Tolerance...as an engineer, I would assume you understand this and the purpose that it serves.BTW the reason the CNC alloy hubs would be quieter is all down to flex and balance. As the OEM plastic hub flexes (even 0.5mm) the prop is then off balance with the motor bell housing, and you will get vibration and other strange noises. I agree, the CNC alloy hubs are way quieter and smoother - and better for reducing visual vibration because flex is minimised and the prop stays in true alignment with the bellhousing.
One thing to point out, I know there are some "cast" alloy hubs floating around on the interwebs. Use only CNC hubs. There are so many issues with rotating cast parts, as well as they can be extremely brittle and have internal flaws during the casting, making them even worse than the DJI OEM hubs...
Plenty...go visit your local hardware store...if you need an r/c related one, visit your local hobby shop, ask them if they have one or what their tech usesAnyone had any luck finding a suitable torque wrench (that doesn't cost $1,000 USD)?
So it seems reasonable to conclude that any failures are likely due to over tightening of the hub?
I'm starting to think the folks that were hoarding screw on props are looking like geniuses.
As you should, you are told by DJI to replace them after 200 flights, its a wear and tear item.I tend to agree with your comments about pilots panicking and over-reacting.
These hubs and springs are very cheap to buy, so if you are worried about them why not just routinely replace them.
At least your DJI warranty will then be protected!