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geert_2

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Everything posted by geert_2

  1. Could you rotate the model 90°, so it is laying flat? And then print with 90% or 100% infill? That should give a quite stong part. For casting epoxy into a print, I would rather use no infill at all. Otherwise the infill grid might create weak points where bonding to the epoxy is not very strong, and where air bubbles are entrapped. Another thing to consider might be shrinking of the epoxy, which could deform the model, so try to find a slow-curing, low-shrink and low-exotherm version. But if you plan to use epoxy anyway, what about designing and printing a mould, and then casting the epoxy into it? At least, if the shape of the model allows this (=not too complex, no impossible undercuts)? Then you would have a part in one piece, in one single material. And the mould might be reusable. Also, it might be easier to incorporate fibers or steel wire into it. Only make sure you get *very good* release methods, in multiple layers, so the epoxy does not stick to the mould. Or else, what about printing a single piece of the model, then post-process it and make it nice and smooth, and then cast a silicone mould around it? And then cast the epoxy in the silicone mould? This gives less release problems, due to the non-stickyness and flexibility of the silicone. But still use plenty of release spray, to ease releasing and to prolong mould life. There are lots of good Youtube videos on mould making and casting. Probably this is the method I would try, if I had to do it. This method combines the advantages of 3D-printing with those of silicone moulds and casting. If you have succes, or failure, don't hesitate to show the results here, so that we can learn from it.
  2. Depending on the required accuracy for a good fit (e.g. if it is for tube-couplings for gasses or liquids), I think you might be a bit disappointed with 3D-prints of such tiny models. The layer lines are going to be visible, and accuracy might not be good enough. So you definitely need to get some test samples before buying a printer. Preferably go to someone where you can watch the whole printing process from start to finish. If it is for use in an architectural demo model, thus non functional, and if exact fit is not so much of a consideration, it might be good enough. If you have never 3D-printed before, expect a learning curve, and plan that in. If you need lots of them, all identical, you might also consider low-volume injection moulding in a cheap aluminum mould. For example the sort of things that a company like protolabs can do ("www.protolabs.com"). I am very happy with our 3D-printers, but we mainly print prototypes of ca. 100mm x 50mm x 6mm, and absolute accuracy is not required. 3D-design and 3D-printing is one of the best investments we did in our lab, and I am glad we made that step, even though it took a lot of effort. But we can now make things we could never have done otherwise. But I would not be happy if I had to use it for printing HO-scale model cars (1:87), which are highly detailed and are very small. For such models the prints would not be detailed enough, and the layer lines would destroy the smooth curves of the cars. Have a look at these models: they are printed at 0.1mm layer height and a standard 0.4mm nozzle. With 0.06mm layer height, a 0.25mm nozzle, and more patience, you can get better accuracy, but these effects will still be visible somewhat. It really depends on your requirements. Maybe someone else has a picture of a small model printed with 0.25mm nozzle and 0.06mm layers?
