[GMorin]

We were able to cut the weight of EACH gear by up to 50% or so.
The gears have very large diameter hubs. I made an arbor with a key slot to hold the gears on a lathe and turned the diameter of the hubs.
On the thicker hub-less gears, trepanning the faces of the gears works well.
In addition to the lathe work, all gears had holes drilled into them. If you have a Bridgeport mill, this job is a lot easier.