OpenSCAD model to generate adapters between any 2 standard computer fan sizes.
All dimensions in mm.
fan_A_size
fan_B_size
Any standard fan size from 20 to 250.
Or may also use any arbitrary size if you supply *_screw_size and *_bolt_pattern, and possibly adjust cowling_thickness.
This is the outside dimension of the entire fan frame body.
The rest of these settings have reasonable defaults or automatic values, and these are manual overrides to customize the adapter more.
angle
Make an angled adapter with a bent tube between the two flanges. Requires BOSL2.
0-360 The two flanges will be angled this many degrees.
fan_A_bolt_pattern
fan_B_bolt_pattern
Override the bolt pattern spacing.
auto or -1 Automatically determined from the fan size.
fan_A_screw_size
fan_B_screw_size
Fastener size, ex: 4 for M4 screws, not the exact hole diameter. The actual hole diameter will be smaller or exact or larger, depending on *_mount_hole_type .
auto or -1 Automatically determined from the fan size.
none or 0 Do not make any screw holes.
fan_A_mount_hole_type
fan_B_mount_hole_type
How to interpret *_screw_size to get the actual hole diameter to drill.
thread or 1 Holes will be smaller than *_screw_size so that the screw cuts threads into the material, and screw head pockets are disabled (just the narrow hole is drilled all the way through the part).
exact or 2 Holes will be exactly *_screw_size. Not usually what you want. This is a way to manually override and specify an arbitrary size hole exactly.
through or 3 Holes will be larger than *_screw_size so that the screw passes through the hole.
fan_A_screw_pocket_diameter
fan_B_screw_pocket_diameter
Diameter of the pocket around the screw hole for the screw head. Ignored if *_mount_hole_type=thread .
auto or -1 2 x *_mount_hole_size
none or 0 Disable screw head pockets.
fan_A_flange_thickness
fan_B_flange_thickness
Thickness of material under screw head. Only affects holes that have a screw head pocket.
default or -2 or auto or -1 Use default_flange_thickness
default_flange_thickness
Thickness of both flanges.
auto or -1 Use minimum_screw_flange_thickness
0 No extra flage thickness on the faces. This is the smallest possible adapter (while still maintaining a 45 degree transition funnel), but does not leave a lot of material around the screw holes. Possibly more useful with no screw holes and use glue instead.
1 to 4 depending on fan sizes are reasonable values if you don't need the slimmest possible adapter. This provides more material around the screw holes and makes the part stronger.
Default is only 2 because by default the flanges are not flat and have extra material besides this, but for example if you set tunnel_length=0 you probably should increase this to 3 or 4.
minimum_screw_flange_thickness
If any screw head pockets will be formed, this sets the thickness of material under the screw heads.
If *_flange_thickness is greater, the screw heads will have *_flange_thickness material under them.
If *_flange_thickness is less, the screw heads will have minimum_screw_flange_thickness material under them.
tunnel_length
Transition/tunnel length. The distance between the two flanges, not including the flanges.
auto or -1 Automatic length to create a 45 degree transition funnel for straight adapter.
For straight adapter: This may either lengthen greater than auto, or shorten down to 0.
For angled adapter: The disatance is the arc length through the center of the bent tube, and "auto" will be whatever results from arc radius = large fan radius at the given angle, or the straight adapter default tunnel length, whichever is greater. The given distance will only be used if it's larger than whatever "auto" works out to.
xoffset
yoffset
Move one flange off-center.
Eample: xoffset=abs(fan_A_size-fan_B_size)/2 makes both flanges flush on one side.
fbp()
Table of all recognized fan sizes and their assosciated bolt patterns.
Both the internal cone/funnel shape and the external pyramid shape are 45 degrees, and so generally do not require any supports for straight adapters.
Angled adapter with angle>45 will need supports.
Printing with the large side down works better, both because of the increased bed adhesion area, and because of how the interior circular leaning-in overhang supports itself better similar to how an arch supports itself by resisting compression around the circle, vs an exterior unsupported overhang.
If screw head pockets are enabled, the upside down pockets come out slightly messy but not enough to matter functionally, and not enough to be worth adding supports and messing up the smoothness of the inside funnel.