@sv06 @ImTheLiquor
I think I found what causes the bad part cooling.
1. First of all, part cooling fan facing down is a terrible design decision. It sucks hot air from the heated bed, resulting in less efficient part cooling.
2. 4010 fan isn’t powerful enough.
3. Inefficient part cooling shroud which blows from the front and a bit from the left, providing less cooling to the back and to the right side of the print. Some other printers have more advanced shrouds which blow from the opposite sides (left/right).
But these reasons don’t explain why some users like @AdamByram get perfect benchy from SD card (185C/60C/100 fan) while other users like me suffer from undercooling even with 100% part cooling fan.
Here comes reason #4 - assembly issues.
Please take a look at the photo of a part cooling fan base plate:
These hex screws allow some forward/back adjustment of the base plate. Looks like during extruder assembly it can be adjusted all the way forward, all the way back or somewhere in between.
I think this is the main reason of inconsistent cooling on different machines.
Users who suffer from undercooling with 100% part cooling fan should try to adjust the part cooling fan baseplate and see if it helps.
Currently I’m doing some tests and I will share my results later today.