Originally Posted by Knife Liddle
The way it`s done Steve is to add a third bearing at the spot where the motor would normally mount in the fan. Then the long shaft extends thru the front bearing. It works great and there are no vibration or safety issues.
Just because "thats the way it is done" does not make it good engineering practice.
While we are discussing engineering--you don't have nearly thick enough iron behind the magnets--you can get away with less iron when you have high pole counts and small gaps between the poles but when the pole count goes down the steel needs to get thicker to close the magnetic path. I am guessing that your outer ring will have a lot of flux leakage. I would guess that you need at least double the steel and maybe more. Yes it will run---but you are not making the best use of the magnet strength.