DIY Hepa (3D printing required) from Big Clive

: Video


Here's the first of the openscad scripts. Openscad is open source 3D design software that is free to download and use. This script creates the fan adaptor for your chosen filter. Measure the hole in the middle and enter it as the variable "filterhole". The other variables can usually be left at their defaults. The script as-is will work with the Silentnight filters sold on eBay in the UK.



Make sure you leave the semicolon ( intact when you enter a new value.





//120mm fan adaptor HEPA filter

$fn=100;

//You can adjust these four variables

//Primarily the filter hole diameter

screwhole=5; //fan screw hole diameter (5)

filterhole=92; //HEPA filter hole diameter

thickness=1.5; //Thickness of plastic layer (1.5)

insert=10; //Length of insert into filter (10)

//Do not adjust anything below here

cone=(120-filterhole)/1.5;

wall=thickness*2;

difference(){

union(){

//flange

translate([0,0,0])

cube([120,120,thickness]);

//taper to filter insert

translate([60,60,0])

cylinder(h=cone,d1=120,d2=filterhole);

//filter insert

translate([60,60,cone])

cylinder(h=insert,d=filterhole);

}

//taper to filter insert

translate([60,60,0])

cylinder(h=cone,d1=116,d2=filterhole-wall);

//filter insert

translate([60,60,cone])

cylinder(h=insert,d=filterhole-wall);

//fan attachment holes

translate([7.5,7.5,-1])

cylinder(h=thickness+2,d=screwhole);

translate([7.5,112.5,-1])

cylinder(h=thickness+2,d=screwhole);

translate([112.5,7.5,-1])

cylinder(h=thickness+2,d=screwhole);

translate([112.5,112.5,-1])

cylinder(h=thickness+2,d=screwhole);

}





This is the second openscad script which will generate a cap for the other end of the filter if needed. It can also make caps for other applications too.





//HEPA filter blanking cap

$fn=100;

//You can adjust these four variables

//Mainly the filter hole diameter

filterhole=92; //diameter of filter hole

rim=10; //size of rim (10)

insert=10; //Length of insert (10)

thickness=1.5; //Thickness of plastic (1.5)

//Do not adjust anything below here

wall=(2*thickness);

cap=thickness+insert;

difference(){

union(){

//seal plate

cylinder(h=thickness,d=filterhole+(2*rim));

//filter insert

cylinder(h=cap,d=filterhole);

}

//filter insert core

translate([0,0,thickness])

cylinder(h=cap+1,d=filterhole-wall);

}