparks of several centimeters, causing sore arms, and burn-pits in the display, due to their 30000 Volt transformers. Maybe you can still find those sprays?
  24. Yes, exactly the same as I use; found it in a car accessory shop. :-) If you want to remove moisture from already bad filament, I think it is best to use both: a big bag of silica gel, in a hot environment (a sealed box on a heated printer bed, or in a computer-controlled oven). The elevated temperature might be necessary to dislodge the moisture from the filament. But be sure to stay below the glass transition temp of the filament, so it does not deform or melt. And then, once dry, store it in a closed box or bag with the silica gel.
  25. The purpose is to reduce inertia. Each gram less improves print quality, because you get less vibration, less "ringing" around corners, less overextrusion at corners (the nozzle can accelerate and decelerate faster), and you can print faster. A drive motor weights a lot, compared to the rest of the head. If the head is lighter, the gantry can also be made lighter, which further improves print quality.
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