geert_2

When saving as STL-file, do you have options for setting the units? If they would be set to mm now (and appear as meters), then you might try setting the units to meters for exporting? Otherwise you could try loading the STL-file in another STL-repair program (I don't know the names), verify it there, and save again? SketchUp is known for creating bad STL-files for 3D-printing. It was designed for creating visual 3D stuff only (houses etc.), no watertight 3D models.

Question: if you tighten the screws "as hard as you can", then don't you destroy them? Or the hex tool? These small M3-things don't look very strong...

I tried the silicone socks with pushing on liquid silicone in a spoon (see pics above), but since that did not work, I dropped the concept. Molten filament kept creeping in-between the nozzle and silicone, due to the pressure applied while extruding (especially when there is a little bit of overextrusion as on the first layers). The silicone was too flexible to prevent this. This molten material then perforated the silicone near the top, so that the melt spilled out at very undesired places. So I removed the silicone again, and now I keep the nozzle clean by wiping it with silicon oil prior to printing, and immediately cleaning it after each print with a paper tissue.

Whatever your scanner choice, I would recommend that you go to a distributor nearby (or someone who has such a scanner, maybe search via 3D-hubs or so). Explain your wishes, and have them scan one of your typical items, and process it in front of your eyes (thus they can play no hidden tricks). So that you can see what the result is, and if it is usable. Pay for it if required. A distributor who has confidence in his equipment and who knows it works for you, will generally be very willing to do this, if it is likely to result in a sale. And he also gains more experience from it, which he can later use for other customers.

I usually design custom supports in my models, as these models are often complex or very small, and the standard supports of Cura don't work well in my case. I design both the models and supports in my CAD program DesignSpark Mechanical (freeware, a limited version of SpaceClaim). Slicing is done in Cura. For ideas on how to make the supports, see this thread: https://ultimaker.com/en/community/34784-best-settings-for-support-structures

If you print on blue tape, the print might stay stuck to the plate. Might, not sure. If you print PLA on bare glass, it will come loose when you stop heating the build plate. If you use my "salt method" (=gently wipe the glass plate with salt water prior to printing PLA) then the print will stick like glue when the plate is hot: 60°C. But there will be absolutely no bonding at all when the plate is at room temp.

As Robert says, try leveling the bed a bit closer to the nozzle. In my experience that helps a lot. Disadvantage is that you get a little bit of "elephant feet". Additionally, to improve bonding, you might also try my "salt method": wipe the build plate with a tissue moistened with salt water prior to printing, so that the glass is covered with a very thin mist of salt, almost invisible. For the full description and photos, see: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ For me this gives a very strong bonding when the glass is hot (60°C), but no bonding at all after cooling down, so no difficulty in removing the models. And it is very easy to apply, no need to take the plate out of the printer. This salt method works very well for Ultimaker and colorFabb PLA, and it still works but not perfect for ICE PLA. So it may work for your PLA too. Let us know. It does not work for ABS (requires some sort of glue instead) and PET (prints better on bare glass).

I hadn't noticed the date either, haha. It appears in addition to being completely banner-blind, I am now getting "date-blind" too. I guess this revival of old threads is a side effect of entering forums via Google. Anyway, it may benefit others. Or even myself in a year or so, after I have long forgotten all my own good design rules...

Instead of my previous reply, now to really answer your question. I think you are facing two problems: 1) First you need to design your thread within the tolerances according to the ISO-standards. On this site, you can find a "metric thread size and tolerance calculator": http://www.amesweb.info/Screws/IsoMetricScrewThread.aspx Here you can select the desired thread (e.g. M4), and the site calculates all tolerances such as min and max diameters, etc. Or Google for: tolerances in metric thread design This subject seems to be quite complex, way too complex for me anyway. And to further complicate things, there appear to be several tolerance classes: loose fit, standard fit, tight fit,... 2) And then you need to 3D-print it, so that it falls within these standards. This is going to be even more difficult, I guess, since accuracy will vary with your printer model and state, nozzle size, printing speed, printing temp, bed temp, cooling, material flow, the type and brand of filament, and whatever else... Also, since the filament is going to "cut corners" when extruded around bends, both inner and outer threads will be too small. (Even a plain 3mm hole often ends up as a 2mm hole in my prints.) So this is going to affect fit also. Maybe this might be the biggest problem. So I think it is going to be "trial and error". But if you change any of the printing parameters afterwards, or you let it print by someone else, it is not going to fit anymore. Small metric threads will probably require rework with thread cutting tools anyway. So if you need standard metric threads, I would recommend using the calculations above and design it accordingly to these standards. Print it and then finish it with a thread cutting tool. Otherwise you have to change your design for every possible printing circumstance. Maybe big and really forgiving custom threads with plenty of play, such as those on big plastic bottles, might work.

