A fellow forum member pm me to ask how exactly I'm drilling all these vent holes to the cases ...
Well,I should give a more extended answer ...
Drilling 300+ holes ain't such fun ...
The job is done really much faster if a bench drill press is being used ,of course ..
Then a square /rectangle piece of kinda thick perforated steel sheet is clamped to the surface to be drilled
and used as drill " guide" .An aproppriate drill is chosen to fit exactly to the sheets holes .
I use 5.5 mm drill for making vent holes .
Now ...
It goes a tad more complicated than that ...
1) Usually I use 140 mm fans .
2) Those fans have usually about 129-130 mm rotor diameter .
3) That means that the fan has an rotor area of π *65 mm^2 = ~13273,2 mm^2 minus the area of rotor center /axis cap.
4) In order for the fan to suck air "freely" without pressure drop ,the incoming air vents ,should have equal or larger total
opening .
5) So,each drill hole has a surface of π * 2.75 mm^2=~23,75 mm^2
6 )13273,2 mm^2 / 23,75 mm^2 = 559 holes of 5.5 mm dia. (I haven't subtracted the rotor axis cap ,in this case here.. )
7 ) Minus the rotor cap area (depending on the fan used ) , about 300-350 holes of 5.5 mm dia should be drilled ,so the fan can suck air freely ,without it's speed and/or pressure dropping .
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Cheers.