geert_2
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Posts posted by geert_2
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I have measured the glass temp with an infrared thermometer (they are not too expensive: ca. 30 euro), on both of my UM2. If the glass is warmed up well (without printing, without model), the temp was reasonably uniform. Except on the edges, where the last few centimeters (an inch) would be 5°C cooler on a 60°C bed, and 10°C cooler on a 90°C bed. Aluminum is very conductive, so the aluminum plate should provide a good temperature distribution. But the upwards air flow around the bed will cool the edges much more than the center: I think that is the main reason.
However, as soon as I started printing, and the fans came on (PLA), there was a huge drop in temperature in the area where the head wais printing. At first I was surprised. But then, yeah, it seems logical: the purpose of the fans is to cool, so that is what they do...
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Concerning the cone, as gr5 said you have not enough cooling. What I use as solution is to print a dummy next to the real models. See the examples below for the explanation.
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12 hours ago, cloakfiend said:
It looks nice and sharp on the edges which i always look for in smooth looking models. I always wanted to cast metal but i want larger stuff and i want it perfect. Is that possible without a pressure mold or vacuum? And just a cheap home setup?
I don't know for silver, but on Youtube you find lots of videos of people casting aluminum in a relatively cheap home setup. Very interesting. It takes a gas burner, a furnace, a wood box, special casting sand, and a few spoons. And of course fire-resistant safety wear: helmet with face mask, body covering suit, thick gloves, shoes: this is probably the most expensive. So that you won't get hurt if the hot metal would explode like a volcano, due to steam formation if you accidentally pour it into a wet mould. And then you only need gas (acetylene?) and scrap aluminum. And a garden and reasonably good weather (not too wet). Maybe the last one is the most difficult to order here in Western Europe.
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On 3/13/2018 at 5:42 PM, cloakfiend said:
If you saw my camera setup, you would laugh!
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I consider simple methods that work well and produce excellent results, more advanced than "high-tech" methods that don't work. So I would rather learn from those simplistic methods...
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I have done several tests with transparent PET, ICE brand. I found that the results are better when printing slow: 25mm/s, so that the the flow is very regular, and the material has time to flow into all corners. Printing at the cooler end of the range also helped. I don't know why, since I expected the opposite. Printing at medium temps caused more opaqueness, and printing hotter was more transparent again, but it caused too much accumulation on the nozzle indeed.
I also noticed that transparent light grey filament looks more transparent than water clear, colorless filament. The water clear becomes bright white due to the reflections and refractions. But the grey filament seems to absorb some of that light, and thus reflects less. Also yellow looks more transparent than colorless, probably for the same reason.
I also read that in PET the crystal structure may have an influence on transparency. And that crystal structure could change with age, temperature, moisture and processing methods. If NGEN is something polyester-like, I can imagine that this might also play a role. Of course, too much moisture will allways cause little steam bubbles inside the extruded sausages, or craters popping open on the surface, and it will make it less transparent. Under my microscope I can clearly see those bubbles in the sausages.
But anyway, the transparency lasts only a few layers, and then it becomes translucent indeed, due to the light reflections caused by the trapped air in-between the sausages. I got nowhere close to the tests of |Robert|.
So these sorts of "transparent" filament are very usefull for making hollowed-out text inside the model, like company logos or copyright info: if close to the bottom, it shines through good enough. But it is useless for lenses.
Have a look at these examples. If I remember well, the "TOP SIDE" text was 1mm high, sitting 0.5mm below the surface. Both photos are yellow and red ICE PET. It won't get much better than that with PET.
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I don't have an UMO, and I don't know its mechanics, so it is difficult to draw conclusions.
However, if this would be done on an UM2, then I would first look into possible causes for underextrusion. For example a deformed teflon coupler in the nozzle (don't know if the UMO has one?), a feeder or feeder drive-wheel slipping or dirty, bad temperature control (e.g. loose sensor), partially blocked nozzle, low-quality filament with variable diameter, filament stuck on the spool or wound too tightly near the end, and similar things that might cause irregular extrusion.
And only then I would look into bed leveling, for fine-tuning the result. But I don't think this is the main problem here.
Normally you should be able to get shiny, almost totally flat undersides, with hardly visible layer lines. Like in the best parts of your photo, but then everywhere. Or like this photo below. See the long name plate with copyright info (center-right): the text is hollowed-out inside the material and shines through the flat bottom, which is almost as glossy as a mirror. You can see the window reflecting in it. This material is tranparent PETG, but for PLA is should be equally smooth.
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For most models, I disable all automatic supports in Cura. And I design my own custom supports in the CAD-program, as part of the design. This is because of the special features of my models: often the models are quite small, or with difficult to access areas. This is for UM2, with one nozzle.
