I drill the prop hubs to 1/8" diameter while mounted on a lathe mandrel that has been machined in place to fit the bore of the prop. A center drill is also used to leave a precise taper in the nose cone for the aluminum centering cone on the prop balancer.
I machine the mandrel to be a snug fit inside the prop bore and then hand press the prop on the mandrel to do the drilling.
I realize not everyone has a lathe in their tool arsenal. Just passing along how I do it but, yes, it needs to very precise otherwise the "balanced" prop may be worse that it was before balancing.