RE: Fan speed
@teymen-t
Hello,
Yes you can absolutely do this but you need to dive into gcode a little bit. It's not that hard but you need to edit the gcode file using Notepad or similar text editing software.
Then you need to search for ;AFTER_LAYER_CHANGE in the code. There's going to be one of these lines for every layer. Its a little confusing because the next line is going to be the layer that you are going to be working on, as opposed to the layer just completed. Then insert a line after this for the layer you want to control. You only need to know two commands, using M106 to set the fan speed and M107 to turn the fan off.
M106 S50 will make the fan run at 50 for example. You can find more on this command in the section Prusa specific gcodes, or the Marlin gcode information.
You can edit every layer in the gcode if you are so inclined 🙂
Save the edited file making sure you are saving as a .gcode file not .txt file and you will be good to go.
Part Cooling
The fan control in the slicer is quite silly in my experience, it seems as if its a series of trap doors conspiring to keep the part cooling fan off at all times, and as of this post with 2.4.0 A3 its still the case. I've found the fool-proof way of getting to work and keeping it on is to set the min/max speed at the maximum speed you'd want it to run. Auto cooling is quite lol, keep it checked as well as Keep Fan Always on. Disable Fan for the first (X) layers and full fan at (X) layer does seem to work. The cooling thresholds however seem to not ever be respected.
I think if enough people raise this as an issue it will be fixed, or at least some of the logic worked out.
Imagine
If you a view of fan speed for each later. In sliced view. Then you would be able to sort it out