geert_2

Is the printer still cooling down from before, or is it just always? It may take quite a long time to cool down, depending on the situation, the airflow, and the bed-temp of the previous print. Or could it be heat transfered from the electronics below, or a nearby heater, or sunlight? Behind a window in the sun, it can easily be 60°C, like in a car. I would say: in the morning, after being off for the night, measure the temp before switching it on. Then, without printing, measure again after half an hour or an hour. It should still be about room temp, maybe a little bit more. Shut off windows or other heat sources. I think that could give you an idea if the electronics are fried (short circuit or so).

The cooling fan blows cold air onto the model and glass. In my tests this could give a local difference of up to 15°C on the glass plate for small models. This could be a major source of difference, as the sensor is at the bottom of the glass, not the top.

I don't know your filament, but I have also seen this in other brands: especially high-filled colors - thus with lots of pigments, or special pigments - print differently from uncolored filament. For example I have seen this in white, yellow, light-green, black,...

De standaardsettings zijn een goed gemiddelde. Maar voor zeer kleine voorwerpen, of als hoge nauwkeurigheid vereist is en je wilt in dunne lagen printen, kan je beter koeler en trager gaan. En omgekeerd: als je zeer snel wil printen in dikke lagen, kan je beter wat warmer gaan. Het is goed om dat in testprints eens uit te proberen, gewoon om inzicht en ervaring te krijgen in wat het precies doet. Maar als de standaard prima voldoet voor jouw modellen, is er inderdaad geen reden om ervan af te wijken. Over SketchUp: hier op het forum zien we de hele tijd modellen voorbij komen die mislukken, omdat SketchUp fouten maakt: dat levert geen waterdichte, soliede modellen, maar eerder een soort kartonnen, in elkaar geplakte modellen met spleten tussen de aaneenzetten. Dat geeft gaten in de prints, of bedoelde gaten vallen weg, onbedoelde vlakken ontstaan, enz... Dat kost een hoop moeite om te repareren, als het al gaat. SketchUp is ontworpen voor visuele modellen, niet voor 3D-printen. Vandaar. Maar het is natuurlijk jouw keuze, als dat voor jou geen al te grote hinderpaal is... Mocht je toch ooit overwegen om iets anders te zoeken, zoek dan eerst naar demo-video's van gebruikers (niet alleen van fabrikanten), en kijk welke user-interface en workflow je bevalt.

Ik zou zeggen: begin met kleine testprintjes, die niet te complex zijn. Blijf bij de printer en kijk nauwkeurig toe terwijl hij bezig is, zodat je een goed idee krijgt hoe alles werkt, en hoe de normale situatie is. Begin vanaf de standaardsettings, die zijn behoorlijk goed. Verhoog en verlaag dan de temperatuur in stapjes van 5°C terwijl de print loopt, via het Tune-menu, om te zien hoe de printer en het materiaal reageren. Print nooit te heet, want dan ontbindt en verbrandt het materiaal in de nozzle. Print ook niet te koud, want dan smelt het niet voldoende, en gaat het aandrijfwieltje slippen over het filament, en daar een stuk uit wegschuren. Verhoog en verlaag ook de snelheid, en kijk wat dat doet op de vorm-nauwkeurigheid, en op de flow. Ikzelf print liever iets koeler en trager dan de standaardwaarden, omdat ik meestal tamelijk fijne modellen heb, en dat een betere kwaliteit geeft. Verder, bestudeer de diverse "bonding methods" om je model goed aan het glas te laten kleven: dat mag nooit loskomen en van het glas vallen, want dan krijg je een hoop "spaghetti". Neem een stabiele, non-slip tafel, zodat de printer stevig staat. Bewaar je filament in een afgesloten doos met vochtopslorper (het soort dat je in de microgolfoven kan drogen en hergebruiken). Begin met PLA als materiaal, tot je dat goed beheerst. (Maar laat die prints nooit in de auto in de zon liggen, want ze vervormen gegarandeerd boven 50°C, en dat haal je snel.) Ontwerp je modellen voor optimale printbaarheid: groot plat vlak onderaan, weinig of geen overhangen, geen te dunne wanden (niet dunner dan nozzle + 10%). Wellicht heb je al CAD-software. Zoniet, kies iets dat kan wat je nodig hebt, waarvan de user-interface je bevalt, dat makkelijk aan te leren is, en dat goed printbare modellen genereert. Vermijd SketchUp, dat geeft altijd problemen. Ikzelf gebruik DesignSpark Mechanical (gratis, vereist alleen registratie). Zie Youtube voor demo-video's. Dat zal het zo ongeveer zijn, denk ik, wat betreft de belangrijkste punten...

