The very best way to mount an exhaust fan, bar none

Felger Carbon · Post by **Felger Carbon** » Wed Nov 29, 2006 5:05 pm

An HDD is a piece of rotating machinery that likes to make noise. Hard-mounting it is a no-no. Grommets are better. Elastic suspension is best.

An exhaust fan is a piece of rotating machinery that likes to make noise. Hard-mounting it is a no-no. Rubber "screws" are better. Can anybody tell me what is best? Hello? Is anybody paying attention?

I first took my Thermaltake Silent Wheel whose sides I had previously shaved 0.15" on opposing sides, so it would fit in the exhaust fan space in an Athena A301 (or TJ08) case. And I applied very pliant foam to the rear:

Then I used 1mm Stretch Magic and a #22-18 uninsulated terminal, and threaded the SM thru the top two fan mounting holes, and passed both ends thru a single #22-18 terminal (stretch the first one to make room for the second). Then I crimped the terminal "half tight" so the SM could still be pulled both ways thru the terminal, but just barely. I drilled a single 1/8" hole at about the right place on the chassis (location not particularly critical) and used #4 hardware to bolt the terminal to the chassis. That suspended the fan, and I pulled on the SM until the fan was hanging at the right height for the exhaust vent:

This is perfectly usable as it is. I plan to apply two more SM loops to loosely hold the fan to the chassis, so the fan doesn't flop around when moving the case. After I Dremel the exhaust vent, that is.

The fan/foam is not clamped to the chassis, just resting there. And it rests flush because the suspension is connected flush to the case but comes out a ways to hold the fan - and with trigonometry you can figure out the small gravity force holding the fan/foam against the vent. Hint: it's a lot less than an ounce.

The very soft foam strip, with self-adhesive backing, is used to insulate doors etc against air leakage in winter. McMaster 93655K31, page 3352, 1/4" thick by 3/8" wide by 17 feet long. Or buy it at your local home supply house.

You can read more about using SM with a crimped terminal here, along with a couple of sources for the equipment.

Now, go forth and mount your exhaust fans the very best way!

Post by **NeilBlanchard** » Wed Nov 29, 2006 6:21 pm

...are you gonna snip out that nasty lookin' grill? That'll make it a lot quieter, and cooler...

Felger Carbon · Post by **Felger Carbon** » Wed Nov 29, 2006 6:47 pm

NeilBlanchard wrote:...are you gonna snip out that nasty lookin' grill? That'll make it a lot quieter, and cooler...

You missed the part where I wrote "After I Dremel the exhaust vent, that is."

So, no, I'm not gonna snip it out, I'm gonna use cutting disks to Dremel it out.

Xoxide and eWiz have the Silent Wheel at $5 and $6. I'm gonna have to buy a few more...

Post by **NeilBlanchard** » Wed Nov 29, 2006 6:53 pm

Hi Felger,

Sorry, I did miss that bit...

I just replaced my Dremel (that has broken) with a Black & Decker. I like it a lot so far -- and it was almost half the cost of the least expensive Dremel. ($35 vs $60) The thing that broke on my Dremel (the 9.6v battery model) was the chuck lock. The B&D has 6 locked positions vs 1 on the Dremel, and it is a cam lever vs a spring-loaded button. It is probably not going to break...

andyb · Post by **andyb** » Thu Nov 30, 2006 2:56 am

Felger that is damned good work, not only have you found a high CFM/Quiet fan, but you have hacked (dremeled) bits off of it to fit, have padded it againsts the case and now are in the process of suspending it flat against the case, and are about to remove the grill.

Congratulations, I hope that this works out for you.

Andy

Felger Carbon · Post by **Felger Carbon** » Thu Nov 30, 2006 3:44 am

NeilBlanchard wrote:I just replaced my Dremel (that has broken) with a Black & Decker.

Gee. For $28, you could have had this and this!

This 4-speed rotary tool is stronger and heavier than the Dremel. I'm not familiar with the B&D.

Post by **NeilBlanchard** » Thu Nov 30, 2006 10:10 am

Hi,

Here's what I did get:
Black & Decker RTX-6 [Edit: Grrrr, their web page sucks! Look under Power Tools/Rotary Tools/Black & Decker...]
It has a pretty decent kit of accessories and clamps, included. As I said above, I really like the chuck lock -- it is hard to see that it could fail like the Dremel, and it is certainly easier to use when tightening and loosening the chuck. And, it is fairly quiet. [Edit: they list it as a three speed (12,000 rpm; 24,000 rpm; 30,000 rpm), but in reality, it is a 5 or 6 speed, since the dial works in between the low medium and high speeds.]

alleycat · Post by **alleycat** » Fri Dec 01, 2006 5:07 am

Gee, someone has bad manners.

