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Smithy

Printcore AA 0.8 quality issues

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I just bought another print core AA 0.8 to speed up some of my functional prints where it is not so important how smooth the shell quality is. Generally the quality is quite good, with the 0.8 print core and printed with the Cura "Extra Fast" profile 0.3 layer height. But in some parts of the object, there are some strange failures and I have no clue how to fix it or if it is just the result of the fast printing. But if so, why just on some layers and not on every layer on this specific part of the object?

 

Here two pictures, which shows the problematic part and the backside which is fine.

IMG_0340.thumb.jpg.5cdaf82712d9b5df304b20f5e3ed219d.jpg

 

IMG_0341.thumb.jpg.a89e8f2fbc9a098507fdf994be173dca.jpg

 

Maybe something with in infill? That due the infill the outer shell looks in some layers not correct? I would understand that due the print speed and so on, the quality could be not so good on "problematic" parts (rounding, etc.) but I don't understand why just on a few layers and not for the whole height.

 

And whatever reason it is, any chance to fix?

 

Thanks!

Christian

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In the lower photo - those randomish layer lines are most likely caused by a dirty Z screw.  Get a box of qtips and some wd-40 or oil and clean out the threads - it's a triple helix so make sure you get all 3 threads (or is it quad?).

 

The upper photo - that's strange looking.  It could be partially caused by loose belts but loose belts are incredibly rare on UM2 and UM3 and S5.  Pluck all 4 belts - both sides - while the print head is in a corner and make sure they are all roughly similar (roughly 60 to 200 Hz on a guitar tuner).  No need to use the guitar tuner app - they should just be all similar - possibly one twice as loose.  When belts are loose (or friction is very high - also put one drop of oil on each of the 6 rods in the gantry) you get walls sticking out a different distance depending if the head is traveling around the outside clockwise versus counter clockwise and so you get regions where the outer wall moves in or out.

 

More likely it's something in the model or cura.  I'd look at that region carefully in Cura.  There are lots of settings that might create this (and of course the model itself!):

 

optimize wall printing order

outer before inner (turning this on hides infill from showing through but makes overhangs worse)

infill overlap

combing

z seam

outer wall wipe distance

retract at layer change (turn that crap off)

 

 

 

Also you might want to slow all the printing speeds down to 30mm/sec and lower the nozzle temp by 10C just to see what happens.  In general slower and cooler results in better quality.

 

I would concentrate on looking at the part in layer view first and if I couldn't figure it out I would toggle all the above settings and slow it down and change the temp to see if it got better and if so then reverse half the options at a time (binary search).

 

 

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I just realized this is an AA 0.8.  Some of the profile settings are pretty bad in that profile.  You might want to start with the AA 0.4 profile and change the line width to 0.8mm and layer height to 0.3mm.  One in particular is the "retract at layer change".  Make sure that is off - that alone could explain most of what you see here.  I like to do 0.3mm layers and 35 mm/sec with my AA 0.8.  The parts look quite good - the layer lines are not so bad and it prints 4X faster than my 0.4 nozzle prints.

 

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Thank a lot for your help and very informative description of the problem!

 

The UM3 is quite new, 2 weeks old, but I checked the belts, all are in similar condition. I will also check and clean the Z screw, unlikely it is already dirty within this short time, but who knows.

 

How can I use a AA 0.4 profile with the AA 0.8 core? I assume to duplicate the AA 0.4 profile to have a custom one, modify your suggested parameters and then select this with the 0.8 print core, right? Because otherwise, the default profiles are unavailable if 0.8 print core is selected.

 

Beside the small cosmetic issues, printing with AA .08 makes really fun when not too much detail is required in the final object and it is a lot faster than with the AA 0.4.

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I tried now to use a 0.4 profile as base and changed the suggested parameters (line width, layer height) and saved it as custom profile. But when selecting the AA 0.8 print core and my created custom profile, the material is showing an orange background, alerting an issue.

 

Is this normal due the 0.4 profile I used as base for my 0.8 custom profile and can I print anyway or is there another problem I don't see.

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I've never saved a profile (instead I use save project - different process but hopefully doesn't matter). Then later I load the project of a similar part that I'm printing this time.  

 

Well I assume you are trying to save time.  That's really the only reason to use a 0.8.  Here are some starter settings to try:

 

1) Set ALL the line widths (there are maybe 6 of them?) to 0.8mm.

2) Set the wall thickness to an integer multiple of this (e.g. 0.8 or 1.6 or 2.4 or 3.2).  If you chose 0.75 for line_width then of course use .75 or 1.5 or 2.25 or 3mm etc).

3) Set printing speed nice and slow - I like 30mm/sec.  Thick layer heights and line width is how you get speed without losing quality.  Raising the "speed" is not good.  More important than setting it to 30mm/sec is to set ALL of the printing speeds (except initial layer which can be 20mm/sec) to the same value.  

4) Layer height - I've been happy with 0.3mm and haven't tried 0.4mm.  