Exellent idea. The difference is quality is huge. This is a trick to remember.

Silver and pearl filaments contain particles that reflect light in different directions. It is the orientation of these particles that causes very visible lines. If you use a solid color that is not too high gloss, thus rather satin, and a little bit translucent (but only very slightly), the lines will be less visible. Another option would be to learn to live with this, consider it a normal aspect of 3D-printing. Like sand is rough, metal is shiny, etc... It's the way it is.

Years ago I described my more gentle atomic pull method, but it also had a couple of other tips that I use. The main difference with the standard method, is that mine is much more gentle, less hard on the machine, but with equally good results. Regarding the amount of black residu on this pulled-out piece, it looks like the nozzle needs additional cleaning indeed. See here: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/ After doing an atomic pull, you should be able to see through the nozzle from above.

If you make the baseplate a prism instead of flat, you could print it upside down. But the tip of the cone will always come out poor, due to insufficient cooling, so this will need some post-processing.

When doing an atomic pull, you can often see if that part is deformed: if the edge between nozzle and coupler in the pulled-out filament has a thick blob, it is for sure damaged. In the photos below, the bottom orange one looks pretty good: this is okay. The other orange ones are hard to say, because of the deformation due to pulling. The blue one starts to show a bit of thickening where the teflon coupler would be. But the white one at the bottom has a huge sort of "blob-ring": here the teflon coupler is totally gone and needs replacement.

Are the kathodes clamped in the mold, is it a sort of box, similar to a box for a camera filter or lens (e.g. UV-filter)? If so, I think I would rather go for something that can withstand rough handling during transport, and that still prints easy enough. PLA is hard but gets brittle, and snap-fits don't work well. Also it deforms in the sun, if left in a car, even in the trunk, outside of direct sunlight. It will keep deforming until the load and internal stresses are fully off. So, this might not be the best option? Maybe PET could be a choice, in its most natural color? The fact that it is (or can be) food-safe, means that it shouldn't release too much dangerous or agressive stuff. And it has enough flexibility to survive snap-fit lockings, and has enough temperature resistance to survive a car in the sun. It does not easily fracture when dropped. But vacuum can do weird things: apart from degassing, it can even chemically decompose materials: I have seen that under electron microscopes with some dental cements. I am not a chemist, so I have no idea if this is a factor with plastics?

It might depend on how deep the vacuum has to be? Not only the plasticizers might be a problem, but also water and plain air. For example nylon absorbs a lot of water very quickly, which means it goes through easily. Also, some plastics are not oil-tight nor airtight: oils and solvents might seep through, as well as atmospheric air. And what if it fractures? How big will it be, and how strong does it have to be? And what if it shatters: can that do harm or not? Big objects need to be incredibly strong. If it has to keep its vacuum for a longer time, I think you would best go for metal or glass. If it is actively kept under vacuum by a pump, I think any reasonably strong plastic might work? Your biggest problem might be how to print it airtight? Normally prints have huge amounts of tiny voids, canals, bubbles,... You will have to print very slow and in very thin layers to get it watertight, and on a single nozzle setting (no dissolvable supports). I once tried to print a filter for my vacuum pump, first at default settings. To test it, I put it under pressure with tap water, but the water jetted out via lots of tiny holes. After printing again slow, cool, and in the tinnest layers possible, it is now watertight, and it seems reasonably airtight too. But the rest of the system isn't: silicone-tubing is not vapour-tight at all, and not oil-tight either, and the pump probably isn't too, so I can't really test my filter alone.

