Wind vane (on M8 threaded rod)

This is my creation of a wind vane. I designed it, to use it on miiiike's Vertical Windmill Mk2, but it can be used as a stand-alone.

Allthough the Vertical Windmill Mk2 used carbon fibre rods, I used steel 4mm rods. In the tip of the vane, I use a 8mm rod.

For the bearings, I used 8x16x5(688ZZ) bearings from Banggood:
http://www.banggood.com/Wholesale-10Pcs-16mmx8mmx5mm-Steel-Shielded-Deep-Groove-Ball-Bearing-688ZZ-p-49911.html

I got the rods from my local construction market.
Asse