5) To further save significant time eliminate infill or use variable infill.  There may be a bug with variable infill and 0.8mm.  I got it to work for me but it was a struggle so leave this disabled (equal to 0) initially.

6) To further save time make your wall width thin - I like 2 passes (1.6mm)

7) Make sure it doesn't retract on layer change - that was my biggest annoyance with the AA 0.8 profile that I sometimes start with.

8 ) Turn off accel control and jerk control.  If you don't like the resulting ringing then turn them back on.  I prefer the ringing over the reduced tolerances (for example you get bulging corners with accel control turned on).

 

It's okay to start with the AA 0.8 profile.  I've just had bad luck with it and have had to change so many things that it seems almost better to start with AA 0.4 but I don't think I ever actually started with AA 0.4 myself.

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Many thanks gr5 for your very helpful answer! From print to print and from reading a lot here in the forum, I already learned a lot in the last 3 weeks and from day to day it gets better! Of course also to all other contributors here - this  really a great community!

 

Back to topic:

You are right, I haven't thought about projects instead of profiles, but with a project I think I can also save "Extruder 2 disabled" for example or a specific material or whatever. So I should better prepare some projects and have everything in place with correct settings depending on the need.

 

And yes, I want to have speed and if possible acceptable tolerances. I printed over the weekend some tool holders with the AA 0.8 print core and CPE and it worked, but they have a terrible look and surface quality - but I printed them with the default profile and just turned off the retract on layer change as you have advised. For these tool holders the quality was not important, but I will try your suggested settings now for other things, which should have a better look and feel.

 

I don't expect a superb quality with the AA 0.8, but I think with the correct settings it should be possible to get a good speed/quality balance for some bigger functional parts or whatever.

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You should be able to get pretty good looking parts with 0.8 (2-4X faster than 0.4) as long as you keep the speeds at 30mm/sec.  Top surfaces don't look as good but cylinders and cubes look just as good as with 0.4mm and many other shapes do quite well.

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@gr5 I have one more question: Do you adjust the temperature when printing with 0.8 core? I read in the UM knowledge base, that for example PLA which is printed normally with 210° and 0.4 core, they go up to 240° when using the 0.8 core.

 

Do you also make some adjustments? From 210 to 240 sounds a little much for me at the first moment.

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I agree that sounds like a lot.  I usually print with the same temperature.  If you are printing near the limits of capability you should raise the temp.  On the UM2go I print with the same temp and print about 3X more volume than with the 0.4mm nozzle.

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Damn.  Didn't mean to post the above - meant to start a new paragraph.

 

Anyway on the UM3 I just use the default settings in cura usually for temperature (but turn off that stupid retract on layer change thing that made it's way inexplicably into the AA 0.8 profile).  I change other things - I set all the speeds the same.  I like to print slow (30-35mm/sec) and thick (0.3mm) with line widths at 0.8.  But I haven't had to mess with temperature on the AA 0.8 profile.

 

Also on the UM3 if I use a 3dsolex core I have to lower the temp on the 0.8 nozzle versus an Ultimaker AA 0.8 by 10C or it will string a lot.  the 3dsolex core heats the filament more thoroughly because of the dual passage that the filament travels through in the nozzles.  So you don't need to raise the temp at all with the 3dsolex core.

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So, first test with your recommended settings. (0.3 layer, 35mm/sec for everything, retraction on layer change off, etc) A lot better than with the default profile, but I am not happy with the quality of the walls. But I am not sure why this happens. It looks like the layers are not correct aligned, but not single layers, it looks like that a block auf 20-30 layers are ok, then the next 20-30 layers are not exactly aligned with the previous one on the y axis.

 

Another possibility could be, that the inner parts of the object are causing this effect, but on the other hand, the same object printed with the 0.4 print core and 0.15 layer height, is fine and walls are perfectly aligned. I will try it now again with Wall Line Count of 3 (this print was 2) (Wall Thickness 2.25, because is have 0.75 Line Width). 

 

Or do you think it is due the Line Width 0.75? UM takes such values (7/8) instead of 0.8, so I tool also 0.75 for this print.

 

Here are some pics:

IMG_0344.thumb.jpg.3597de868ebbb268027c16a6e7ed668f.jpgIMG_0345.thumb.jpg.c334ba99dd8baafee2b2875002c245bb.jpgIMG_0346.thumb.jpg.72d83367c4c238972a7bd41b20a78fc4.jpg

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10 hours ago, Smithy said:

Another possibility could be, that the inner parts of the object are causing this effect, but on the other hand, the same object printed with the 0.4 print core and 0.15 layer height, is fine and walls are perfectly aligned.

 

I think, it's more or less a matter of temperature and material characteristics (shrinking). With a bigger nozzle a lot more material is deposited in the same amount of time. That means: the material takes longer to solidify. And the amount of time that is needed for one layer is much longer at layers where the inner fins are present.

