This is an axle mount for the turboprops I've been making. It takes 2 bearings that are 1/4in. i.d. and 1/2in. o.d. with the FLANGE that can be gotten on Amazon for 12$ for a pack of 10. It is important that you use the ones with the flange to work properly. I've printed it and the bearings fit just right. I've included the commutator/B.B. bearing parts for the whole thing to rotate on. The copper washers pictured are 7/16 copper washers that you can solder wires to after feeding them down the slots in the commutator post. This will allow for wiring of the generator/motor, that will be mounted to the unused holes in the turbine mount, allowing electrical connection to a rotating commutator. The electrical connecting parts have not yet been designed. When it's done I plan to make an adapter to mount it on a PVC pipe. The bearings are .177cal. (4.5mm) B.B.s. I used Daisy brand match grade shot, as they are precision ground. You will also need a long 1/4 20 bolt to go through the bearing post.