This fan is designed to be installed on ER11 collet. It's inspired by another one here on Thingy, but this one is installed on top of the ER11 so it can stay all the time and it's not falling off. It works very well with ER11 wrench (like on the picture). You just need to press fit it (if it's little tight - head up inner part a bit).
It blows quite strong - no chips stay on the working area (see picture). No problem with 10krpm - I've used PLA.
With my small motor, installing fan ads around 0,2W of drawn power.
More my CNC upgrades: https://www.thingiverse.com/Saur0n/collections/sshop-cnc
Thickness of the walls is 1,2mm - so with 0,3mm nozzle it should be 4 perimeters. With 0,4mm nozzle it's going to be 3 perimeters. In both cases no infill should appear/be needed after slicing.
No support or raft.