Quạt cho đai ốc collet CNC (ER32-UM type nut)

After getting my own CNC machine equipped with the ER20-M collet nut fans and seeing how well they work, I decided to make one for my buddy's CNC machine - he's using ER32-UM nuts and only goes to 18K RPM, however as of the time of writing, it's not yet tested. 

Make sure to print with 4 walls so there is no infill, as that could cause disbalance at higher RPM's. 

These are made for suction, but a simple mirror will turn these into blowers for use in metal processing or without a dust collection mechanism. 

For the ER20-M ones, I tested them extensively and they've been really really good. Anyone testing these out, please let me know - I'm curious how you guys like these. 

PS: the ones on the print plate are 12mm fin lengths, and in my hand is the 20mm fin length.