One of the things I remember from being a kid was that having large assemblies rotate was a big pain. Either making a “circle” of weirdly spaced rails for using wheels as bearings, or having a sloppy/ugly/fragile rod connection. So, now that I have a credit card, I made sure to get a bunch of gears, including a large crown gear.
For the turret itself, I was more worried about getting it to look like a turret than making it look exactly like the real one. The angles and sizes are too precise for accurate replication with K’nex, so I am worrying less about the shape than functionality.
I decided that I’d build the mounts and basket at 45° from the hull. This allowed me to use a blue rods on the hull and use yellow rods in a 2-blue-wide hull opening for it to rotate within. On the base of the hull, the turret support ring is a set of 4 gears at 45° to the hull. They are fixed on white axles with opposite rod-clips, and the rotated square is built up with the halfway points of each side green-rod clipped to the hull.
The entire turret and basket are placed on top of a large crown gear, with a blue rod through both axle slots clipped above. This lets the whole thing drop down with a short amount of the center rod interfacing with the bottom of the hull, giving me two planes with support around the axis of rotation. It also gives me the option to put more wires or force-transmitting rods into the turret to allow manipulation from within the hull and have enough room to not chop them up.