Tin snips will do a neater and quicker job than a Dremel.

jhhoffma · Post by **jhhoffma** » Fri Dec 01, 2006 7:22 am

NeilBlanchard wrote:Hi,

Here's what I did get:
Black & Decker RTX-6 [Edit: Grrrr, their web page sucks! Look under Power Tools/Rotary Tools/Black & Decker...]
It has a pretty decent kit of accessories and clamps, included. As I said above, I really like the chuck lock -- it is hard to see that it could fail like the Dremel, and it is certainly easier to use when tightening and loosening the chuck. And, it is fairly quiet. [Edit: they list it as a three speed (12,000 rpm; 24,000 rpm; 30,000 rpm), but in reality, it is a 5 or 6 speed, since the dial works in between the low medium and high speeds.]

Hey Neil,

I think you'll really like that unit. I got one for Xmas a couple years back and couldn't be happier. I was disappointed at first because it wasn't a "Dremel" (I've gone through more than a couple cheapies), but my bro insisted that it was a good unit. And easier to use and it was compatible with all the dremel accessories.

The fiberglass reinforced disks work the best on EVERYTHING but they are so expensive!

I've thought of doing something similar with the fans in my 3000B, but it will have to wait until after christmas, so I can have some time off work. I got some free samples of Sorbothane, so I also have to put those in my other HTPC to get rid of the HDD vibes.

Rasterman · Post by **Rasterman** » Fri Dec 01, 2006 7:55 am

I don't know if you will hear the difference, but you can further decrease turbulence by sanding the 4 plastic motor mounts so they have a cross-section teardrop shape. Also get some shrink tubing and put it around the fan wires and behind a motor mount.

Where did you get the Stretch Magic? And is the foam around the fan the same as you used to seal the doors?

Felger Carbon · Post by **Felger Carbon** » Fri Dec 01, 2006 1:00 pm

Rasterman wrote:...you can further decrease turbulence by sanding the 4 plastic motor mounts so they have a cross-section teardrop shape.

Where did you get the Stretch Magic? And is the foam around the fan the same as you used to seal the doors?

In my mounting scheme, the plastic motor mounts do not touch the case, they are not used for support, and they are not in the air stream. Artbeads.com carries SM and has no shipping charge - they stick the stuff in an envelope and mail it 1st class. The foam is primarily used to seal doors, but I haven't used it for that yet.

Rasterman · Post by **Rasterman** » Mon Dec 04, 2006 1:13 pm

By motor mounts I am talking about the 4 plastic 'spokes' that hold the fan housing and motor in the center of the fan. The are in direct line of the airflow in any fan.

crypt0r · Post by **crypt0r** » Thu Dec 21, 2006 9:37 am

Rasterman wrote:I don't know if you will hear the difference, but you can further decrease turbulence by sanding the 4 plastic motor mounts so they have a cross-section teardrop shape. Also get some shrink tubing and put it around the fan wires and behind a motor mount.

Interesting idea...racing bicycles use that "airfoil shape" for their aero tubes.

You wouldn't happen to be a bicyclist, would ya?

SebRad · Post by **SebRad** » Tue Dec 26, 2006 9:33 am

Hi, looks like a very fine way of mounting a fan. Personally I've used very similar door sealing foam strip and using ordinary "super glue" glued one side to the fan and the other to the case. Some what easier/less work, mine have been in place 12 months+ and not fallen off yet. Yes there maybe more possibility of vibration transfer but the foam is pretty soft and my 80mm Panaflos at <1000rpm aren't producing much vibration or noise.
Picture
Regards, Seb
PS if you "decrease turbulence by sanding the 4 plastic motor mounts so they have a cross-section teardrop shape" and can tell the differance then you must have very good hearing or maybe you just need help!

Rasterman · Post by **Rasterman** » Tue Jan 02, 2007 7:53 am

Not an avid cyclist. The idea is from aerodynamics knowledge. The teardrop shape is the most ideal shape for a cross section traveling through air. A tear drop (wing shape) shape has the same wind resistance as a cylinder something like 4-10 times its cross sectional size!

Yes I doubt you would hear a difference, but it might be worth a try.

Another thing I have noticed with all of the current power supplies is they use a net mesh webbing around all of the wire bundles, this is very bad for airflow, yes it keeps the wires together, but a smooth heat shrink tubing would have been a much better choice.