If you would have compressed air, also blow out the SD-card slots in the computer and printer. Often hairs or dirt get in there, causing bad contacts and thereby similar problems, resulting in corrupt files.

Based on common sense and guestimating, I think the layer lines and voids in the print are going to be a 100x higher risk than the nozzle-composition. Nozzles don't melt into the print, unless you use very agressive materials. But the layer lines and voids will create areas where the bacteria will accumulate and breed, and you can't wash them out.

I can't interprete gcode and can't verify it. But in Cura's layer-view you can see which traject the nozzle is going to follow. If Cura is at error, then you should see those erratic movements in the preview to. Before saving any gcode, you should always inspect the preview. Does it show those problems too? I rather think that, depending on your machine and file-transfer method, the memory card is defect, or the file is corrupted, or the card's connector is dirty, or the USB-stick is defect or corrupt, or the communication gets interrupted or corrupted if via network or USB-cable, or the computer is too busy doing other things, etc. Something along that line of thinking...

I guess by "the thread leaning to the left" you mean that it is asymmetrical, like a sawtooth instead of a symmetrical triangle? If this model is printed standing upright, maybe this could be caused by the edges of the overhangs curling up? Some materials have a tendency to curl up on overhangs, due to the shrinking while cooling. Since a steep overhang is printed largely in the air, there is nothing to keep it down. See the photos below. Sometimes printing in very thin layers and as cool as possible might help. Sometimes thicker layers work better. Sometimes the curling up can be so bad that the nozzle bangs hard into the model, and damages it or knocks it off the bed. See the test prints below, which I designed for testing these limitations.

Something I forgot: Also ask the manufacturer (or ask other users) which items are considered replacables that wear out? In the early resin-printers of this type, the plastic transparent plate on which the model was built, wore out very quickly: it got opaque and scratched, after which good prints were no longer possible, since the light has to shine through this plate from the bottom. I don't know the life and status of current printers. So you should question about this, and ask prices of replacement parts. How many prints can you do on the same spot, or how many hours does it last, before it has to be replaced? Also ask what the life-expectancy is of the lamp, and the LCD-panel. Depending on the technology used they also might need replacement after x 1000 hours? Concerning the UV-screen: is that a separate cabinet, or separate lamp? Or is that only to protect you from the imaging LCD-panel? If a separate unit would be required, ask if it is included in the package. Maybe daylight can also be sufficient for post-curing some resins? This sort of things is why it would be good if you could come into contact with a user, or maybe a technical school, or product development department. They are far more likely to tell you the annoyances too. Maybe there is a forum for this printer, or similar models? Resin printers in general (I don't know this particular one), can give excellent results. But you have to be willing to deal with the liquid resin that will go everywhere, cleaning chemicals, waste, and precautions.

I do not know this particular printer, so what I wrote are the general issues with most of these printers, as far as I am aware. Printed models come out dripping wet with sticky resin, and that has to be rinsed off. Then supports need to be removed, if any, depending on the model. Whether it requires post-curing in an UV-station might depend on the printer and resin type, some do, some don't. I don't know for this one. You should ask the manufacturer: - Which cleaning solvents are required: chemical formula? Are these general products ("open source", sort of), or only from that company? - What is the exact post-processing method? - Is an UV- or other post-curing station required? If so, which specs? And from which manufacturers? - Which personal protection is required for handling the chemicals? (usually at least gloves, sometimes also air extraction due to chemical fumes, sometimes special chemical waste-handling procedures) Compare the data you get from the manufacturer with what you find searching on internet or Youtube, from real users and independant reviewers.