Hello Robert, You did not mention the purpose of the thread: does it absolutely have to be a 3D-printed thread? Or must it be a connection that can be disassembled? And would using standard nuts and bolts also be acceptable? I tried designing threads too, but due to the inaccuracies and tolerances in the printing process, I gave up. I had to post-process each thread with thread-cutting tools anyway to remove all blobs, strings, hairs,..., and to make it fit. Thread cutting in PLA is quite difficult due to the low glass transition temp. The threads tended to melt, after which I could not remove my cutting tools anymore, without breaking the part. Even when going very slow, manually, and with good lubrication. Also, the threads proved to be very weak and to wear out very fast. Lightly tightening an M4 in PLA a few times was enough to destroy it. So I switched to standard nylon nuts and bolts instead. In one part I design a hex hole, in which the nut fits perfectly, and is recessed. This hex shape prevents the nut from turning around. Usually I also design-in a sort of retention clip to prevent the nut from falling out when there is no bolt in it. In the other part I design a round hole, in which the bolt head fits, also recessed. And then I only need straight holes with 0.5mm clearance. After printing, I quickly go through the holes with a simple drill, to clean out the blobs and strings. And that's it. This gives a nice connection, with nice recessed standard heads and nuts, but with far less work and problems than designing and 3D-printing custom threads. The nylon screws (or whatever plastic you want) are stronger than the ones you could ever print. And they always fit out of the box. This alternative requires far less design work, makes editing the model faster (requires less CPU and graphics power), requires far less post-processing work, and gives a much stronger connection. I know it's not an answer to your question, but could this be an option for your design too?

@neotko: your observation that it is "not a single line, but doing a line and coming back" on a 0.5mm support is correct indeed. I have also noticed it. But it seems to be not a "full width" line. Probably with a lesser flow, to arrive at an estimated width of 0.5mm? Maybe one of the developers could tell how it is done exactly? I use Cura 14.09, it may be different in other versions. The advantage is that these 0.5mm double lines give a bit more strength than a single 0.4mm line support. And it guarantees that the support will always be printed, even if the STL is slightly inaccurate. So it saves me these worries.

That "recognising problem" is why I make my supports 0.5mm thick, to print with a 0.4mm nozzle. Indeed, if designed exactly 0.4mm, some supports may not be seen by Cura. I am not sure, but my guess is that it may have to do with the STL file: due to the STL-triangles instead of exact shapes of the original model, dimensions may get just a little bit smaller than 0.4mm. And then Cura won't print them (at least not my version 4.09).

Have you tried a different SD-card? Or try formatting the card? Or try loading the STL-file in Cura again, and save it again on the SD-card? I have no idea what the problem is, but from your description and the image it looks like the printer can read part of the gcode-file (which means the printer itself is not dead), but it then gets stuck halfway reading the file. So I would first search in that direction: defectieve SD-card (hardware), corrupt files or FAT-tables on the SD-card (software), bad connections,...

Similar to the image shown by GR5, usually I design all supports manually, and I optimise them for easy removal, good stability, and maximum accuracy of the model to print. In reply to a similar question, I posted a few pics of support concepts that work well for me. See: https://ultimaker.com/en/community/34784-best-settings-for-support-structures

Something I just learned while watching Youtube videos on 3D-printing. So I thought I would just let you know. I haven't seen this mentioned here. When you begin printing with a new filament that you don't know yet, it might be a good idea to remove the bowden tube, and feed a bit of filament trough the feeder manually. Usually you will be doing an atomic pull anyway when switching filaments, so this is a good time. Manually set the nozzle temp to the lower end of the indicated temp range for that filament. And gently (!) push through some filament. See how well it goes. Also manually do a retraction and see how it retracts, and if it leaks. Then adjust the temp in steps of 5°C, and try again. So you get a feel (literally) for what it does at which temperature. This may make it easier to find a good starting point for the settings. Also, you can see whether it needs drying first, prior to printing: if it emits steam, or if it hisses and crackles.

