Hi super_hiker
Like I said before the problem I encountered was on my filament profile. The cooling fan value changed during Bambu Studio update.
Here are the modified value in my case :
There is a nice long thread on the best settings to print with PETG here : [SOLVED] Bad quality when printing PETG - #243 by djeZo888
The current title of the thread doesn’t match the solution provided. Can it be changed?
There have been several suggestions for cleaning the bed.
Considering your proposals for IPA and soap, wouldn’t it be simpler to use a glass cleaner that degreases and leaves no residue? It is super cheap and easy to find.
Oh, I think I have another troubles, because my settings are 100%, 100%, 90%
I have changed the toolhead, cleaned the extruder, run (and failed) 3 calibration tests.
Before, I have printed several models successfully. Now - crashed 4 times.
Bed clean with soap everytime.
I saw how did it happen - the toolhead just crashed the column and totally destroyed it.
Any ideas how can this be fixed? Model file is the same (didn’t change it).
Filament is the same - SunLu Marble.
Tried to print with 50% speed - nothing
Again super_hiker : [SOLVED] Bad quality when printing PETG - #243 by djeZo888
Fan speed, overhang fan speed and printing speed.
According to an online article on Pitambari powder on a foodie website the name is a conbination of “pit” meaning brass and “tamb” meaning copper in Marathi and the founder says “It’s primarily a combination of dolomite powder, tamarind essence, and champaca flower extracts, but it also includes a few other secret ingredients that will… remain a secret.” Another source mentions sandalwood essence for a pleasant fragrance and “Its diamond edge cutting property gives fast cleaning effect.”
Thanks for mentioning it, I’ll probably add some to our household cleaning supplies.
Here is the video when toolhead try to crash the part of the model.
A few moments later:
I tried 5 times with different settings. Every time toolhead broke the same 1-2 columns (marked on the screenshot below)
A few weeks ago, I didn’t have any problems with this model.
I have run out of imagination as to what could be the reason. A bit hard to test this model, it’s 9 hrs of print every time.
You can drop the model into the bed and only print the part from the red line and up.
My guess is that there is a warmer ambient room temperatures (summer time) and the overhangs are starting to curl up. The nozzle knocks them over.
Thanks! I will try to print olny that part.
Not sure about the room temperatures. I have the same cold weather here
Typically, curling is a result of material shrinkage during cool down from the Nozzle temp to the chamber temp. The larger the difference, the larger the shrinkage so warmer chamber temps should actually help (a little).
However, if the fan settings changed since your succesfull prints, that would be a reasonable explanation. Similarly, higher ambient temps previously may help explain why things worked in the past on this sensitive structure.
Other items to tweak for this problem are similar to PETG printing tips:
And of course as Jon mentioned, you only need to print the troublesome areas. The effective lever arm to the bed is shorter, but the break occured well above the line indicated by Jon. So it should work well for a test. Just keep a few centimeters of the base to reduce the heat bed procimity effect.
Thank you very much, EnoTheThracian and JonRaymond.
I’m playing with the adaptive layers in that problematic area.
Not sure how can I change the filling of the thin part in the structure. Starting test_1 with Gyroid
You can add modifiers to a part by right clicking, adding the modifier, moving and sizing it fit the volume you want to change and the changing quite few (but not all) print parameters by selecting the modifier in the objects. I think you’ll likely be fine with global infill changes here though.
Ah…nothing…the same problem, it’s crashed again.
Printed smaller version. When I heard the first thump I turned ‘cham’ fan to 100%. Before that 2 fans were 100%, cham was 80%. In this case smaller version was printed fine.
After that have changed Variable layers in the problematic zone, made the model with the same quolity and speed.
The “Aux” fan is what you want to change for additional cooling. It blows directly at the layer being printed. The “Cham” fan just exhausts the chamber air through the carbon filter and out of the printer.
You might try adding a modifier to the post so they print with more wall layers to make them a little stronger.
In this case I will see more interesting boxing match with stronger rivals 
What infill are you using?
