KISSlicer Overhang-Bug (All Versions + Stable Release)

[Beefi]

It's a Qidi X-Pro printer with a 32-Bit MCU.

Important: A cool parameter of 0.5 m³/s or even 0.001 m³/s doesn't have an effect to the fan and slow-down...every time (the same overhang) the fan will be set to S194...and the slowest slowdown is about 980 mm/min (16 mm/s) = 1.4 m³/s in my case.
The reason why there is no blob with Cool and Perimeter-flow the same, is because the normal fan-change is only at a destring and not in the middle of a perimeter.


I made some tests and screenshots...


Perimeters: 1.8 m³/s
Cool: 1.8 m³/s
There is NO Slow-down and NO M106 during the Perimeter.

SameFlow.PNG (49.08 KiB) Viewed 4991 times

SameFlowCODE.PNG (80.45 KiB) Viewed 4991 times

Here is set the Cool Parameter to the value 1.7 m³/s:
Perimeter: 1.8 m³/s
Cool: 1.7 m³/s

NOTSameFlow_GCode.PNG (80.69 KiB) Viewed 4991 times

[Beefi]

Hi,

I figured out some logic behind the overhang-feature:

The Cool-Flow-Setting has absolutely no effect on the printing speed of overhangs. The Cool-Flow setting has only effect on the fan-speed (M106-Command) at the overhang, and the max fan-speed for the overhang is dependent on the Loops-Fan-Speed setting.
The only setting which unfluences the overhang speed is the "Min Layer [s]" parameter...also it influences the slow-down and speed-up behaviour. Ok, but the min layer time parameter influences the overall speed. So this is no option.

There is another crazy behave...the Cooling-Fan-Speed for the overhangs is always lower than the normal Perimeter-Fan-Speed
So if you set the fan for loops to 60%, the overhang never has a fan of 60%...the fan is 10%, or 30% (dependent on Cool-Flow-Parameter).
...But especially a overhang needs more fan than a normal perimeter.

At the moment I can use this for workaround:
Setting Cool-Flow to a very high value (e.g. 100 m³/s) and set the the Loops-Fan to a good value for overhangs (e.g. 60%). So you have for Loops, Perimeters AND Overhangs the same fan-speed (in this case 60%) but also the same print-speed.
-> The Overhangfeature is quasi deactivated.

It would be nice for updates in future, that the Overhang-Speed is able to goes down to the Min-Flow-Setting. In my view the overhang feature isn't working right.
Whether you set a loop-fan of 5% or a loop-fan of 80%...the overhang will not be printed slower or faster (the Cool mm³/s parameter is not working right).