I dug out my FreeCAD drawings and made images of the drawing. I am adding those images now, and will link the mechanical file. You can open it in FreeCAD, explore the mechanical design of the spindles, find the parts and make your own modifications.
The green PCB holds 8 micro reed switches, surface mount resistors, and a 8 channel digital I2C expander IC. The saft (blue) rotates in a set of two bearings (yellow). A magnet (orange) is held by an acrylic disk (red) which is press fit to the shaft. As the magnet rotates, it pulls the reed switch/s nearest it closed. This wind vane PCB with 8 switches has a resolution of 16 directions, since two adjacent switches may be pulled closed by the magnet.
Both bearings (yellow) are held in place by a two part acrylic disk bearing seat (red). The centering disk is 5mm thick, to match that of the bearing. It's center hole is cut to the outside diameter of the bearing. The base disk is 2mm thick. It's center hole is cut larger than the shaft, but smaller than the outside diameter of the bearing.
Two 5mm "star disks" are press fit to the top of the shaft. It is the 50mm PVC cap that press fits over these the drives the shaft assembly. Between the star disks and the spindle main body is a thrust bearing (silver-orange-silver).
The 50mm 'hood cap' overhangs the 40mm cap
, preventing wind from blowing dust or rain into the space above the top of the spindle body, thus keeping the whole assembly clean and dry. It is to the 50mm cap that arms are attached for wind cups, or a vane and weighted point for a wind vane.
The next file on the way will be the laser cut acrylic files.