1) Install the Flanged Bearings in the two Side Plates. The bearing flange should be on the opposite side of the plate from the counterbores.
2) Install the two Standoffs into one of the Side Plates with two 3/8in long 10-32 button head screws.
3) Insert the through bore shaft into the bearing in the Side Plate with the Standoffs. The end of the shaft with hex should be facing away from the Side Plate.
4) Turn the bottom stack on its side and set it on the Side Plate so that the Middle Plate slots into the notches in the Side Plate. The edges of the Bottom Plate should be flush with the Side Plate.
5) Slide the Bevel Gear onto the through bore shaft.
6) Drop the second Side Plate and bearing onto the end of the through bore shaft.
7) Install four 3/8in long 10-32 button head screws through the Side Plate into the Standoffs and the Bottom Plate. Leave these screws slightly loose.
9) Spin the gearbox a few times and then tighten all screws. Spin the gearbox afterwards to ensure it spins smoothly.