PLA print fails (¿warping problem?)  

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jarosl̷aw.k
(@jaroslaw-k_1552173287)
New Member

Hi, at first I want to excuse you, probably this problem occurred to other people previously but I couldn't find similar issue. And I'm a newbie to 3d printing. Every print so far was made with Prusa Silver filament included with kit.

Background:
I recently got a Prusa i3 mk3 kit from some seller in Poland, I've assembled it (btw, great manual), run calibration and started printing benchy aaand it failed while printing roof and chimney (the print went off the bed and stuck to nozzle). So ok, I've run 1st layer calibration again and lowered nozzle a bit. I've used glue from the stick for the next print, and the tree frog turned nearly perfect (one toe went missing). Later I printed benchy again and it turned great (no issues). I've later printed a whistle and except a few bridging traces from the top of the whistle were loose (from inside, barely noticeable) .

The problem:
So what you do after printing a few pre-prepared models? You fry to print a complicated one by yourself, I've downloaded https://www.thingiverse.com/thing:2255905 and loaded Kerrigan head into Slic3r.
The model:

I've learned that for printing PLA a clean PEI surface is better, so I decided to clean it with isopropanol (I've ordered acetone). So I've left everything on stock and changed profile to 0.1 mm detail, generated G-code and started printing and it came off after printing a few layers. So I've googled it, and decided to add a 10mm brim and it didn't help much. So I've decided to add larger (20 mm) brim and it did hold longer but the same issue occurred . So I decided to raise bed temperature for the first layer to 68*C and raise first layer temp to 215*C and it failed but I've noticed that the print was only loosely connected to the brim. So I've set up first layer temp to 225*C, first bed layer to 80*C (other layers 68*C) and printed again, but I've noticed that when it prints the wings it start hitting the print and this is the reason why this print is coming off. So my newbie conclusion is that maybe the print slightly warps that's why the nozzle starts to hit the print and act as a leverage removing the print from the bed. I tried one more time, I've lowered fan speed by about 10% I've stuck it into my closet (maybe there were some drafts in the room) but it came off at nearly the same time.

I'm really baffled, truth to be told I've bought original i3 mk3 and started print with PLA because I thought that it will be easier. Can you advice me where to look for a problem? I've sorta jumped into conclusions that it may be warping problem but from what I've read before PLA does not warp much, maybe it is a calibration problem? Maybe I should lower cooling fan speed or lower the temperature a bit?

Posted : 28/12/2018 8:35 am
RH_Dreambox
(@rh_dreambox)
Prominent Member

Forget about Isopropanol and forget about Acetone, they are not enough to fix your problems. Acetone is also not so healthy to handle.

You have missed the best advice that has been written here hundreds of times.
Only use detergent and water, wipe with paper, and then leave no fingerprints on the bed. Then you can use Isopropanol between prints.

Bear MK3 with Bondtech extruder...
Posted : 28/12/2018 8:53 am
jarosl̷aw.k
(@jaroslaw-k_1552173287)
New Member

Hmm, maybe. I will try it, but I don't think that it is enough. because at first the print sticks fine to the bed, after the nozzle starts to hit the print (I've seen that the front of the print is lifting) it acts like a leverage lifting it. maybe I should have used a supports?

But I will try washing the bed with detergent.

EDIT: Yep, it seems that washing it with detergent really fixed the problem. It prints more than an hour over my previous longest print (of this model) so yeah, stupid me. I will wait till the end to confirm.

Co probably nozzle hitting print wasn't the cause of the problem but rather a side effect (maybe print was rocking on the bed so there was inconsistencies with the print)

Posted : 28/12/2018 9:09 am
jarosl̷aw.k
(@jaroslaw-k_1552173287)
New Member

Ok I found what the issue was, and maybe someone will have similar issue once.

The problem was wrong first layer calibration. I was afraid to go to low, but after I've watched Josef introduction again i saw it should be safe to go to -1.1mm, I was at -0.830mm and went to around -1.080mm. First layer was no longer stringy but created mostly uniform layer. Printed like a charm later. No problem with bed adhesion even when I went to ABS.

Posted : 31/12/2018 6:45 pm
roy.s14
(@roy-s14)
Active Member

I found exactly the same, I was far to humble in my actions and lowered my first layer more and resolved the issue. A definite solution that should be considered from the onset.

Posted : 03/03/2019 4:16 pm
randolph.l
(@randolph-l)
Honorable Member

Set your live z with this method https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/life-adjust-z-my-way-t2981.html it is far better than the zig zag method in the firmware

Posted : 03/03/2019 8:46 pm
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