Joakim just released this video showing some of the power of the drive surface machining:
https://www.youtube.com/watch?v=3wVk...b14ju3_E-hKsXA
There is also this older one on the same theme:
https://www.youtube.com/watch?v=qWZd...-hKsXA&index=4
I found both of these to be very educational.
Dan