  3. @SteveCox3D: thanks for the write-up. Yes indeed, it would be great if we could get a good list of design considerations for 3D-printing. This will be a great help for new designers. But also after a couple of years of experience, it is good to see things from different viewpoints. We always learn from the experiences of others. Also, a lot depends on the purpose of the models: in my case I don't need ultimate strength. The functionality of the design and ease of printing are more important. So, for me design considerations usually go along this line: - the model has to be functional, thus function determines the shape of the model (contrary to artwork), - orientate it on the build plate so that it requires the least amount of post-processing, - have a good flat underside for good adhesion to the build plate, thus the biggest flattest side is the bottom (no inverted prisms), - the least amount of overhangs requiring support, because supports create ugly undersides and require post processing (I have two UM2 printers, single nozzle), - in case of doubt about strength, oversize the model: I prefer crude "flintstone-like" models above models that fail. Thus some "flintstonisation" is not uncommon, - in case of doubt about fit: provide enough tolerances in the model to ensure a good fit, - avoid big roundings or chamfers at the bottom, since they tend to worsen the tendency for edges of 3D-prints to curl up (thus again: no inverted prisms), - visual quality has to be good, but not perfect: I don't need the smoothness of injection moulded models, I can live with layer lines, - the least possible amount of hollow areas where liquid can seep in (thus I print at 100% filled), - if assembling and glueing is required in post-processing, design alignment features into the model so that fitting parts together is easy, - no threads in the model: if screws are required for assembling, or for clamping parts, then the thread should be provided by a nut; and the nut should be sunken into the model in a hex opening, with some retention, so it does not fall out, - if a models requires supports, design custom supports into the model, and take good care that they can easily be removed afterwards, - edit: if the model needs to be injection moulded for mass production later on, or CNC-machines, incorporate all guidelines for these methods too in the design, I guess these are the most important considerations for me, usually. But the requirements may be very different for other people. People producing art or jewelry will require a much better surface finish than me. For them "no visible layer lines" will have a way higher priority. That is part of the beauty of 3D-printing, that it is so versatile. @sander: I always print in 0.1mm layer height, except for occasional tryouts. The reason is that my typical models have slopes which look ugly when printed in 0.2mm. So I don't have much experience with 0.2mm. When parts in PLA, PET and NGEN break, in my experience the fracture always starts at an inside corner, or an indent between layers, due to stress concentrations, like SteveCox showed in his pictures above. But after that, the fracture goes diagonally straight through everything. It does not follow layer-lines or sausage-lines at all. It breaks more or less like a solid injection moulded model would do. This is for PLA printed with 100% cooling fans, and PET and NGEN printed without cooling fans. I have no experience with other more difficult to print materials like ABS (which appears to separate along layer lines, in the photos on the forum).
  4. Hoi Sander, Have you also tested if, and how, this material does change after a long time, after a year or so? Regular PLA (Ultimaker) and PLA/PHA (colorFabb) do get harder and more brittle after a year. For example snap-fit mechanisms that work well when freshly printed in PLA, get too hard and break after a year if you try to lock/unlock them. The PLA does not crumble, it just gets too stiff to flex. Also these snake clamps (see photo below) get so hard that they are likely to break when I remove them now. While in the beginning they easily snapped around the bowden tube and cables (this is colorFabb PLA/PHA). Also the tube-couplings tend to break when getting older. I believe this effect is due to a change in crystal structure (=getting more crystaline over time), and hydrolysis (=break-down of molecules due to water absorption), but I am not a chemist. How does the new tough PLA behave in this regard?
  5. I can read and speak a little bit of German (Deutsch), but can not write it well enough, so I will do it in English. If the underextrusion is mainly at the left-back corner, where the feeder is, another cause could be that the filament is bent too much to pass through the bowden tube and nozzle smoothly. Filament that is bent too much causes huge friction in the bowden tube and in the nozzle. Also, if the spool is almost empty, it is difficult to unwind filament: it wants to roll up again, like a strong spring. Both effects can cause underextrusion, and sure in combination. On my two UM2 printers (older non-plus versions), before starting a print, I usually unwind 20cm of filament, and then wind it up in the *opposite direction* around a skater wheel of 7cm diameter. This straightens the filament. Then I straighten the next 20cm, the next 20cm,... and so on, until I have done a few meters. This goes fast: it takes only half a minute. Then I wind it all up on the spool again, but now it is sitting very loose. Now it has a bending radius of ca. 30...40cm. This no longer causes problems due to friction. This might be another cause for underextrusion, in addition to the already mentioned ones.
  6. How is bonding different on aluminum, compared to glass? Could you print on bare aluminum, like on glass, for PLA, PET, and similar materials? Does it stick as well, or better, or worse? I am happy with my glass plates, so I have no desire to switch. Just out of curiosity.
  7. I like the shine. Could be useful if you want to visually simulate metals, for example in a technical prototype, but without actually using abrasive metal-filled filaments.
