What can I do to at least dampen the vibrations?
Somebody said use some rubber but I don’t know the specifics.
Sorry, I’ve been trying to login at least a couple times a week but haven’t seen any notifications that there were new posts. I tried to watch the video but it says the r/DIY community is private. Just based on your description though I was wondering if maybe you need to balance the fan blade. I’ve had that problem with a few cheap fans and was able to get them to run about 90% more quietly by just eyeballing the blades and bending the one that looked “off” back into place. I think Mattias Wandel has a video somewhere on how to get really scientific about it if you want to get down to zero vibration.