The blue support in the first pic above is ca. 10mm wide. The red/orange support in the second pic, center-left, is even smaller: it is too small to get into it with a knife. So I have to extend the supports so I can grab them with pliers.
The first times it takes trial and error, but after a while you know what works and you can design them right from the beginning.
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Maybe you should not only show the 3D-printing process, but also the reason why one would use it? To really make the physical objects of things that you have designed by yourself. So that the subject has a real purpose for them, it is something they can really use.
I think a few short videos on 3D-editing would be great: they show how a model is created from scratch, and how easy it is once you understand the basic concepts.
Maybe you could have a look at videos or webinars from DesignSpark Mechanical: this is freeware, so every student can download and use it himself. It only requires registration (which is a more than fair price for the value you get).
Or have a look at Form-Z webinars. This is not freeware, but in the past they had free educative versions. I don't know today. And their webinars were quite good and pleasant to watch.
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Also, in the photos, the black background and the mirror-effect fit very well to these shiny models. Also the light is good. If you don't mind, I woul like to see a photo of your photo-stand setup, including the lights.
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For PLA, printing cooler and slower usually helps for me on our UM2. Also, I use ribs on top of my supports (=0.5mm wide ribs with 1mm horizontal gaps in-between, for a 0.4mm nozzle): these make removal easier, but still give good underside quality. Most of the time I use a vertical gap of 0.2mm to 0.3mm between support and overhanging part.
And I provide all sorts of methods to make support removal easier: gaps to wiggle supports loose, holes to insert pliers or hooks to pull out the supports, protruding areas where I can push with my fingers, etc...When designing the support, I calculate all this in from the beginning.
For a few examples, see below. Some are parts of real designs, some are test pieces to try what worked best.
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22 minutes ago, cloakfiend said:
Thanks i polished it up and printed another for a visual comparison...
There is a beautiful light in this model.
Instead of plating with real metal, have you ever tried spraying with chrome-like paints? Like those used to give plastic car wheels a chrome look? And if yes, did that work? Maybe you already wrote about it, but I don't remember.
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This is probably not the answer you were looking for, but if I want things like this, for example to prevent a thin tall tower from falling over, then I usually design it in my CAD models.
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You might want to look at your models under a microscope, if you have one available. Or make pictures with a camera with good macro. It might help finding the cause of the opaqueness. If you see tiny bubbles or milk *inside* of the extruded sausages, or sort of craters that popped open on the surface, then it is probably moisture, and then you need to thoroughly dry your filament. If there are no bubbles or craters, and the sausages are fully transparant, but the whiteness is caused by the air trapped between sausages, then you need to improve the filling while printing, by improving the flow.
If I remember well, user |Robert| also tried printing a transparant block, with good results. Maybe you can find his post back for his settings?
Personally, I would try to print test blocks of 10mm x 10mm x 10mm, with various settings: starting at a low speed of 20mm/s (to get good flow into all corners and voids) and at a lower temp (to avoid burning the material). For PLA and PETG this usually works, but I have never printed with this material, so I don't know here.
In PETG I have also seen material accumulating on the outside of the nozzle, and then sagging onto the print. This seems to be because it is more rubbery and sticky than PLA, which is more liquid like yoghurt. Printing cooler helped here too: it did not totally prevent the accumulation, but at least it didn't get brown.
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This is a nice building.
What material did you print it in, woodfill?
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When we were back in school, looooong ago :), we were not allowed near critical lab equipment unless we passed a test on how to use it. So, anyone who was not prepared well for the lab session, could immediately return home, and could "come back in september". This tradition worked well.
For the lab technicians and supervisors, I would recommend: before using any new equipment for serious work, first play around with it until you know it down cold. In case of a 3D-printer: have fun printing keychains and all sorts of little toys until you have your bonding methods, temperatures, and all other critical material settings correct. This playtime pays off really well. If you don't spend time playing around first, you will spend 10x more time while wasting real models later on. This is sort of a law of nature. But of course no one believes this, so they neglect the playtime, and they spend 10x more later on...
For getting the bonding-methods correct, a little testprint like this might help: if you can print this thing well, without any corners lifting, the majority of normal prints will also print well. And if this test fails really soon and produces spaghetti, you are likely to have bonding failures in other models too. Feel free to use this one, or to derive your own version of it. Be sure to stay with the printer while doing this test.
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If you have 1 in 15 parts coming loose, then I would suggest you review your bonding method: there is a lot of room for improvement. Improving your bonding method until it is 99.99% safe will give you a lot more peace of mind; it is definitely worth the effort.
I have maybe 1 in 2000 parts coming loose, even though my models are not always easy to print, and even though I don't particularly care about cleaning the build plate.
