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esteban-pacheco

Fatal Under extrusion, Top layers looks REAlly BAD,

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Hello Forum ,the quality of my prints is getting worse and i cannot find an answer for it.  the "roof" layers of my prints they look really awful. as an architect i need to deliver sometimes some "previews"of the plans as model, so i got this printer to save time, but,  im getting tired of spending more time in looking whats wrong with the machine than being printing...[media=2688][/media]

this is frustrating because the problems are so random.,, that nobody has an answer,  my machine is  in a good shape,  got a new bowden tube, got a new ptfe coupler, the belts are thigh and all the moving parts are well oiled with sewing machine oil... the Very first layer is always perfect, but then the next ones, you can notice that gradually an under extrusion problem appears (i've printed almost all available tests online  - for example that cylinder with volume marks -  with  to check if theres undersextrusion or not, and all the test prints are perfect.  

so now im very disappointed, and my opinion is that the design of the feeder mechanism hat some weaknesses. im not an mechanic Ingeneer, but for example, inside the mechanism, theres an spring that is doing nothing! no matter in which direction you turn the screw, the person on the filament will not be affected...

i print it PLA from colorfabb, at 210  -  215 celsius degrees. and really slow, 30 to 35 mm/s and NO, im not testing stuff with my printer...

this is so annoying...

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You need more top/bottom layers. Minimum 2. So if you print at 0.1 you need 0.2 top/bottom. For 0.2 use 0.4. For 0.15 use 0.30. With one layer it's almost impossible to get a clean top/bottom

 

I would say you need 5 to 6 top layers if you want really nice quality, so 0.6 when printing 0.1 layers, 0.9 when printing 0.15 layers ....

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Well, im using 5 layers, and infill 20... But the problem appears really early in the prints, as i said, the first layer is perfect, then in the next 4 layers you can see that gradually the quality gets worse, that the layers are not closed, then comes the infill, and the rest is history.

Im really considering getting an sledgehammer and finish this in an epic way... Im spending more time in searching and trying to fix stuff that printing... Thats nit the goal of the whole thing

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new attempt, after doing several times the Atomic method... after levelling the build plate...

using

0.2 layer thickness,

30 mm/2

1.2 top bottom thickness

215 degreees

25 infill

 

don't know what else to say

[media=2696][/media]

everyone has a different theory about whats going on...

Should i change the nozzle?

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What speed are you adjusting? Maybe you ain't on advanced mode. You need to change infill speed to match that speed. Maybe that's the issue.

Also 26 not 25 will make a different pattern in cura. More solid but that's not your issue. It's clearly underextruding. Check that speed.

Edited by Guest

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Neotko: im in advanced mode, so i have:

BASIC:

Quality:

Later height (mm) 0.2

Shell thickness (mm) 1.2

Enable retraction: checked

Fill:

Bottom / top thickness (mm) : 1.2

Fill density (%): 20

Speed and temperature :

Print speed (mm/s): 30

ADVANCED:

Machine:

Nozzle size(mm): 0.4

Speed: (all are set to 0=30mm/s) besides the bottomlayer spped (20 mm/s)

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Whell that looks like understrusion. There are some thinks you can check. The ptfe coupler, the extruder (cleanning the extruder always helps) but for that speed/pla quality/etc. I would bet on the ptfe coupler.

A) extruder tension not enough

B) ptfe coupler burn and making it hard for filament to go.

There's also more posibilities. @gr5 he might point you to a post about this and he it's an expert on um2.

Edited by Guest

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Do you get any 'tocking' sounds from the feed mechanism at the rear? If so, it's possible that the feed isn't working correctly. If the filament unwound OK? Just wondering if you are getting a tangle or the spool is too tightly coiled.

Before trying to change the nozzle I would check to see if the nozzle is clear. I bought some 0.4mm drill bits, heated the nozzle and inserted a bit, blunt end first into the hole and slid it up and down. This cleared out some gunge. You need to hold the drill in some insulating tape otherwise your fingers get burnt. Take care not to break the bit.

The odd thing with you photo is that the infill is not too bad, while the bottom layer is awful.

