Hmmm.. What to say???

It's sometimes difficult to describe a skill in words. Remember that German in "Those Magnificent Men in their Flying Machines" who was trying to fly a plane by reading the book. It didn't work did it?

Although it can theoretically be described in engineering terms, the real action can't be fully appreciated like that.
Think of it more like dancing than like physics, it's a rhythmic movement process. There's more comes into it than just the process, it's often a matter of just 'how' the head hits the target. Also 'what' the target is plays an important part, not so important with John Henry because his target was always the drill. But if you're working steel then the exact placement of every blow is just as important in determining how much effort is needed.
Each blow is different and you adjust your speed without breaking your rhythm. I know it doesn't sound logical but drop by and I'll show you how.

Bert.