geert_2
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Posts posted by geert_2
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Another option might be to print the thread a little bit too small, so it does not fit. Or print the model without any thread. Then warm it up in an oven (only if electronically controlled), or on the build plate to about 70...80°C, screw it on the equipment immediately, and let it cool to room temp. In this way I have made difficult designs fit around clamps, although without threads. Expect it to take a few trials, or try on obsolete equipment first. Make sure your photo equipment has metal threads, no plastic ones.
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For single-nozzle printers like the UM2, the gap depends on the size of your model, and on the quality you want at the underside of the model. And on printing temperature and material. So it is to a large degree a question of trial and error. Smaller models can have a smaller gap. But for large models, the supports may become difficult to remove if the gap is too small. (I have no experience with UM3 dual nozzle printers, so I can't comment on that.)
I usually take 0.2 to 0.3mm gaps for my models. On top of the support, I design ribs of 0.5mm wide, with gaps inbetween of 1mm. This reduces the contact area, makes removal easier, but still gives a good surface quality. Sideways I leave gaps of ca. 1mm, to prevent the supports getting glued to the walls of the model. Also make sure the support sticks well to the glass, thus give it a wide and solid base plate of for example 0.5mm thick. Single lines don't stick well.
And, very important: make sure you build in ways to remove the support: provide holes to insert hooks and pliers to grab them, provide areas where you can push or pull manually, make slits so you can wiggle all parts loose, and so on. Sometimes custom support design takes as much time as designing the model itself.
For small models, you could also optimise supports to provide additional cooling time for the real layer, to reduce heat deformation.
Make a small test model where you incorporate all sorts of methods, and try what works best for your models, temperatures, and materials.
Sometimes I prefer tree-shaped supports, sometimes I prefer separate layers that can be peeled off easily layer by layer. It depends on the model and on how accessible the area is.
Practically, sometimes the easiest way to start is to copy the overhanging surface of the model, offset it 0.3mm (or whatever distance you like), and start modeling the support from there. This works well for irregular overhanging parts. Or start from a sideways view, draw the supports, and extrude this into 3D. This works well for tree-shaped supports.
See these pics for ideas. I use these methods in real models:
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56 minutes ago, yellowshark said:
tell them it cannot be done and then let them have a discussion with your CEO as to which department is more important to the Company. PLA requirement is to be printed cool. We have printed PLA mostly, for 4+ years, and always leave the door open and remove the lid (they are for ABS). To date we all still have 8 fingers, two thumbs and two lungs.
I feel the same, but the problem with this is that in case of accidents, it will be the management and safety-people who are prosecuted in court. So, from their viewpoint, their safety from being prosecuted is way more important than your printing quality. Judges are so unpredictable and sometimes so irrational here, that common sense is not always an option. At least, that is how they feel. I know a situation where a manager had to go to court, because one of the employees in his chemical plant committed suicide by jumping off an installation, after taking an overdose of pills, due to marriage problems. The reasoning: "It shouldn't have been possible to jump off installations". In the end he wasn't sentenced, but it still was a heavy experience.
Another option might be to demonstrate that getting stuck between the moving rods, doesn't hurt at all. The stepper motors do not have enough force. When they can't move, they simply skip steps and ruin your print, and your mood, but that's all. Don't ask me how I know.
I wanted to remove a hair while it was printing, and I just sort of forgot that it could suddenly move...
It's not like hydraulics which can have tons of force. It is more like a toy.
I would rather consider it a safety feature that you can grab the print head and stop it, in case something goes wrong.
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If the problem (according to the safety-people) is risk of accidentally touching moving parts or hot parts: what about installing metal chicken wire, instead of a full enclosure? Then people cannot get in with their hands, but it allows normal airflow?
I don't know if "chicken wire" is a good English word, but I mean the steel wires used to keep chicken, rabbits, rats, birds, etc..., out of a garden. It is just steel wire with holes of a few centimeters. Or something similar.
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I noticed that your tables do have wheels, and the frames are rather thin. Usually such tables are not as stable as fixed tables, at least not the ones I have seen here. So, do they wiggle when you touch them or hit them, or are they rock-solid?
If they wiggle, maybe they came into resonance while printing a specific part of the model, and this resonance was just enough to make the printer move?
If Nicola Tesla could destroy a whole building with a little device as big as a cigar box, due to resonance, then I could imagine resonance can make a printer move too? Also you might google in Youtube for films of the Tacoma bridge coming into resonance, swinging meters up and down like rubber, and finally collapsing after an hour or so. In only moderate winds.
