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Posts posted by geert_2

  1. Whether you use a prime blob or not, I think it is a good idea to use a few lines of skirt anyway.


    This gives an indication if your bed is calibrated at the correct distance, and you have time to manually adjust it if desired (at least on UM2 printers, I don't know about others). You also have an indication if bonding is okay: if the skirt would already fail to stick, the rest will too. And finally, if the nozzle is getting dirty, tiny flakes are often released in the very beginning, showing up in the skirt.


    Also, for my UM2 printers I added a wire to catch the priming blob, so it is not dragged around. It is made from rustfree spring steel, the sort that is used in dental applyances. Very hard to bend in shape, but once bent, it keeps its shape very well, and it stays clamped to the frame. Due to it being a spring, it scrapes the nozzle and then moves down, without hurting it. See the photos from different angles below.








  2. The problem is that systems with sensors and wires on rotating stuff are prone to all sorts of errors: false positives, and not correctly detecting real amounts, due to the spool rotating and the "sensor window" being covered by that rotating spool. These things will complicate the situation.


    But recently there was a post of a guy who printed labels with a measuring scale showing the remaining amount. Then he glued the labels to his spools. The idea was similar to the scales on glass bottles and measuring jars in the kitchen. This actually is a nice and simple solution, I think. It should have been standard on all spools, since it can easily be injection moulded into the spool. But I don't remember that guy's name. Maybe you can find that thread for ideas?


  3. Interesting. And how is layer adhesion? Can you pull layers apart, or is it melted into one solid block?


    PS: I think the word for half-transparent is "translucent": when some light is still shining through, but it's not water-clear. Like the model below (this is colorFabb PLA/PHA, "natural"), which looks like uncooked spaghetti.




  4. This is what I standardly get by printing on bare glass (0.4mm nozzle). The lines are visible, just like they are visible in injection moulded parts where material flows meet, but the indents are very small. The overall appearance is high-gloss (see the lower half of the first photo: here I focused on the fan cover mesh reflected in the bottom).






  5. If you print slow and with thin layers, so that it flows well into all corners, then density is already quite high with the current 90° alternating strategy. For example with 0.4mm nozzle at 0.06mm layers. I don't think density can be improved very much. However, at high speeds and thick layers, there are a lot more voids.


    See the test blocks below of 10mm x 10mm x 20mm. The front one is as printed, the back one is polished to remove some of the outer layer lines and show the inside. The clearness indicates that there are not too much voids inside. This is transparent PET.






    Multiple test blocks together: layer heights from left to right (mm): 0.4; 0.3; 0.2; 0.1; 0.06 (nozzle 0.4mm). Top row printed at 50mm/s; bottom row 10mm/s. So, thin layers and slow speeds give very high density. But you need to print at the lower end of the temp-range, otherwise the material starts to get brown and decompose due to sitting in the nozzle for too long.



  6. 54 minutes ago, NBull said:


    Saying that CO2 is a "life gas. No poison at all" is wrong.

    (CO2) is natural and harmless in small quantities. But if you inhale too much, it "will" kill you. 


    Yes, I can see what you mean. It is a matter of quantities indeed. I'll mention that aspect in further texts.


    Maybe I should have said: "CO2 is a life gass, and no poison at all in normal and slightly elevated quantities". About 0.3% (=10x more than the normal 0.03%) is still almost nothing. In poorly ventilated classrooms the concentration can be much higher than 0.3%, and we are all still alive.


    But in too high quantities it can kill indeed, just like almost anything. Drink 10 liter of water in an hour, and you are dead due to water-poisoning. But water is an essential life-liquid in normal quantities. Breath-in 100% of N2 gas (nitrogen) and you fall dead immediately, in a few seconds, because in the absense of oxygen the nitrogen binds with the hemoglobin irreversibly. I had collegues die in this way 30 years ago. Even though there is 78% of N2 in the air. Same with other essential stuff.


    Further, in the absense of reliable source-info, or in case of conflicting info, as on this subject, I always try to go back to basic and well-proven scientific laws of chemistry, physics, biology, biochemistry, electricity, etc. I try to do the math myself. And I try to look directly at nature as much as possible. Not via-via-via filtered info in the press which may have an unknown agenda. Also, directly looking at applied technologies and machinery is a good way to see if the basic concepts on which they are based do work or not. The fact that a machine works, proves that it is based on at least partially correct principles. This is what I tried to show in the above text.


  7. Randen van overhangende delen hebben de neiging om op te krullen, waarna de nozzle daar met geweld tegenaan kan botsen. Deed zich dat hier ook voor? En dunne paaltjes gaan soms wiebelen.


    Verder: kijk eerst eens in Cura met transparant view en x-ray view of er geen defecten in het model zelf zitten? Indien het okee is, probeer dan eens in een ander materiaal te printen? Gewoon standaard PLA of zo.


    Dit lijkt een "filled material" te zijn, dus met partikeltjes, en die zijn meestal veel brosser dan gewone materialen. Kan je de afgebroken paaltjes manueel makkelijk verder breken?


    Als opkrullende randen een oorzaak zouden zijn, probeer dan een dikkere laaghoogte. Als onvoldoende hechting tussen de lagen een oorzaak zou zijn, probeer dan dunnere lagen bij dezelfde snelheid en temperatuur.


    Of probeer nog meer randdikte, tot die paaltjes volledig gevuld zijn.


    Je snelheid en temperatuur lijken mij okee voor gewoon PLA, dus dat zou het niet mogen zijn.


    Wat je ook kan proberen als het zou blijven breken: de print ofwel even pauzeren, ofwel laten lopen, en dat losse stukje ofwel vastplakken met secondenlijm, ofwel manueel vasthouden tot het terug vastzit langs boven. Of los laten en nadien erin plakken. Afhankelijk van de hoeveelheid nabewerking die je wilt doen (vb. schilderen), kan dat ook nog acceptabel zijn.


    • Like 1

  8. 3 hours ago, jbearpark said:

    I'm more curious as to whether they can be put into regular plastic recycling bins, not sending them back to ultimaker as that definitely would not be worthwhile at a small scale. The printer is a company one and my company has no real way to repurpose them. 

    If you are talking about incineration then you are completely wrong. Plastics do not burn cleanly and release toxic fumes, even with filtering it still produces loading of pollution. 


    I'd like to know your source on this because I have never seen anything pointing to 'plants don't have enough CO2.' CO2 contributes to the greenhouse, trapping radiation in the atmosphere. It also has an adverse affect on humans and animals, displacing oxygen in the air, which is particularly evident in large cities. 


    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.  :-)


  9. 15 hours ago, tinkergnome said:


    @geert_2  - you can modify the shape of the pocket a bit, makes assembling much easier and distributes forces a bit better:




    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?


  10. 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.


  11. 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.




  12. 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.).


  13. 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):



    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:




  14. 4 hours ago, B_Terneyre said:

    Thanks for the tip, but how do I integrate the custom supports/brims in Cura? Should I make a separate file for the support in Solidworks and merge it with my part in Cura? Making the support in the same STL file does not allow me to use separate materials for the part and the support.


    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.


  15. 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?


  16. 3 hours ago, tinkergnome said:


    In case of Fusion 360 you'll never know how long it works offline. It insists to contact the license server every few weeks (AFAIK) and it performs automatic updates that can't be prevented. If the "free of charge" license model (or any other) comes to an end some day... you'll never be able to read your own files again... I don't say this will happen anytime soon, but it's a risk.





    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).


  17. 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.




  18. 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.










  19. 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.


    • Like 1

  20. 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):



    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.


  21. 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?

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