 

new attempt, after doing several times the Atomic method... after levelling the build plate...

using

0.2 layer thickness,

30 mm/2

1.2 top bottom thickness

215 degreees

25 infill

 

don't know what else to say

[media=2696][/media]

everyone has a different theory about whats going on...

Should i change  the nozzle?

 

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You need to do about 6-8 Atomic pulls in my opinion (or whatever it takes). Then go from there, i had this problem, and it was the fact i was not cleaning the nozzle enough (i mean i wasn't doing it properly). Do it with white until its all white after each pull and you don't see any burn marks or discolouration. Also try printing in 0.1 or less as the more layers it does the cleaner it gets. It looks from your picture that its burning the plastic as it goes over it, which suggests a block to me.

Edited by Guest

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@JohnFox :Thanks JohnFox, ill will try that too!

i made the atomic clean several times, i turned the temperature up to 260 for a few minutes... so i think the nozzle is free, and no, theres no ticking sound coming from the extruder...

what it makes me Angry and i don't know what is causing it... is the fact that the VERY first layer is perfect... really neat and smooth, but after that the next layers get worse and worse (but the shells are quite ok) is just the bottom and top layers that are not closed....

@Neotko: My PTFE coupler is like 5 weeks old... i already changed it...

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When you look down the nozzle can you see through it after an atomic pull? if not then its not clear. And even if it looks clear it doesn't mean that it is, after i figured this out, i have had zero problems, and my PFTE coupler is melted and on its way out, so its not that for sure, i've been printing non stop since November last year.

I wouldn't recommend clearing the head with anything other than atomic pulls as you may damage it and it doesn't mean you will get the bits on the edges just inside the head out as they are also the problem bits and cause slight blockades. You are basically avoiding thorough cleaning if you use a drill bit.

Edited by Guest

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@Cloackfiend: yes i can look trough the nozzle after the atomic pull, i did many many of them... is there other way to clean the nozzle without taking it apart or inserting things on it?

after how many hours do we need to change the nozzle? im considering getting an olson block... im not sure because im the kind of guy that loves to use original parts...

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Can you share the .stl file - i'd love to see if others can get the result you're after.

Did you try the 26% (not 25%) infill as other have mentioned.

I have to admit for me Cura isn't the best slicer for surface quality - as you mentioned it can be hit and miss, but other swear by it so there is a way i'm sure?

And are you sure the filament you're using is okay - have you tested with another make?

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The thinner the layers. the more of them, hence the 45 hours, but in my personal experience with everything stock when i print in .2 i set the temp to 230.

And i understand about time, in your case everything is square so you can get away with more speed in my opinion. i did.

I made some keyrings for work and my settings were: 20 or 30 infill (i think 30?) , speed 50mm/s  

temp 230c layers height 0.2mm and shell 1.2 top and bott. I knocked out quite a few with no issues what so ever.

here are some pics with UM blue and colorfabb red, both done with same settings.

20150614_221452.thumb.jpg.b128e18d005221d30e24e16dd458d044.jpg

my advice to you is to hit the tune button on the front during print and play with the temps, that way you know what works best for your printer and filament! Some people said there was something wrong with my printer if i need to go to 230, but hey thats my printer, and it gives great results, so what do i care what they say. Do what works best for you.

20150614_221452.thumb.jpg.b128e18d005221d30e24e16dd458d044.jpg

Edited by Guest

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@cloackfiend: yes i've reader those posts too saying that if you need to go with play up to 230 is because your printer isn't working properly.... heheh the thing im printing is 20 cms by 12 cms, is a huge piece... i did several atomic pulls until now.. the material is coming our really white, without any contaminants, so lets see what happen overnight...

@Fracfalco:

A) im trying that right now, ill let the printer working over night and see what happens.

b) about the file, how can i share it?

C) you say that cura cannot coupe with surfaces???? so all this issues im having with the bottom top (surfaces) is an software issue?

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If the settings change doesn't help. Try checking the feeder tension (I think it should be able to pull 2 pounds), clean the feeder with a metal brush to remove any prior filaments (less slippery) and check the bowden. Also try to feed the hotend manually from the feeder to fell the bowden tension. It should 'fell' not hard to push. Better to remove any weird possible think before disassembling stuff.

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