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danilius

Am I doing magic?

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I recently fitted an olsson block to my UM2, printed out this shroud and fitted that, then kept my machine working 24 hours a day, as usual.

After some silly mistake I discovered I was printing an ABS part without the fans on, and amazingly the print came out absolutely fine. So I continued printing without fans. Well, imagine my surprise when one fine day I accidentally did the same thing with PLA, printing a part without the fans on. The print came out just fine. On the next print I turned the fans on out of curiosity and can't really say it made an appreciable difference.

So I have been printing both these materials now without fans and gotten really great results from the last 30-40 prints, although delamination on ABS is still an issue. PLA can take a heck of a beating before it snaps, and it does not really delaminate.

Can anyone explain this phenomenon; extra points if you avoid explanations that mention pixies, little green leprechauns or Hogwarts?

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I say if it works, keep doing it until it stops working. Its all magic to me. Never really thought the fans did much to be honest considering mine sometimes sound like they are dying. and it was all down to ambient temps, but hey I really don't have a clue. Cooling temperature must be relevant to some extent, but where they are most relevant is another matter all together.

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Like Didier says, it's all down to the model you're trying to print. A large(ish) box will print perfectly fine, but try printing something small and pointy and you'll regret not having your fans on.

As for the delamination of the ABS. Have you tried enclosing your printer? That'll help keep the print at a higher temperature until it's done to lessen the impact of the shrinkage of ABS. Might also want to consider raising the temperature if you're not already at 260C.

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@DidierKlein, you are right, the models are largish. Still amazes me though.

@lRobertl, I did try enclosing the printer and printed at 260C, but it did not make a huge difference. PLA can clearly take way more of a beating than ABS. On the other hand, for master models that will be used for casting, I use ABS since the surface finish is way superior for some inexplicable reason.

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I agree with the flat surfaces being better (as in almost perfectly smooth), but seeing as flat surfaces are easy to sand i find them easier to print in PLA, as this has been my problem lately where i had to print loads of thin flat pieces to make molds from, but did not even want to mess about with ABS due to the risk of wasting tons of time on reprints abs paste and enclosure business. I can guarantee them looking ok in PLA everytime, without even replacing the glue on the glass once, having printed over 50 objects in a row, each with a densly packed amount of objects so it a no brainer for me. I just print, then take them off and print again and again again, and don't even worry about the glue on the bed as the glue im using seems to last forever. It slowly wears off over time but has enough sublte texture to stick even the tiniest objects to it.

ABS is dead to me. A total waste of time in my experience. But i'm only using my printer for art so the thermal properties mean nothing to me as i can always make a mold and cast it in a harder substance if i need it to be more temperature resistant and that way its harder too.

I just couldn't imagine doing this with abs.... I'd worry about the warping way too much.

20150930_162603.thumb.jpg.4fa457350096efdaf96c7a3fb43b890d.jpg

20150930_162603.thumb.jpg.4fa457350096efdaf96c7a3fb43b890d.jpg

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Well I haven't read all the replies to this post but In my personal experience it depends on the part.

For example if I was to print a 1mm cube there would not be enough time for the previous layer to cool before the next layer goes on which can casuse warping or deformation, and the inverse for larger prints so the idea behind the fan is to get to the previous layer cool enough to retain shape before the next layer goes on, as for why you didn't have troubles I would assume that you had a large part or rather multiple parts. Which would increase the TTN as I like to call it or (Time Till Next) Layer that is.

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Fair enough, but these printers take long enough without me extending the time just to let a layer cool a bit, and still there is no guarantee that the corners will not warp upwards over time. Its just to risky, and with real long prints you just don't know until a while in to the print and if you are printing many things as i currently am, all which need perfectly flat bottoms to connect to stuff then I just don't see it possible with ABS. I got quite good with it, but not good enough to guarantee a print, so i just abandoned it as an option. Ive tried all the fan settings, leaving it on/off, putting an enclosure over the printer, heating the bed hotter and a good amount of paste. Sometimes when I thought it would be perfect i came back a few hours later and a corner had very slightly lifted or something else that essentially ruined the print enough for me to get annoyed.

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Trust me I am not advocating for abs in the slightest. I am just trying to explain the purpose and proper uses of the fan/buildplate heater(Environmental Thermal Management)

I forgot to include by the way that if you use too much fan and the print is huge you get the same problem in reverse where the previous layer cools TOO MUCH and that causes bad layer adhesion and can cause warping. Not convinced? take a piece of filament and heat it with a heat gun or lighter on one side which way does it warp...towards the heat...(depending on the material)...the same thing is happening when you let the layer cool the hotend is coming back around to that position and it is reheating that filament (only on one side) and warping it. (thus the purpose of heated build plates) The same general Idea explains heat shrink tubing, and why power lines sag in the summer. I use Simpliy3D to manage the temperature of litterally everything by individual layer. sometimes that takes hundreds of control points and rules but it is easily done if you can make a graph on the temperature you need for layers 1 25 50 and 100 then you can do some excel magic to output the numbers at every 10, 5, or even 1 layer intervals. The good news most of the values are common sense. (if layer 500 needs a 10 second wait time between layers and layer 2 is building just fine than find a happy medium then adjust the line to adjust for layers that take longer or shorter which is also easy to do if you use simplify3d (jeez I should be their wife for how much I'm tooting their horn)

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i have not used simplify 3d so i cant comment, very interesting to know you can manage individual layers so precisely but i feel your layer by layer controls may be slight overkill, but then again you must have your reasons for doing things that way. I find if my first layers are good, the rest are going to be fine. Unless you are printing one single object then large stuff in pla or many small things like in my pic above you dont really need layer management regarding temperature. The most important thing is to test what your filament reacts to best then stick with that.

And with my current pfte issues after replacing the first one, i have many issues, so if i waited for a layer to cool i would get a jam. And that. Would be that. Game over. but in this game every printer has its own personality so you need to know you printer to get good results.

For tiny stuff you need the fans, but to be honest the default settings work just fine for me. I just adjust speed wall thickness and and nozzle temps. And print as cool as i can get away with. the rest i leave alone.

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