In addition: because of the wall thickness there are parts that consists of walls only, and other parts (the fins) which are hollow (or with infill). The extruded path shrinks in a different way and the effect is more visible for thicker lines.

Does this make sense?

Which material is it? PLA?

I would try first to print cooler, at thinner layer height (0.2) and then slower. You can also try higher values for the "minimal layer time" (this should dynamically adjust the speed then).

The time saving effect will be reduced of course, you'll have to find a compromise (as always...)

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I have tried now a test with same settings as above, but with 3 walls and increased the temperature to 230°. It is much better, the misalignment is still visible, but very rare.

 

Next test is, 2 wall again and 220°, because 230° was a little bit too much.

 

I search the web about this misalignment mainly on the y axis, but found only reasons like belt tension and something like that, so mainly hardware issues. But when I print with 0.4 print core I don't have this issues. Only one thing is untested, I have my 0.4 core in the left position and the 0.8 core in the right position. Maybe I should put 0.8 left and retest it. But in my understanding it is unlikely that the misalignment is dependent of print core position in the head.

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5 minutes ago, tinkergnome said:

Does this make sense?

Which material is it? PLA?

I would try first to print cooler, at thinner layer height (0.2) and then slower. You can also try higher values for the "minimal layer time" (this should dynamically adjust the speed then).

The time saving effect will be reduced of course, you'll have to find a compromise (as always...)

 

Sorry, haven't read your reply before I posted the update. 

Yes this makes sense, could be really the problem. So I will retest it with a single wall count and with lower temp.

 

Yes material is PLA (Ultimaker)

 

Keep you updated, thanks a lot....

Edited by Smithy

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@tinkergnome: You were right, it seems that the layer misalignment comes from the inner parts (infill, no infall just walls, etc.) So maybe this object is a bad example or test object to justify the print settings.

 

I have now printed a calibration cube and a benchy with the 0.8 print core, 35mm/sec speed, 0.3 layer height. The noticeable misalignment of the layers are not there, so one more reason that it was cause by the object before. But I am not sure if I should be happy with the quality or not. I just know my prints with the 0.4 print core and there is normally print with 0.15 layer height and the prints were nearly perfect. I want to achieve some speed improvements for parts that must not be so beautiful and therefore I bought the 0.8 print core. So I am not sure if this output and quality is ok and normal for a 0.8 print core with 0.3 layer height or not and if I have to justify and play a little bit more with the settings. @gr5 wrote, that his 0.8 prints are nearly the same as 0.4 from the walls quality point of view and just the top layer quality is not so nice.  But when I look on my prints, these are far away from my 0.4er print - but maybe this is normal, because I cannot except the same quality with such a "rough" setup.

 

I also attach the 3mf file, with my settings if this helps.

PLA_08_benchy.3mf

 

Here are some examples:

IMG_0347.thumb.jpg.cc5015009391351a2ac2348ae9ada255.jpg

IMG_0348.thumb.jpg.8a6cb17b5102217bd45d3f249cdfe12a.jpg

IMG_0349.thumb.jpg.c885d44b9d0a69f2fac5362c763de935.jpg

IMG_0350.thumb.jpg.67dfc4b303d0903fc9d9e54b3a918d22.jpg

IMG_0351.thumb.jpg.c61eae3f8e1f5257f4eba2b8dc907700.jpg

 

Thanks a lot!

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You have to decide what you care about the most.  Speed?  Beauty?  Accuracy?

 

There are tradeoffs.  You should pick one of the 3 and ignore the other 2 as much as possible.  Which of these 3 things do you want to learn to do first?

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I know and thats hard to decide 🙂 

I want to have speed with acceptable look and feel. I know that if I want to have beauty that I have to print with 0.4 print core and a layer height of 0.15 or lower. Thats also good for accuracy or better for the accuracy I need. You gave me in another post wonderful hints how to improve accuracy and to get rid of bulging corners and it helped a lot. So I am already in a steep learning curve and try to hammer it in my mind, that I cannot have all three of them at once 🙂

 

But what would you say to the objects (cube, benchy) in my previous post, is this ok for the 0.8 print core and with the settings you suggested. My problem is, that it is my first 3D printing experience and I have no feeling what is normal and what not. If the benchy looks normal for this print setup, I am happy with it, but I am not sure.

 

Thanks!

Edited by Smithy

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I have printed now some objects with the same settings as before (the @gr5 recommended) but with 0.2 layer height as @tinkergnome suggested) and the beauty is much better and good for me. Of course it is more time consuming now.

 

I understand (and accept 🙂) that more speed, thicker layer etc. costs beauty and quality, but for example with 0.3 layer height, the quality is not rough over the whole object. The visible layers etc. are not what I dislike on these settings, it is more the sporadic failures that were produced in the middle of a wall or on some other "uncomplicated" parts. 

 

Maybe this is normal with such thick layers, but I haven't found pictures of other prints with a 0.8 core and thicker layers to compare it.

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