I again tried annealing (post curing) a few items in the UM2 printer. These models are very prone to warping due to their long shape and 100% infill, with high internal forces. They also have sharp corners and indents at the bottom (invisible in these pictures) that makes bonding to the glass plate way more difficult than in models with a flat bottom. Annealing was done directly in the Ultimaker2 printer, immediately after printing, so the printer was used as an oven. Annealing or post-curing these models seemed to increase their temp resistance by about 10°C, and it reduces warping when exposed to heat after the annealing (for example if left in your car in the summer). The test procedure was as follows: The models were printed with standard PLA settings: 210°C nozzle temp, 60°C bed temp, and 50mm/S speed. Glueing to the build plate was insured with my "salt method": gently wiping the glass plate with a tissue moistened with salt water, prior to starting the print. No brim, no raft, no glue, no painter's tape, nothing else. After printing was complete, I immediately set the bed temperature to 60°C manually, so it did not cool down. And then I immediately put a lid on top of the models, to contain the heat. In this case I used a simple frigo box. So that the models are not subjected to air drafts or uneven temperatures. Then I let them sit like this box in the printer during the week-end (2 days). After that I very gradually reduced temperature down from 60°C to 30°C in small steps. For this method to work, the models must glue very well to the build plate, so they do not warp or come off during post-curing. The "salt method" works very well for bonding Ultimaker PLA and colorFabb PLA/PHA, but is not optimal for ICE PLA (here some corners do lift in such difficult models). Disadvantage is that this method occupies the printer for quite some time. In this case I tried two days, but I do not know what the minimum time would be to get good results. This annealing or post-curing should relax internal stresses in the model caused by uneven cooling during printing. It should reorganise crystal structure and give a harder material. At these elevated temperatures around the glass transition temperature, the long molecule chains have a little bit of freedom to reorganise themselves, but not too much. So the heavily stressed molecules will relax, while the less stressed will still keep their shape. At least, that is if I understood things well, but I am not a materials specialist. After this test, the models were put in my laboratory oven and subjected to heat: first 60°C, then 70°C, then 80°C, then 90°C. Untreated models already warped severely at 70°C, bending upwards. The annealed model stayed perfectly flat. At 80°C the annealed model started to warp slightly too, but now downwards, thus in the "wrong" direction. I have no physical explanation for this, but it is like it is. Increasing temp to 90°C did not really make much difference anymore, just a little bit more warping, but not much. When warping, all untreated models shrunk in length, and expanded in height. The annealed model however kept its length, and almost did not expand in height. I do not have hardness measuring tools (and I don't know the standard procedures either), but the annealed models all feel stiffer than untreated models. Photos: First picture: a box used for covering the printed objects while annealing. Second picture: - 1st model (in front): annealed, but no other tests done on it. The thick middle section is 85.5mm long and 6.0mm high. - 2nd model: annealed, then subjected to heat in oven: began to warp at 80°C, in the "wrong" direction. Middle section kept its length. Height increased by 0.02mm, almost nothing. - 3rd model: not annealed, subjected to heat in oven: began to warp at 70°C, in the expected direction: upwards. Shrunk in length by ca 2mm. Height increased by 0.25mm, too much for this application (doesn't fit anymore). - 4th model (at back): not annealed, subjected to heat in oven: began to warp at 60°C, then more severely at 70°C, in the expected direction: up. Shrunk in length by ca. 3mm. Height increased by 0.5mm. - 1st, 2nd and 3rd model: PLA, Ultimaker, color: Pearl - 4th model: PLA, ICE, color: white This is a quick test on a very small number of samples, so it is not scientific, but it gives a rough indication. In summary: annealing or post-curing increases stiffness, and decreases warping and shrinking due to heat. It increases temperature resistance by about 10°C, after which warping and deformation still start to occur, but less than in untreated models (and in the opposite direction, in the case of Ultimaker PLA and colorFabb PLA/PHA; I don't know for other PLA-brands). Thus annealing or post-curing does not do any miracles, but it may be enough for some applications. For example for a non-critical decorative part in your car, or a custom cable clamp in the trunk, or something similar. So I would recommend it for this sort of applications, but not for critical applications (too risky) or for everyday prints (takes too much time). I have no idea what this would do to the PLA's resistance to hydrolysis over a long time span, nor to its biochemical decomposition in nature.