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17 hours ago, kmanstudios said:
It ain't water tight though. I am trying to find a way to make a vase that is watertight on the inside to hold real flowers, but have the sugared effect on the outside. I will say this though, it really, really chews up filament like you would not believe.
Maybe coat the inside with polyurethane, although this could have a visual effect? Or simply put a plastic PET bottle in it, maybe a 33cl bottle, like a coke-bottle where you cut-off the top?
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4 minutes ago, SandervG said:
Hi @geert_2 thank you for your feedback! I have had it too a few times. For me refreshing the page always helped and with this new forum software, my post has always been saved and I could just continue my message
Have you tried this as well?
I haven't tried that this afternoon when I had a stubborn cursor, but I will try next time. Thanks for the feedback.
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Sometimes while typing, the cursor jumps to a random position somewhere else in the text, and it starts typing from there. Instead from where I was actually typing. For example while typing on line 12, it may suddenly jump to line 5 halfway a sentence, and continue from there. This mostly happens after inserting a smiley by typing a colon and a bracket, which is then auto-replaced by a real smiley a few lines later. But it also happens on other moments, usually after making a few edits. This is annoying, since of course it messes up the sentences. But this also disables going back to the point where I want to type: the cursor keeps jumping away from where I want to type, to somewhere else; it just refuses to stay where I put it. Sometimes I have to delete a whole paragraph and type it in again, simply because the cursor does not let me edit it. So I would suggest you remove all automatic tools that try to interprete our texts while typing, we don't need Big Brother "autocorrecting" our texts into garbage, à la Microsoft Word.
Edit: forgot to say: system is Windows 7, SP1; and browser is Pale Moon, most recent version. (Pale Moon is a Firefox split-off that kept the old-style decent menus, when the Firefox user-interface people went insane and abandoned all established user-interface guidelines.)
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If you directly edit files in the "program files" folder, or in the root of the harddisk, Windows sometimes moves them behind your back into a totally different subdirectory somewhere else, called "virtualstore", deep down in your *personal* files. I don't remember the exact location, so you need to google for it.
The purpose of this was to prevent people from messing up their "program files" folder; but this weird method rather messes up way more than it solves, because obviously a lot of programs and people can't find their files anymore.
Another thing is that system protection may revert any changes to system files - or what it considers system files - upon the next system reboot.
Could one of these two things be the reason why the changes you make "don't stick"?
You should be able to prevent this weirdness by disabling system protection, then make all the required changes, and then enable system protection again.
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Another option: if your prints are not too long, manually unwind a bit of filament and straighten it. I do this by winding it in the opposite direction around a skater wheel of 7cm diameter. Then unwind a bit more, and straighten it. Until you have done a few meters. This takes only a few minutes, while the printer is warming up anyway. Then roll the filament up again, but now it will sit loose on the spool.
Additionally, if you have colorFabb spools - or identical ones - you could print one of these clamps and use that to prevent filament getting stuck under itself while in storage, and to prevent it from falling off the spool while printing. When the while thumbwheel screws are present, they lock the filament. When absent, the clamp can slide freely along the edge of the spool, and thus prevents filament from falling off sideways, unwinding itself and producing a huge ball of 3mm spaghetti. Feel free to derive your own version of this.
For the STL-files and RSDOC-files, see here (scroll down a bit):
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
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So basically you want to print spaghetti, is that correct? I am a bit curious what the purpose is?
Another method to achieve this might be to raise the design in your CAD editor to the required height. And then at a heigth of 0 add a little square, e.g. 10mm x 10mm, out of the way. So that square will sit on the glass, and the real design will be in the air. And switch off supports.
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Search on Youtube for mould making and casting. There are a lot of companies promoting their materials with how-to videos. From there you can find their company websites and product specs.
In the Netherlands in Amsterdam, there is a big shop for modeling, moulding and casting materials and tools. They have it all: clay, plasticine, plaster, silicones, lots of composites, colors, etc... And they have downloadable catalogs with some explanation. See: https://www.formx.nl/
Maybe this could give some inspiration?
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In old Cura versions you could set the wall thickness to for example 5mm (at least more than your walls), and that would give the desired behaviour. I haven't used recent versions yet, but I think it should also be there somewhere?
Sterling silver pendant
in What have you made
Posted
Out of curiosity: if you cast larger pieces in bronze, do you cast a bronze shell only (=similar to "no infill" in 3D-printing)? Or do you cast them fully massive (=100% infill)? And if filled, do you have problems that the models crack due to uneven shrinking? I heard from an artist that this could sometimes be an issue in large models like statues. He made the clay models and silicone and plaster moulds (for the wax model), but he did not do the bronze casting himself, he went to a professional company for that. Some of his statues were 0.5 to 1 meter high.