I’m trying to put together a silent cooling design on a computer and one thing I need to do is create a custom duct/funnel/shroud for the cooling fan. I’ve created a working mock-up out of cardboard that’s very basic, but I haven’t the slightest how I could create a more permanent, quality design.
Obviously I can’t just forge one from plastic or aluminum so I’m wondering what might be a good method for creating something like this with commonly available materials and without special equipment like CNCs and stuff.
That bevel will be impossible to fabricate. The only way to do that would be to find a material that already has that angle on it, cut it into strips and glue/JB Weld into the square shape, then cut out the overlay piece.
Getting a consistent, flat angle cut out of something without tools. That’s why I said it would be better to find something that already had the angle and use that, otherwise you’re milling/routing which you specified was out of the picture.
ABS plastic is notoriously easy to work with, and plentiful because you can get destroyed cowls from motorcycles for cheap as hell.
Otherwise, I think you’re channeling your creative energy into something kinda useless. Adding that duct doesn’t make for silence, because a fan’s silence is completely dependent on its bearings and RPM.
Best bet might be to try and heat-form something to the existing shape, if that bevel is a negative of the exterior dimension of the fan. You can buy sheets of Kydex for an attempt, hobby stores probably carry it.
Yeah exactly. Plastic cuts easily and forms a shape easily (with heat). Trying to make that bevel out of metal and some simple tools is just asking to slice your fingers open.
The hard edges of the interior surface bezel aren’t a critical (or necessarily desirable, smooth is better); this is just a rough. The important part is just that there is 92mm x 92mm exit created at that position that widens to the 110mm mouth that mounts to the fan.
The purpose of this is threefold:
A) Direct ventilation. The subsequent design will create a channel from the outside of the chassis and concentrate it directly onto the heatsink surface.
B) Positive air pressure. The intake will be filtered and reduce dust intake in the chassis.
C) Use of a 120mm fan instead of a 92mm fan.
A 120mm fan running at 600RPM is going to push more air and be quieter than a 92mm fan running at 900RPM. It will also be much quieter at the full throttle RPM speed than the 92mm fan.
I’ve tested this already with the 92mm fan mounted as is, no modifications, then with a duct to give the 92mm fan direct access to the chassis intake vent, then finally with the 120mm fan blowing out of a 92mm hole onto the heatsink.
Noise and temperature improvements were noted with each modification.
To everyone else who suggested stuff, thanks. I’ll definitely start looking into stuff like the ABS plastic or Kydex. Those both sound promising. Acrylic is too thick for my application, I think, and sounds potentially like something I’d end up slicing open my femoral on.
Ryan, I’m not sure I quite understand the design since I can’t see how it will be mounted to the case. But there are ducts already available for 120 mm fans. Would any of these help?
Yeah, those aren’t going to fit the purpose. It’s got to have a specific size and shape, otherwise it won’t make clearances with other components.
It sounds like ABS plastic might work, since I have a heat gun and it can be cut easily, or EPS/XPS foam, which I can cut with a utility knife or my dremel. I know I can get EPS/XPS at Home Depot, but I’m striking out at finding a local source of ABS sheets. Any suggestions?
Hobby shops and model train shops, anywhere that does R/C should have some stuff. That or you can scavenge your old toys/tools/electronics and probably come away with quite a bit. One word of advice: if you’re drilling into ABS or some other plastic or cutting it with a thin saw, be sure to extract the bit/blade while it’s still in motion. I lost a coping saw blade to ABS when I stopped for a second and it melted itself tight.