Het kan automatisch in Cura (de precieze knopjes weet ik niet van buiten). Maar dikwijls kan je die supports beter manueel maken in je design programma. Tenminste, als je de modellen zelf kan maken en/of bewerken. De automatiekjes kunnen immers geen rekening houden met de soms zeer specifieke wensen of omstandigheden van modellen. Zie dit topic waar ik zojuist wat uitleg en een paar beelden met suggesties gepost heb: https://ultimaker.com/en/community/34784-best-settings-for-support-structures

Here are a few pics of support-concepts that do work well for my designs. These are just things I learned the hard way; I am in no way a "support design specialist". In all these pics, the ribs on top of the supports are 0.5mm wide, and the horizontal gaps between the ribs are 1.0mm. Usually the vertical gap between ribs and the bottom layer of the model above the support is 0.2mm. Pictures: Bottom left: floating supports: each solid layer and each gap are 0.5mm high. The bottom layer of the supports is sitting on the glass plate, to create a good stable base. The other supports are just floating above it, without connection. This gives a very weak bonding, so the layers can be peeled off. Spacing between the ribs and bottom layer of the model is 0.2mm. Top left, center left: these supports do extend from the model, so I can grip them with pliers and wiggle them loose. Otherwise they are very hard to remove. The width of these supports is only 5.5mm, height is even less. These are too small to get in with a knife. The yellow block is a bit more than 1 cm wide. Top right: side view of a support test model, with different gap heights between supports and model, to try which worked best. The separate blocks make it much easier to remove these supports than if they would have been in one block. Small electronic or dental pliers do fit around the center Y-column of the supports, to pull them out. Center right: in this example one support block is extended, so you can easily grip it with pliers, or with your bare hands, and wiggle it loose. Or you can move a tool into the hole to pull. This is just to show the concept. Bottom right: slanting the support and extending it a bit like this, greatly improves the quality of the first layer of the model above the supports, near the edges. Otherwise that first layer outline sometimes falls off the supports, which these extensions do prevent. In this cyan test block it took a lot more effort to design the supports than it took to make the block itself. These are concepts that a standard automatic support generator obvious would have trouble to do. So for difficult models (small, critical dimensions, hard to access) it may be best to design the supports manually.

Hello again, I have tried smaller gaps than 0.2mm too, but that did not work well with my filament (Ultimaker PLA and colorFabb PLA/PHA) and my models. If the gap is too narrow, the bottom layer of the model sticks too hard to the support. When trying to remove it, this severely damaged the bottom layer of my models. With a gap of 0.2mm or 0.3mm, and the ribs rotated 90° as shown (very important), this gave the best balance between an acceptable bottom layer, and ease of removal of the support. At least for my relatively small models. For bigger models, I might try a bigger gap of 0.4 to 0.5mm. And I would print the model in such a way that the support is located somewhere where surface quality is not too important. The effect of the ribs is double: - They cause the support to not stick too hard to the model, so you can easily remove it. It only sticks on the ribs, not in the gaps in-between. - The ribs prevent sagging of the first layer. - They cause the first layer of the model to be 90° rotated compared to the direction of the ribs. At least in my version of Cura, 14.09. I don't know about earlier or later Cura-versions. This also helps in creating a nicer bottom layer. Of course, the bottom layer is always much uglier than top layers, due to the 0.2mm sagging, but in most cases it is still acceptable, especially for technical models. Not for juwelry of course. I have tried different shapes of ribs, but a rib of 0.5mm wide, with a gap of 0.5 to 1mm seems to work best for me. And it is easy to create on a 0.5mm grid in my editing program (DesignSpark Mechanical), also important. The solid layer in the supports, on which the ribs are modeled, is ment to create a more stable and equal base plate for the ribs. This also improves the quality of the first model layer above the support. The support itself must be very stable. In the image above, I designed the holes in the support at the sides, in which I can insert pliers or tools. In some other models, I did design the holes at the bottom, so I could pull the supports out from the bottom. As you also see in the image, I have cut these supports in four separate parts. Not only because of the different heights in this test, but more important because those separate pieces make it much easier to remove the support. Especially in difficult to access areas. You can easily wiggle each separate part loose. This is not possible if the support is in one big piece. A thing to watch out for, is that you do not get a massive, solid brick of support that you can not wiggle loose, can not access with tools, and can not get out of the holes. Don't ask me how I know. Although in some other occasions, a solid support worked best: for example if I need a deep, small square hole in the model, then a solid support block that extends way out of the hole worked best: so I could easily grab that extension, and wiggle it and pull very hard, without breaking the support itself. It only would break between support and model. Otherwise it would not have been possible to get the support out of the small hole. Sometimes it took me more time to (re)design the supports than the model itself. I would suggest that you design a couple of similar support structures that fit your particular models, and try which gaps and designs work best for you. It depends very much on the model, and on how you are going to remove the support. The support is an integral part of the design. Also forgot to say: if you print cooler, the bonding between support and model will be less strong, and the bottom model layer will sag less onto the support. So this gives a nicer bottom layer of the model too, and makes the support easier to remove. For high quality, a temp of 190°C and slow speed of 20mm/s would usually work better than the defaults for PLA (210°C - 50mm/s) in most cases. In some cases, for very accurate prototyping and complex surfaces, the use of supports was not acceptable at all, or required too much cleaning work. Then the solution was to split the model in several parts that I could all print on a flat side, and then glue these parts together with cyanoacrylate glue. Roughening the surface with a file, and wiping it with an activator before glueing, gives very strong bonds. I haven't had a faillure yet. Or in other prototypes, I just mounted the separate parts together with a few M4 nylon screws and nuts. This is also an option, especially suitable for technical models. Using snap-ins to click parts together is not recommended for PLA: it is too stiff and too brittle. And the layers in Z-direction cause high stresses on the snap-in clips, so they easily break off. If I don't forget, I will try to find a few more images of supports next week.

