This is the process I use to cut the "drive" into the prop driver. Very simple, and works a treat. Using the cross cutter move it about 3 thou into the work. I have divided my chuck into 20 divisions with a simple texta mark. Lining up the mark with anything thin and available I move the chuck to the next division and move the toolpost into and out of the prop driver. Having done that at about 3 thou I then make another cut at 5 thou, and this is the result. you will see there is a prop washer - but I won't be doing a drawing for that - something to be designed and made yourself - or just use a 1/4 - 6mm propriety one.