Hello together,
i thought also while for a solution to get rid off the fan vibrations.
I had this also very bad on my align RCE-BL100A. I saw a lot of vibration until a peak till 10 or so in the middle using the spirit diagnostic tab. Not good at all....
Its not only that mostly of the fans vibrate, secondly there wrong mounted to cool in an effective way.
In my opinion the only solution to get completely rid of the problem and as an improvement for air circulation you have to separate the fan from the chassis of the esc. Normally the fan is mounted directly on the aluminium case of the esc. This cant work!
First your vibrations of the mosten used crappy cheap fans (especially with ball bearings, yes they are bad for fans) will be transferred to the esc. And... the airstream cannot flow. It goes directly on the aluminium and blows back to the fan. Thats not a circulation. The webs in the esc are not deep enough to let the airflow go to the sides.
I think that the manufacturs of the esc dont offer a good solution, because of costs.
My solution is seen on the attached photos.Also, if your fan vibrates a lot, its for sure out of balance. These fans are mostly the cheap ones.
If you want to buy a real good fan take a look at my pictures. This fan is absolutely quiet, have vapo bearings and it is balanced. Its good to see, how many bore holes are necessary to get good balance. (I have no connections to this manufactor, its only from my experiences with fans and is an example - Around 10 Euro at ebay)
Take care with the nice looking aluminium fans, mostly offered for rc car motors. They look nice, but i never saw a balanced one and the run often at 28.000 Rpm. (Way to much) And they use around 0,65A at 7,5V. You should use a fan which is declared with 5V and around 0,5W and 10.000 Rpm. (30 x 30 x 10mm) This should have no impact on your bec.
If you have a very bad fan, its possible to balance it, but it takes time. My method is: Separating it from the unit, power it with a separate cell and use soft silikon cables. Take your smartphone and search for an vibration analysis tool app. Im using "SmartTools" on android. Set the vibration tool to its maximum sensivity. Let the fan run and lay it on the surface of the phone. Lay a finger on it, but dont press. You can easy see the vibration. Choose some isolation tape as an example and cut pieces lets say 5x5mm. Put it on one place of the fan (Round zone of the fan to the maximum outside) Take a look on the vibrations. If its worse move your tape in little steps until you find the place where the vibrations are at lowest. Sometimes you have to use more tape pieces over the other ones. Take a drill (Only a holder with drill) and remove very little material on the opposite side of the tape. Remove the tape and test again, until you are satisfied. Be patient, it can take a while
Nothing for people without time and patience....
On one photo to see, this is the original crappy align fan balanded as good as possible for me.
My mounting is handmade of 1mm CFK. It is silver, cause it is foiled. Only for the bling bling ...The rubber anti vibration balls balls are cheap and you can get them on ebay. They have a diameter around 10mm. Airflow is superb. Add on weight is around 5 g.
I dont have a 3D printer, but this would also work i think.
With this configuration i have
absolute no vibrations on the diagnostic tab in the spirit software.
I thinks its not a good idea to fly without fan, especially on hot summer days. That would be to risky for me.
Maybe here in this forum are also people who likes to fumble and have fun with building by yourself.
Greetings from germany
Mario