Controllable Pitch Propeller

This is a reverse engineered demo for display at Bay Area Maker Faire. It explains the inner workings of a controllable pitch propeller. Ideally the hub should be transparent but I don't have the equipment. All threads are metric: holes are provided to the right diameter to tap them by hand. Plastic tubing is in English dimensions as that's all that was available locally. The history of the whole project is here: https://www.flickr.com/photos/steamboat_ed/albums/72157643364703844
2021 November 15: I've uploaded Tumble_Block_01. Print two of these, thread them M4 and add M4 x 5mm grub screws. These fasten over the 3/4 in. dia. acrylic tube so that it can be clamped in a vise to mill the slotted cutout. When one side is done simply flip the blocks over and mill an identical slot on the opposite side. Remove the tumble blocks and the acrylic tube is ready to use. 3/4" o.d. acrylic tube is available from Amazon. The piece I used is 19 in. long but anything over 12" should be adequate.