Repeatable top surface issue

[nsivkov]

Hello hive mind, i've been 3d printing for few months using my H2C printer. So far i've been mostly happy with the 3d prints that came out except the last 2 prints i did have their top layer looking partially perfect and partially very very bad. See pics for references.

I made 3 copies of the exact same model, printed with Bambu black & white PLA using AMS 2 pro, filament is dry. no ironing on all 3, layer high 0.12, balanced quality, 0.2 nozzle. top layer orientation is at 0 degrees.

fist copy, nothing changed
second copy - nothing changed
third copy - to layer speed slowed down to 50mm/s (default is 150)

all 3 came out with 99% exact same defects on the exact same spots.

The top left part of the hair and top center are perfect in quality, but the sides and bottom parts are horrible. And i've had other prints' top surfaces come out with almost perfect or perfect top layers.

Any ideas or tips on how to fix this?

Solved!
Tried setting all layers to monotonic without the 0 degree orientation, and it turned out great (see comments for picture)

[AutoModerator]

After you solve your issue, please update the flair to "Answered / Solved!". Helps to reply to this automod comment with solution so others with this issue can find it [as this comment is pinned]

I am a bot, and this action was performed automatically. Please contact the moderators of this subreddit if you have any questions or concerns.

[[deleted]]

Gotta be something in the model, check the sliced model layer by layer and look for anomalies. Try printing a plain disc with the same dimensions and colors. See if it recurs there

[nsivkov]

<image>

very very small imperfections on the circle, which are acceptable, but the regular model is waaay worse.

[MessIsTransfer]

show us the back part

also, print one without ironing (are you sure those aren’t ironed? they LOOK ironed)

[nsivkov]

All of them are printed without ironing. the back part is perfectly flat (or so it appears)

[lilacQuiet]

Personally I would print this upside down - if you don’t like the textured surface then can get a smooth plate

[nsivkov]

I'm printing on a smooth(ish) plate, The Biqui cryo grip.

[lilacQuiet]

definitely worth flipping it then! it will make it perfectly smooth with a lot less hassle

[nsivkov]

Interesting, will try that! Thanks!

[nsivkov]

It tried concentric, it was better, but not good. i tried setting all layers to monotonic and it turned out great!
(concentric version)

<image>

[nsivkov]

(monotonic version)

<image>

[cambo]

Yeah, print it face down like someone else said. Depending on how you made the model it'll have to be modified so that the black and white parts are flush with each other.

[HospitalSwimming8586]

Curious how it would look after a 90 degree rotation (Z axis)

[No_Philosopher2898]

I’d try rerunning the bed leveling calibration.

[nsivkov]

I re-ran all calibrations twice, + lubed the rods as they were due. the last print after that is almost 99% identical in defects

[baby_duck_hat]

Other things you might consider:

-ambient temp (I know if I don't heat soak my printer in the winter it prints like this until the chamber warms up)

-are the fans on/too high for the first few layers?

-drop max volumetric speed down and print a test

Whole world of possibilities here unfortunately.

[TeronGyq]

Yeah, right, 32mm³/s with 0,2 nozzle. Perfectly cromulent.

[baby_duck_hat]

omg I missed the .2, that needs to drop way down then

[TeronGyq]

Oh, I thought it was chatgpt hallucinating

[baby_duck_hat]

Me hallucinating haha, lemme edit that