On Youtube you can find videos, if I remember well on channels of "CNC-kitchen", and "Maker's Muse", and others (I don't remember the names). These are indepentdent people (not company related) who have done lots of reviews of different products. These printers are getting a lot cheaper and more reliable now. The biggest drawback is that it is a huge mess: prints come out of sticky liquid, and they need to be rinsed in alcohol or similar solvents. This is messy, and creates chemical waste. Also, tiny supports need to be removed, but this should go easy. I don't know if this applies to all printers, but some prints need to be post-cured, after cleaning the model. The printing process only cures a fraction of the resin, the rest is cured in the post-curing. So you need to calculate-in these extra steps. The materials are light-cured, obviously, and they do get very brittle with time, especially in the sun. Under mechanical load, they tend to deform (at least the models I have), even worse than PLA. The huge advantage is that you can make extremely detailed models. Depending on the printer, steps can be so tiny that you almost can't see them, thus no layer lines. Also nearly transparent prints are possible. So I think for jewelry, model railroads and scenery, tiny figurines, detailed moulds for pouring silicone, and that sort of stuff, they can be really great, and well worth the effort. This is hard to do with an FDM printer. Not so much for functional parts that see some mechanical load. After reviewing the Youtube vids, try getting a little bit of the resin, and experiment curing that in daylight / sunlight / LED-spots. Just to see how it reacts and feels, and how hard, stable and brittle it gets, and how easy it is to machine and paint. Also try to get a demo-model from a manufacturer or distributor. Best is to go to a independant distributor in your environment, who has printers from all different brands and technologies on display. Maybe you can get him to make a print, if you offer to pay for the costs. I am talking about the tiny printers here, with usually build volumes of ca. 15cm^3, which cost 500...2000$. Not about industrial 100.000$ machines. I do not have such a printer, but collegues have. This is my view, but of course other people may have different views.

Before doing a whole mask, I would suggest to do a test model first. Start with default settings or proven settings from other people, and then on the fly change temperature and speed, and see what effects that has on your model. Different brands, material compositions and colors may all have an effect, as well as environmental circumstances (e.g. moisture).

I have come across this terminology in manuals of power supplies, especially high-power units with separate sense-lines. If the ground-wire is too long or too thin, you can get a significant voltage drop across this line. Let's say the ground line has a resistance of 0.1ohm, and the current is 10A. Then you get a voltage of 1V across the ground-line. So the "ground" at the electronics board is 1V higher than at the supply. This was the definition of "ground level shifting". Hense the sense-lines in the power supply, which needed to be connected as close to the board as possible. The concept is also mentioned in manuals of analog to digital conversions, and precision measurements of National Instruments boards, but I don't remember if they used this terminology? But this effect can also happen within boards, if the wires are rather thin, or the currents are high. So, if there is a sensor that uses a common ground path with a power-eating source, then that ground level shifting could cause significant errors if the sensor works in the mV range. Power- and measurement-circuits need separate wiring, which should only connect at one point close to the supply (if using a common supply). I don't know the layout of the UM-boards, so I don't know if this effect plays a role here. But it is a theoretical possibility. And the difference in quality with bed on and bed off, seems to point in this direction, although there could still be other issues of course. And indeed, you can not measure this effect in a closed loop system by measuring the voltages in the system, since the regulation tries to adjust the situation to always read the same sensor-voltages. You need an independant temperature sensor with independant power supply (e.g. battery powered), parallel to the system under test. Basically a separate sensor or thermistor that you connect to the nozzle. Power supplies with separate sense lines were required in the age of mainframe computers, because they would draw enormous amounts of current, and the supplies were located quite far away from the electronics boards. Power wires could easily be 3m long, or more, so you would get a huge voltage drop across these lines. Anyone working on the wiring of such old mainframe computers, had to be aware of this concept. For example, the Aesthedes graphics computer shown below from the 1980's had two +5V 40A power supplies, one +12V 15A, and one -12V 2A, all loaded close to their maximum, so that is almost 80A on the 5V line. But when PCs came along, the importance of sense lines dropped, so I don't know if they are still used today (I haven't done much electronics the last years).

Long ago there has been a discussion if the heated bed could be the cause? If it would draw so much power that the ground-level (zero volt) would shift up, and if the temperature sensor would use that same ground wiring, this could cause errors in the temperature the main board "sees". And then it would adjust incorrectly. But I don't remember exactly on what printer models this was (maybe UM2?), and what the conclusions or solutions were. Maybe you can find that again. It was several years ago. If you could print the same object on a cold bed, using glue, maybe you could rule this out? Then at least any ground-level shifting can't come from the bed. It could still come from the nozzle-heater, but that draws less power, so should have less effect. If this would be the cause, of course. Could be something entirely different also.

