There is a reason the Bristol Hercules was likened to a Swiss watch running at 3000 rpm. The gear train that drives the 14 sleeves is made up of 28 gears driven from another gear cut into the crankshaft. This image is of the full size engine with the gear case removed.
The first step in making the gears was to prepare all the gear blanks. There are four styles of gear in the train. The gears are 48 diametrical pitch and there are 7 gears of each style required. I planned to make 9 of each just in case. In each set of seven, two of the gears are silver soldered together in a later step. The gears are all made from 1144 stressproof.
It’s a simple turning job to bring the outside diameter to size, drilling and reaming the axis hole and turning a small hub on three of the styles, the blanks are then parted off. The parted face was ground down to dimension on the surface grinder. The blanks are supported on magnetic 123 blocks so the small hub protrudes below.
The blanks are mounted on a gear cutting arbor, two at a time, which in turn is mounted in a 4 jaw chuck on the rotary table. A last word dial indicator running on the gear blanks was use to adjust the 4 jaw so the blanks run true. The gear cutter is positioned exactly on the horizontal center line of the blanks. 
I used the D2nc gear g-code generator, which I added to the program specifically for this build. I created the g-code to cut the gears with 3 passes using the constant volume modified algorithm which is kind to the tooling.
In this image you see the completed gears which go into making up the train, 7 sets of the 4 styles of gear. You can see the marks on some of the gears where I’ve used a stone to remove the burrs around the teeth. As I cut the larger gears in pairs, only one of them needed to be de-burred. I’ve covered the gears in ‘Fluid Film‘ to inhibit rust.
The full size gears have holes drilled in them to form spokes. I guess that was a weight control measure. As this engine will never fly and weight is not an issue, I plan to leave them solid.