  8. Fluctuations in temperature, in cooling, or in filament diameter? If it were bent rods, I would expect the pattern to run horizontal or vertical, not diagonal. Or a dirty feeder wheel causing uneven feeding? Just guessing...
  9. For colorFabb PLA I can even go down to 180°C if I print very slow on small pieces, 20mm/s, and with a thin layer height of 0.1mm. But usually 190...195°C and 25...30mm/s will do, on my UM2. Could be different for other brands and models. So I second the view of yellowshark: lower the temperature, and print multiple parts together. But in my experience setting a "minimum layer time" does not give optimal results: if the nozzle stays above the model, it keeps radiating too much heat and prevents cooling. If the nozzle is moved away from the model, it tends to leak and cause artefacts. And the molten filament is sitting longer in the nozzle, thus gets more liquid and hotter: this is heat which also needs to dissipate. So, printing multiple models in one shot is better, or print a dummy block next to it. For small models I often print a sort of "inverse" next to the real model. So that layer printing time, and thus layer cooling time, is identical for all layers. This gives best results. Below are a few examples.
  10. Just a thought: instead of maintaining both stable and experimental versions in parallel, what about doing it in *serial*, sort of? For example in this way: develop new features and implement bug fixes during the first 6 months of the year, and release these as *experimental* versions. Then during the last 6 months of the year, only implement bug fixes, but no new features at all. And save all ideas for new features for next year. Of course you would discuss new ideas internally, collect remarks from customers, streamline all these concepts, unofficially do a few internal tryouts on various concepts, etc... But just don't release anything of it. In this way, the last six months of the year would serve as a sort of "reflection time", to thoroughly think things over, and to do some fundamental research. While at the same time making the existing stuff more stable. Also during the last six months, time could be spent on improving the build-in pop-up help, so that each function gets more clear to users. A lot of problems seem to come from users not knowing that some options exist, or not knowing how to optimise them for their particular model. In this way, by the end of each year you would have a really stable version. One that is good enough to last until the next year, for most users. This effectively gives a long term stable release for production work. What would you think about something like this?
  11. Is this material particle-filled? It looks a bit like the shiny "mica" colours in some car paints, which use mica plastic particles. Maybe you can see it, if you look at the models through a microscope, or if you take a high-res photo through a good macro lens? I did a quick google, but I didn't find much about the composition, except that it was "a blend of PLA and other polymers", which doesn't say much...
  12. Thanks for the info. This less or more confirms what I already thought: 100 microns is about 1 layer of 0.1mm, if I am right.
  13. That corner with underextrusion, is that the back left corner where the feeder is? If so, it could be because the filament is bent too much (especially if the spool is almost empty), causing way too much friction in the bowden tube and nozzle. In this case, try rotating the model 90 degrees. Or manually stretch a bit of filament. On my old UM2 - which is sensitive for this problem - I usually unwind 20cm of filament, wind it up in the opposite direction around a skater wheel (7cm diameter), unwind the next 20cm and wind in the opposite direction, etc... until I have done a few meters. Then I wind it up again on the spool, but now it is sitting very loose, with a bending radius of ca. 30...40 cm, about the same as the bowden tube. This reduces friction to almost nothing in the tube and print head. This stretching of filament takes only half a minute. Way less than typing this. :) If it is on all bigger models, it could also be that the little fan behind the nozzle does not work well, causing heat to transfer up into the filament, soften and compressing it, and prevent it from getting into the nozzle. Might be other causes too?
  14. I don't know your printer, so this is just educated guessing. The gaps in the disks look like the top layer is way too thin. I would print such a thin disk between 80% and 100% filled, and with a top layer of at least 1mm. The strings could be non-optimal retraction settings, too hot temperatures, or just the material. Maybe other causes too?
