Cura 5.5 turns off fan for top layers

[rimbo 0]

I've seen it already but it was pretty clear while printing the 20 mm XYZ calibration cube. Cura shut down the fan completely for some 10% of the top layers. I could clearly see the entirety of the infill rising up.

 

In other models, especially for dome-like shapes the tops may turn out as outright gaping holes.

 

Printer

https://lumeplus.wixsite.com/lume

 

temps: bed/nozzle 60/200

Generic PLA

xyz20Calibration_cube1278865 N04r02.3mf

G-CODE xyz20Calibration_cube1278865 N04r02 t200b30-60 fan0-100od2war wLc2 t14m 3g.zip

Edited December 7, 2023 by rimbo

[GregValiant 1,351]

The fan speeds in those gcodes are bouncing all over as the print approaches the top.  I've never seen that before. Cura has added an M107 line at layer 94 so yes, the fan is being shut off before the top.

 

With the model loaded and Cura set up to slice, use the "File | Save Project" command and post the 3mf file here.  This might be a setting issue.  Your "Regular fan speed" is set to zero.

 

Edited December 7, 2023 by GregValiant

[rimbo 0]

Resliced without changing the previous settings. New 3mf and g-code attached. Do you have some g-code analyzer better that allows you to make a quick "at a glance" scan on a G-Code. I think Prusa has a g-code line preview while viewing G-code in UI. I haven't seen anything like it in Cura.

 

SCP_xyz20Calibration_cube1278865 N04r02 FORUM comment-328234.zip

[GregValiant 1,351]

I use Notepad++.  You can open them in regular Windows Notepad as well.

 

You have the "Regular Fan Speed" at 0.  Cura is adjusting the fan speed per the setting "Regular/Maximum fan speed threshold" which you have at 10 seconds.  When the layer time falls below 10 seconds the fan speed approaches 100%.  When the layer time climbs above 10 seconds the fan speed goes to "Regular" which is zero.  So what you are getting is expected behavior given your settings.

Set that regular speed to what you want it to run at and the fan will stay on regardless of the layer time.  You could also set the threshold to 0 in which case the fan will run at that regular speed starting at layer 36 and continuing to the end.

[rimbo 0]

48 minutes ago, GregValiant said:

I use Notepad++.  You can open them in regular Windows Notepad as well.

 

You have the "Regular Fan Speed" at 0.  Cura is adjusting the fan speed per the setting "Regular/Maximum fan speed threshold" which you have at 10 seconds.  When the layer time falls below 10 seconds the fan speed approaches 100%.  When the layer time climbs above 10 seconds the fan speed goes to "Regular" which is zero.  So what you are getting is expected behavior given your settings.

Set that regular speed to what you want it to run at and the fan will stay on regardless of the layer time.  You could also set the threshold to 0 in which case the fan will run at that regular speed starting at layer 36 and continuing to the end.

I'm not a developer but to me it's hardly "intended". The "Regular/Maximum fan speed threshold" should only affect the transition time between the speeds. In my mind my setup should be interpreted to "Up to and including layer 2 inhibit the fan to 0 RPM, then  run at full RPM". The threshold should apply only around layers 2-4 or something like that.

In the current implementation however, how do I alter the setup to achieve my intended behavior?

"Up to and including layer 2 inhibit the fan to 0 RPM, then  run at full RPM"

 

While we're at it, it is worth noting that the fan speed settings are reversed!

If I put

Fan speed 0

Regular fan speed 100

at layer 2

 

the result will be:

layers 1-2 fan speed 100

layers 3-... fan speed 0

 

At least from my experience.

I might refrain from using those settings altogether to see whether Cura applies some automatic sensibility now 🙂

 

 

Edited December 7, 2023 by rimbo

[GregValiant 1,351]

I never liked it much either.  That's why I've written the post processor that nobody else would.

 

Use Cura's "Help | Show Configuration Folder" command and locate the "scripts" sub-folder.

Unzip the attached file and copy "AddCoolingProfile.py" to that "scripts" folder.  The post processor "Advanced Cooling Fan Control" fill be available under "Extensions/PostProcessing/Modify Gcode" and then "Add a script".

"By Layer" allows you to determine the fan speeds at any point in the file, or to turn it off.  By Layer works well with smaller models.  You can change speeds 8 times and if you need more than that you can add another instance of the post (but without "Remove existing M106 lines" checked).

"By Feature" allows you to configure the fan to run at different speeds for walls, skins, whatever.  Because it takes a few seconds for the fan to react to speed changes, By Feature is better suited to large models.

 

AddCoolingProfile.zip

 

[rimbo 0]

Thanks for sharing the postprocessor! A solid piece of work.

 

Carrumba! I've just noticed I've got only the following settings visible

Fan speed

Regular fan speed

Regular fan speed at layer

 

But there's another! It was hidden in my installation, what the hell?!

Initial fan speed

 

Now I can use:

Fan speed 100

Regular fan speed 100

Initial fan speed 0

Regular fan speed at layer 2

 

And this should work. I'm going to print some delicate models soon so it's going to show.