Anyway, be sure to put a rubber anti-slip mat under it. The ones that have a very sticky feel should work well, and they reduce sound as an added benefit. If I were in your place, I would also glue or screw a little border around the table, so nothing can roll off or slide off.
We do not disbelieve you, but in problem solving, when we try to comprehend what happened, we look at the most logical reasons first. And kids or pets throwing something off a table are way more likely than a printer walking around due to resonance (or whatever else). So we need to eliminate the logical causes first. That is all. Don't take it personally, it's just technical.
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I think you would best post a couple of photos of the print, both a general overview, and close-ups. Anyway, expect the holes to become smaller than designed, due to the elasticity of the molten material when the nozzle draws the outline of the holes: it is pulled inwards. Just like a rubber band would be pulled inwards, if you try to lay it down in a circle and apply a bit of force to it. The smaller the hole, the worse this effect is. So, a 3mm hole is likely to end up as a 2 to 2.5mm hole.
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6 hours ago, cloakfiend said:
@geert_2 lol about the eyes. Someone already told me off about dead eyes a while ago, it was probably you. The problem is i never save eyes so always have to do them last and if im happy with the rest I kind of leave the eyes as thet were when i finished the rest. Eyes still annoy me, used to be lips but its now eyes. Hard to get right especially with people you know...
Yes, it could have been me. I vaguely remember I once said that "blind eyes" were the only thing that could be improved. It might have been on one of your early sculptures?
Eyes are probably the most difficult part of any portrait, as they define most of the facial expression and personality. I tried it a few times in plasticine, but never got it right. So I "solved" this by not modeling the eyes at all, even not "blind eyes". I made just a little indent where the eyes are supposed to be, and let people fill them in with their own fantasy.
Anyway, for inspiration on how to sculpt the highlights and shadows in the eyes, I would suggest you have a look at sculpting videos of Philippe Faraut on Youtube. Although there are lots of great artists on the internet, including you, concerning eyes and facial expressions Philippe Faraut is top. Especially his clay sculptures. His portraits of depressed, cynical, disturbed and angry people are so real that you can taste the mood and character of the person. Several of his demos got more than a million views.
Have a look at these:
https://www.youtube.com/watch?v=S2aYaM7WYBk
https://www.youtube.com/watch?v=yghUZ7qiXFo
https://www.youtube.com/watch?v=dY80JT_sb-U
https://www.youtube.com/watch?v=FA6jwWuc61o
https://philippefaraut.com/collections/portrait-sculpture
https://www.youtube.com/results?search_query=Philippe+Faraut -
In the beginning, 2 years ago, I did several tests on the effect of bed temp on bonding of PLA.
At 60°C bonding was optimal for me.
At lower temps, for average objects usually it still worked well until 50°C. However, at 40°C models were likely to pop-off suddenly, with a loud snap, in mid-print. Below 30°C there was no bonding at all, for my models.
At higher temps at 70°C the PLA became too soft. And then corners would lift and be peeled off the bed, due to the shrinking forces from the layers above, and the whole model would warp and come off.
Thus a balance has to be found between hot enough for a good bonding, and not too hot so it does not stay too soft. The default value of 60°C for PLA seems to work best on both of my UM2. These tests were done on light blue Ultimaker PLA, and on colorFabb white and orange PLA/PHA, but they seem to be valid for other Ultimaker and colorFabb PLA too.
As bonding agent for PLA I only used my "salt method", because this worked better than the glue stick at that time. But back then I didn't know yet how thick the glue layer had to be (probably I made it too thick?), and I did not wipe the glue with a wet tissue afterwards, which seems to equalise the glue into a very thin layer and improves bonding.
For PET (or is it PETG) from ICE, a bed temp of 90°C seems to work best for me.
Before printing real objects, I recommend you design an inverted prism, with a very small ground base, and wide top. This excerts huge warping forces on a very small base, due to the overhangs. And the edges curl up, causing the nozzle to bang into them. So it is a very hard bonding test. Print this model with various bonding methods, and bed temps, stay with the printer (!!!!), and carefully watch what happens, and try which bonding method works best for you. If you can print such extremes well, it should work for average models too. I could not print this test with the glue stick, nor on a bare glass plate: the models came off and produced spaghetti. But it worked with the salt method, although edges did lift, so it was on the edge.
Picture of a sort of inverted prism being printed. If I remember well, the base was only 2mm wide, but the top was going to be 10mm wide, and somewhere around 5 or 6mm high. And as you can see, at that time I also didn't know about atomic pulls and about worn-out white teflon couplers, so there is a little bit of underextrusion.