  15. Whatever way you drill (I don't know what is optimal so I leave that to gr5 to answer), I would recommend using a *hand drill*, not an electrical drill. This gives you a much better feeling and control. I bought a separate drill chuck for this. It gives a good grip and allows to apply enough force, but you can still drill very gentle manually. It is also usefull for drilling out holes in 3D-printed models: when using an electrical drill in PLA models, they will melt immediately; but not with this manual drill. For cleaning ashes and debris out of a teflon coupler or nozzle (on my UM2 non-plus printers), and for removing minor deformations, I often use a long brass M3 thread rod with rounded edge. By moving up and down and scratch the walls of the nozzle, this works as a very gentle file. A brass thread is far less agressive than real files, or than steel M3 threads, so it is less likely to do any damage. If the gentle approach does not work well enough, you can still go to more agressive methods.
  16. I also think your bed leveling is good, but bed bonding needs improvement. Which methods did you use for cleaning the glass, and for bonding, if any? Usually I clean the glass with isopropyl alcohol. And then I clean again several times with pure warm tap water; no soaps, no degreaser, no solvents, no other cleaning aids. Soap reduces bonding, and some solvents might leave traces of oils or other stuff if they are cheap commercial grades and not very pure. Then for printing PLA I wipe the glass with a tissue moistened with salt water: gently wipe while it is drying, so it leaves a very thin mist of salt stuck to the glass. This improves bonding for most brands of PLA (but not for other materials). I am not sure why it works for PLA, but it does; probably because salt increases surface tension of the glass? (Contrary to soap and oils which reduce surface tension and reduce bonding. That is how I came upon the idea to search for the inverse: something that increases surface tension, which was salt.) This "salt method" gives good bonding on a heated bed to 60°C for PLA, but after cooling down models come off by themselves without effort; there is no bonding at all on a cold plate.
  17. What about taking "flow rate" during printing into account too? Underextrusion still is a common issue, but it greatly affects strength as it hurts layer bonding and line-width. A good material printed with incorrect flow rate might perform worse than a lesser material with good flow. For example you could take your test bar, and print that as 100% filled at flow rates of 50%, 70%, 80%, 90%, 95%, 100%, 105%, 110%, 120%? This can be done by making one gcode file, and then manually adding the flow rate commands into it. I think this gcode is "M221 Sxxx", where "M221" is the command for flow rate, and "Sxxx" is the desired flow rate in percent, for example: M221 S105 for a 105% flow. I think the Ultimaker testers have done research on this, but I have no idea how systematically it was done? Further, if you want to use parts outside, bio-degradability is an important aspect too. PLA should be bio-degradable, although a PLA sift sitting in my laboratory sink did not seem to degrade in a year time, in wet dirty conditions. Other aspects are UV-resistance and temperature-resistance: PLA will warp in the sun, guaranteed, so you can't use it in a car. Don't ask how I know. :) And most plastics get brittle and crumble after long UV-exposure. You could try this with a strong UV-lamp such as those used for desinfecting aquariums and medical equipment., or for erasing EPROMS. In my experience PLA gets harder and stiffer over time. So snap-fit lockings that worked well originally, will break after a year when activating them, because you keep pushing until the snap-fit mechanism locks in place, or breaks. However, small parts such as key chains and ID-card holders out of PLA survive longer in my pockets than identical parts in PET and NGEN, which break sooner. Just because the PLA is harder. I haven't tried nylon yet. And then there is indeed the mechanical creep over time that gr5 mentioned above. PLA has this, but some light-cured plastics used in some 3D-printing systems have this even far worse, for example the models I had made on a Stratasys Objet v260 jet printer. Most plastics have it to some degree. And then there is paintability, glue-ability (I don't know if that is a good word?), and machinability: these could be required too. All these other aspects might be of great importance too when chosing a material to print, it's not just theoretical strength alone.