Yes sure, anything according to that concept. As long as it separates your hands from the door handle, and it doesn't contaminate your pockets! This is why I wanted a cylindrical object, not an open flat one like most others, so the inside would not touch your pocket lining. My first idea was using left-over pieces of copper tubing, rain/drain-pipe, aquarium-tubing,... Copper tubing would have the advantage of being self-desinfecting: its oxide outer layer is poisonous and soon kills germs; it is sturdy, easy to machine, and can easily be further desinfected or autoclaved if required. Maybe copper-filled filament would also work, but then you lose the heat-resistance. Cutting plastic PVC-table cloth, rolling it up in a cylinder, and glueing or sewing together (whatever works on that plastic), also crossed my mind. So, if you have little ziplock bags, or other sleeves, that should be fine, provided it is handy enough. This below was the original idea, to be made from a piece of rain-pipe. And then it evolved into the "vase", since I don't have piping but I do have a 3D-printer:

I designed a cover that separates care givers from contaminated door handles. The idea is that you carry this cover with you all the time, and slide it over a door handle to open the door without touching it. It protects you from contamination by dirty door handles, and vice-versa. You only touch the outside of this cover, and the door handles only touch the inside of this cover. There do exist lots of other means, but this one provides the best separation, as far as I have seen. And it can stand up vertically (it has to be printed this way), and can be re-used as a little vase, when the crisis is over. Obviously, every person should carry their own, and not share (that would defy the purpose). It can be desinfected and re-used. It fits straight door handles up to 21mm diameter. I designed it for use in our own labs and hospital, not only for the corona-stuff, but also for other chemical or biological contaminations during experiments or dissections. People tend to use gloves when doing experiments, and then they walk around opening doors with their dirty gloves, spreading more contamination than they would without gloves... This simple tool can help. Would you be interested in this too? If yes, I could upload the design files and STL-files. But I might require you to think about a couple of questions, before you are allowed to use it. (Click on the image to enlarge it.)

She looks like sun-burnt now. :-) I was thinking, for simple models you could make an inverse as mould, and pour gypsum into it. Gypsum is a lot easier to sand than plastic, and its stone-like structure hides small defects and layer lines. Then you would have a solid heavy-weight gypsum girl. But that method won't work for this model, because she has way too much undercuts in the hair, and in her fine hands and arms: even with a complex multi-part mould, it wouldn't go. PS: I didn't do any "heat-acetoning" myself. I had considered it, but I didn't want to explode, so I dropped the idea. :-) But I have seen quite a few Youtube videos of it. However, I did both "acetoning" and "heat-treatment", but separately and on different models. For heat-treatment I tried annealing (60...80°C) in a lab-oven, to remove stresses and to increase temperature resistance. But this does not work well for me: the models did shrink in length and expanded in width and height, so they didn't fit anymore. It might work for art though, not sure. If you could get the stresses out from the printing and uneven cooling, it is less likely to split. The heating and cooling should be done *very slowly*, so everything has time to settle. If you don't have a computer-controlled oven, I think it is best to do this on a manually heated build-plate in the printer, and cover front and top with plastic. Or put a little box over the model. I also tried a heat gun to smooth, because this did work well on vacuum thermoformed models in the past (it was the officially recommended method). But this does *not at all* work on 3D-prints: it melts the outer layer (as desired), but it also heats up the entrapped air bubbles, so they explode and cause little craters on the surface. Making it much worse than before. Similar to printing wet nylon, but even more ugly. And it causes brown burnt spots. So I don' do heat-treatment anymore. For smoothing I tried dipping testmodels into acetone for some time, but this caused huge cracks, even diagonally through layers (not following the lines), and weakens the plastic and basically destroys it. So the only smoothing method that I use now and that works very well, is yours: brushing-on acetone. And then I wipe it with paper tissue to remove the whiteness, before it is completely dry. Then I can get off most of the white residu. Sometimes I do a second brush, but that doesn't seem to improve smoothness very much anymore.