That sir is why it is a mystery to engineers.
I have no rational answer and that is why it's a mystery to me.
The only plausible solution would be to manufacture a precision traveling armature capable of holding and securing the cutting tool with high precision relative to the the existing tunnel.
A "tunneling machine".
Edited 2 time(s). Last edit at 13-Feb-16 20:15 by Jon Ellison.