  18. @robinmdh: I have no UM3, and in my two UM2-printers the warping creates no real problems. Although I did notice indeed that the edges of the glass plate curl up a little bit in one printer. But I can position my models well enough in the center so that it doesn't hurt bonding to the glass. So I have no real need for accurate tables. It is rather out of scientific curiosity that I would like to know the order of magnitude of deformation: how much does the glass curl up at 60°C, 90°C, 120°C? Is that in the order of 1, 10, or 100 microns? And how much difference there is between different types of glass or other materials? In aluminum it should be less, since aluminum is a very good conductor and all areas should have about the same temp. Glass is a worse conductor. Ceramics (like for CPUs) are good conductors and should have very little thermal expansion. Annealing plastics releases their internal stresses, but it deforms the model. The same is true for metals. So I also wondered what repeated heating/cooling cycles would do with glass? Would they release moulded-in stresses from manufacturing? Or would they rather create additional stresses due to repeated uneven heating cycles, and due to the local very hot nozzle and melt, and the local fans cooling? All of these could contribute to deformations, but I have absolutely no idea which order of magnitude this would be. Although I could imagine that glass plates that are just in-spec originally, would go out of specs due to such effects.
  19. I wonder what the effect is of heating the glass bed (or whatever else bed material) on the warping? Heating creates two temperature gradients in the plate: one from the center (hottest) to the outside (coolest) which is about 10°C in my tests; and one from the bottom to the top. I think both might contribute to warping, and cause the edges to curl up? Further, since glass is a non-crystaline material if I remember well, it slowly deforms over time. Like honey that is sagging, or like asphalt, although thousand times slower. So repeated heating cycles and clamping cycles might also have an effect, as well as storage after production if stored on a non-flat surface or vertically. @mendells: Maybe you could repeat those measurements with both a cold and warm glass, and then after cooling down again, for all the glasses you have? If you could find ceramics like those used for high-grade computer chips and CPUs, dark brown, these might be more stable? I don't know if "ceramic glass" like used for cooking plates are real ceramics (=baked clay), or rather a commercial name for a different type of heat resistant glass (although non-ceramic)? Real ceramics should have a very small thermal expansion and be way stiffer than glass.
  20. If this is the effect you get (see photo), then it is lack of cooling indeed. The ruler shows mm (small lines) and cm (numbers). This is most notably when printing 100% filled models. My solution usually is: print multiple models at a time, or print sort of an "inverse" next to the real model, so the total amount of printing time per layer is always the same, and the time is long enough to provide good cooling. And print cool and slow. Using the option "minimum layer time" alone is not enough in my experience: then the filament sits longer in the nozzle, heats up more, and gets more liquid. This does not really reduce the amount of heat the model needs to dissipate, and the hot nozzle is still sitting on top of a tiny model, is radiating heat, and thus preventing cooling. The nozzle has to move away from the model *and* print something else, so the nozzle-flow is as constant as possible, and the heat source is far away from the part to cool. Effect of not enough cooling time. This should have been nice cones. This picture shows the theoretical concept of printing an inverse dummy next to a tiny real model. This is part of a real design, at the left. At right in pink is the dummy: this dummy only needs to provide extra cooling time while printing the tiny top part of the real model, so it is hollow where no cooling is needed. Putting a desktop fan in front of the printer, at its lowest speed, and at some distance, also helps to gently remove excess heat and improve shape for my models. Depending on your models and materials, lots of similar solutions might be possible. The dummies are waste, but maybe you can design them into some little toys the kids can still use? Like houses for Monopoly, pieces for other board games, or bricks to transport in their toy cars? But in your case the cause could still be something elso too. Such as: too many circle-segments in a too short time for the printer to handle, if the STL-file from which the gcode-file was derived, contained too much detail. Maybe other causes too.
  21. It is hard to see the canals on the photo. But if I had to make such a thing for production runs, I would probably have it machined from solid blocks of nylon, PE, or PP, whatever is most appropriate for your application. This will be much stronger, easier to clean, have a smoother finish, and have a longer life. And then you can use known engineering materials. Sealing of multiple parts could be done by making a seal from solvent-resistant automotive silicone, if you design a canal in the edge where the silicone can go, prior to closing the halves. And design holes for screws and nuts. Most research labs and universities have access to a workshop with CNC machines and qualified operators. Then I would just use 3D-printing to test the concept, prior to having it machined.
