This follow focus gear (pitch .8) was designed to fit some Mk1 Cooke Panchro lenses in Arri Std mounts).
The part has been sucessfully printed in PLA & ABS
It fits the following:
Mk1 Panchro 35mm (in Arri Std mount)
Mk1 Panchro 50mm (in Arri Std mount)
Kinetal 12.5mm (in Arri Std mount)
It is a less than ideal fit for some of the other versions, like the Mk2 and a poor fit to the 75mm Panchro (the focus ring champhers are at a different angle). It's best to contact me if you are not sure or want a slightly different design.
It is a two part piece (you will need "part A"
http://shpws.me/M6IP ) , and uses 3 off 2.5mm screw/bolt and nuts to clamp it firmly to the focus ring (If you can't source these, I'll send them for the cost of postage). It is prevented from slipping by using the existing "focus ears" screws. It was designed to be used in conjunction with various lens adapters, eg the Arri Std to PL adapters, where the lens is set into the throat of the adapter... hence the gears are set forward of the piece to easily clear the camera. (Suitable 80mm fronts are also avaliable if required for your matte box).
Cons: the piece does partially obscure the distance marks on the lens, this was a comprimise between secure lens attachment and visability of the underlying engravings.