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That white plastic cover in front of the nozzles, is it needed for technical reasons? Or is it just for aesthetics? Because, if it would not be needed and if it would be left out, any build-up of molten filament would have more room to escape to the front? So maybe it wouldn't go up? Or am I missing something? (I don't have an UM3, so no personal experience.)
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Or else, try to drill a small hole in the break away material. Manually, so you have good feeling, and you don't heat and melt the PLA. Then screw a wood screw in the hole, and then carefully wiggle, rotate, and pull on the wood screw. So you use the screw as a long lever. We have used this method to remove broken plastic screws from their holes. If you are not sure, try the method on a small test piece first.
If you have one, you could also use a screw extraction kit, which specially designed to remove such broken parts (screws) in small holes.
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If you want to remove the horse-shoe clips and bowden tube much easier, print these clips. You can easily grab them with your fingers. Find the models on my page (scroll down until you see them):
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
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If you want to make it a lot easier to remove the bowden tube next time, print a couple of these horse-shoe clips. Their base has the same dimensions as the original ones, but these are very easy to grab.
You can find the models on my page here (scroll down until you find them):
https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
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This is really impressive, the sort of picture where you keep looking at. I also noticed he has real eyes, not blind eyes. Good.
Aside, out of curiosity: do you have any experience how long such a plating survives? Does it stick well to the plastic and can it handle abuse? Or do you have to be very carefull not to scratch?
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On 2/15/2018 at 4:30 PM, gr5 said:
Another cool trick would be to print peek as support material except for the interface layer. Then put a layer of PLA way up high in the print where the support meets the main material. It would be a thin layer interface. Then when done you could heat the whole print to 100C and the supports will just fall off.
I don't think cura supports this feature but people have asked for it - they want 90% of their support printed with PLA and only the interface layer printed with PVA. This doesn't work well with PVA as PLA sticks well on top of PVA but PVA doesn't stick so well on top of PLA. With nylon and PVA I think this would work great. But again - not sure that cura supports this idea.
Maybe you could simulate this by designing such custom supports in your CAD model? And switch off all supports in Cura? Then you can give any shape you want to the supports in the main material, and to the thin interface-layer in the second material?
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I do not have an UM2+, only the UM2 non-plus, so this is just general guessing.
It looks like the heat travels up too high in the nozzle. So maybe you first need to check if the little fan works well? The one blowing on the filament and nozzle, which should prevent the heat from traveling upward? There could be strings of filament stuck in it.
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Wouldn't it fit in the printer diagonally, if you cut off the end parts, the support stands, and only keep the tubes? That might print faster and in better quality for the little tubes? And then only print the end parts and the supports vertically?
I am surprised that it doesn't fall over, for such a high but narrow print.
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7 hours ago, gr5 said:
All ultimaker printers use "3mm" filament which is actually 3.85mm.
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This is a typo, it should be 2.85mm. I am sure gr5 was thinking "2.85mm", but his finger hit the wrong key. This happens with fingers when they are typing in half-automatic mode, while we are already thinking way ahead about the next thing.
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For such small items I always use this method (see pictures). If you make the dummy 1 layer higher than the real model, this method also prevents the blob from occuring on the models (they will be on the dummy, if any).
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Try these concepts. I am using them constantly with good success.
This last picture shows the difference between using a dummy and not (numbers are cm, thin lines are mm).
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1 hour ago, Zach - Art Education said:
Intriguing thought, but I may get into legal trouble if I try to sell off school property!
I would rather keep the UM2+, and have school buy a second one.
If the goal is to print as much models as possible in one shot, then a larger build area seems beneficial?
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De nozzle op 230°C voor PLA lijkt mij nogal veel, tenzij je snel print, of in een dikke layers. Anders is de kans groot dat het snel gaat aanbakken in de nozzle.
Ik gebruik meestal 210°C bij 50mm/s en 0.1mm layers. En 185 à 200°C voor 25 à 30mm/s bij 0.1mm layers. Bed altijd op 60°C: als het kouder is, kan het model er af springen; als het hoger is, blijft het PLA te zacht en kan het model van het bed lospellen door kromtrekken. Tenminste, dat is mijn ervaring, maar het kan natuurlijk anders zijn bij andere mensen in andere omstandigheden.
De verhouding zout / water is niet kritisch: ik neem gewoon een oude glazen confituurpot, doe daar lauw water in, dan een lepel zout, deksel erop, schudden, en klaar. En dan bewaar ik het in de ijskast. Op kamertemperatuur gaat misschien ook, maar ik heb nu eenmaal die ijskast voor allerlei potjes en producten.