  22. Nylon for 3D-printing contains additives too. For example the UM-nylon becomes weak and gets a sort of "snot" feeling when put in water for some time. After drying it hardens again to its normal strong properties. I believe this is due to additives, since this is not standard nylon behaviour. Also, UM-nylon is transparent, while pure nylon usually is milky white. Usually it requires a lot of additives to turn non-transparent plastic into transparent. You also have to keep in mind that 3D-printed models have little holes where the product will creep deeply into the material, and may affect long-term characteristics. (This is also true for bacteria and enzymes: they also get deep into the models, which may make cleaning and desinfecting difficult or impossible.) So I think the only reliable way will be thorough testing indeed. Fill glass jars with your cleaners/desinfectants of choice, and put some complex testprints in it, with lots of little holes. Shake, and let them sit for a couple of weeks. Preferably at a slightly elevated temperature (just below softening temp of the plastic). And regularly inspect for damage. Aceton is guaranteed to damage most plastics or additives. Xylene also (=commonly used in laboratories for parafine removal). But maybe isopropyl alcohol won't do too much damage? This is a standard hospital desinfectant, and a good grease remover. ABS and polystyrene are going to be damaged by most solvents. Pure PLA (without additives) seems to be more resistant to solvents than most other materials, and it is easy to print. At least I don't see any damage when cleaning with isopropyl alcohol and degreasers. Maybe PET and polyesters would also work (e.g.: colorFabb NGEN or similar)? These are all very easy to print without warping, and are reasonably strong and have good layer-bonding. So I would try them first. PE and PP are most resistant, but difficult to print. But I have no idea if PE or PP filament for 3D-printing is pure without additives? Depending on the "cleanness" you need, another option might be to redesign the part so that the majority of the part needs no cleaning at all, like any clamps and the base plate or so. And only a little part that comes into contact with samples needs cleaning or replacement. And then just print a new piece for each test. If this is just a thin plate or thin cup to insert into the rest, it takes very little material and time to print. This might be the cleanest way, if you handle the replacement parts with a tweezer (pincette) to avoid fingerprints. When freshly printed, they are desinfected by the +200°C nozzle temperature anyway. Edit: your post with pictures crossed my one. So my last remark may be no longer valid. I wrote that with small biological samples in mind, like I have seen at my collegues' research.
  23. Today I still have a "template error" in the account settings. Yesterday I also had another one elsewhere (don't exactly remember where), but that seems to be gone? Anyway, these errors seem to have no effect on functionality, as far as I can tell. I also included screendumps of the layout problems in the "print preview" of my browser, and thus also in PDF-prints. Printing to PDF works well with the default theme (blue title bar), but not in the Ultimaker theme: the layout problem of the title running over the text is present in both landscape and portrait format, and in each size (80%; 100%; shrink to fit; etc...). Probably a CSS-problem? This problem of course does have an effect on functionality: reading becomes more difficult. The work-around is simple, but you have to know it: switch to the default theme. Screendumps: Account settings Print preview (and PDF-prints) in Ultimaker theme Print preview in Default theme
  24. I also have that error message "template core ... blablabla... does not exist...", in both themes (default and ultimaker). For example when using "print preview" in my browser (=most recent Pale Moon); and when editing my user profile. But not when just reading messages. In print preview when using the ultimaker-theme, the header is repeated on every page, and it runs *through* the other text. This when "printing to PDF", which is handy to keep usefull postings, for example when diagnosing problems. This might be a problem in the print CSS style sheet? Further, it seems that the system changed my printer to UM3, instead of UM2. I don't know when that happened, I just noticed it today.
  25. Thanks. I hadn't read that post.
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