I have seen brown, grey and black debris, but no green yet. These were all from burnt material inside the nozzle. If you do an atomic pull (also named "cold pull"), is any dirt green too? It could be that some of the white additives decompose, or react with the decomposing PLA and turn green when too hot? What you could try is keep an end of filament in a flame until it melts and starts burning, and see what color that gets?

PLA does get dull and brittle. Out of curiosity, I tried a filter in the waste water syphon of my lab. It took a year or so, and it still functioned, but you could clearly see the dullness and color change (more pale, white-ish). So there is some degradation going on. I haven't tried any other materials, but I would guess that PET or its derivatives are worth a try. They are used for lots of drink bottles anyway. If you select a water-clear filament, you can easier see what is going on inside the material (e.g. color changes).

Just winding it up again might work, while gently guiding the filament by hand. If it is not tangled too much, it might just snap back onto the spool with a little help. At least it does so for my PLA. Otherwise remove the spool from the machine, walk it down your room, hall, garden and street until the filament is all straightened out, and from there wind it up again. Or cut off the unwound piece from the spool and use it up like it is.

If the problem is only on small parts, the cause might be not enough cooling time for each layer, and slight overextrusion due to the print head having to slow down and change direction very often. A solution you could try: print slow and cool (e.g. for PLA: 180°C to 190°C, and 20mm/s). And print a dummy block or tower next to your models. So the printer has to spend some time on that dummy block, and the real models get enough time to cool down. You could also try to set the flow rate to 95%. In my experience this helps for small parts.

What you could also do, is keep the spool of filament locked in a sealed bag with disseccant (if I spell that correctly). And only take it out to unwind and cut off the required amount of filament. Then immediately put the spool sealed away again. And only feed the cut off end into the printer. The disadvantage is that you need to calculate some spare in, and the piece of filament in the bowden tube is always lost. You you have a lot of waste pieces of filament. But this might cost you less than destroyed models, especially in a commercial environment. I am not a fan of wasting material, but in this way the total waste may be less than if you have too many failed models.

In my experience, there are two main causes: 1) For good bed adhesion, the first layer needs to be squished hard agains the glass plate. This tends to spread that layer out a bit, thus widening it. Solution: calibrate the build plate for a higher gap between nozzle and first layer, so that the first layer isn't squished so hard. 2) The heated build plate makes the bottom layers melt and sag a little bit, since the optimal build plate temp is around the glass transition temp of the material (= the temp at which it begins to get weak). Solution: use a lower build plate temp. Both solutions give a far worse adhesion of the model to the build plate. So I usually prefer a little bit of elephant feet, rather than bad adhesion, especially for difficult to print models.