Blijf de eerste keren wel bij je printer, tot je zeker weet dat het goed werkt en dat er geen andere problemen zijn.
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In addition to lowering the bed temp, also check if the cooling fans do come on correctly? Not on the first layer, but then they should gradually start, and blow full power after a couple of layers (at least, that is what they do on my UM2, and this works well).
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Het is moeilijk met zekerheid te zeggen, maar zo op het eerste zicht lijkt de nozzle een beetje te ver van de plaat te staan. Dus het worstje is nogal rond ipv. echt platgedrukt? Zou dat kunnen? Probeer dat misschien eerst eens bij te regelen door de schroefwieltjes onderaan de glasplaat een kwartslag te draaien, terwijl de eerste laag geprint wordt. Ik controleer de dikte gewoonlijk terwijl het skirt geprint wordt (=outline rondom het model, op een paar mm afstand ervan). Ik print gewoonlijk drie lijnen skirt, net om dit te controleren en om tijd te hebben om het bij te regelen.
Verder raden sommige users aan om de lijm na het aanbrengen uit te smeren met een vochtig of nat doek, tot een zeer dunne gelijkmatige laag. Te dik of onregelmatig werkt niet goed.
User gr5 gebruikt een oplossing van 10% witte houtlijm in water; user neotko gebruikt haarlak, sommige anderen gebruiken 3DLac voor de hechting.
Ik zelf reinig de glasplaat met een doekje met *zout* water. Na het drogen blijft daar een bijna onzichtbaar, zeer dun laagje zout op liggen. Ziet eruit alsof het glas een beetje stoffig is, zoals een wijnglas dat een heel jaar in de kast gestaan heeft. Dat geeft bij mij zeer goede hechting, zonder lijm, mits de glasplaat op 60°C is. Zodra ze afkoelt tot 25°C, vallen de modellen er vanzelf af. Waarom zout goed hecht, weet ik nog altijd niet, maar het werkt al twee jaar super (maar alleen voor PLA, niet voor ABS, PET, enz...). Voor de volledige handleiding, zie mijn site (en scroll daar een beetje omlaag): https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/
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If the cause is not clear, maybe you could try along this line: first try to use a "known good" filament, which gave no problems in the past. Carefully watch what happens while printing, at exact which moment the blobs appear, and why. Sometimes you can see what is going on. And then, on the fly adjust all sorts of parameters a bit up and down, one by one: temp, speed, fans, material flow? Set each one back to default before changing the next.
Of course, also check if the nozzles are clean (do atomic pulls), if the feeder wheel and traject are clean, if feeder pressure is correct, and if the whole feeding traject flows smoothly. And check filament diameter. I could imagine that this sort of problems could be caused by irregular feeding: pressure somewhere in the feeding traject building up, and then suddenly jerking forward. Or a piece of filament stuck in the knurls of the feeder wheel, causing an irregular diameter.
If none of this helps, maybe you could design a new model with the same outer dimensions in a simple editor of your choice? I would suggest DesignSpark Mechanical: easy to learn, powerfull, and free. But do *not* use SketchUp. See if that has the same problem? This in case weird model geometry might also play a role?
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I wanted to remove a hair while it was printing, and I just sort of forgot that it could suddenly move...
PVA support and printing threads
in Improve your 3D prints
Posted
Well, of course there may exist better settings; it's just that I don't know them. And I don't have an UM3 with supports anyway, only single nozzle UM2s.
Small threads will always be difficult due to the layer lines which distort the shape and cause sort of "derailing". I also found it almost impossible to machine threads in PLA (I tried M3, M4, M5), due to the low melting temp. Even when taking very much time (+10 min) to slowly cut the thread manually, it still melted, and it was not strong enough to fix the screw later on. I think most people will try to avoid threads, and use other methods. That is the background idea for heating and making the whole model softer, and then forcing it on the other part and let cool down. This works well for rough shapes like clamps, but I can imagine that it may not be optimal for finely machined parts like photo equipment. I guess it will require trial and error. If you would find a good solution, please let us know.
By the way, any models in PLA will become soft and distort anyway, if you leave them in your car in the sun, even on a mild spring or autumn day.
The first image below shows the clamp which had to fit over a big glue clamp, so I heated it and forced it over it. The thin colored plates are supports to get it printed on my single-nozzle UM2. It are separate plates for easier removal.
If you don't mind a bit of uglyness, you could also use external screws to hold parts together, as shown in the other models below. These are clamps for laboratory equipment. It takes less time to design and print them, than to search and buy.