[sdiy] making traces curve in eagle

[Julian]

Im using Eagels auto route function, and trying to get it to make smooth curves and not angular changes in direction - the reason 
being is that my cnc machine will glide arround smooth curves, but has to decellerate for hard angles.

Ive been messing about with the costing, and have set evreything to zero, except for vias (i want it to keep on one side) but thats 
not working, so its evidently not in that section.

Any pointers?

Thank you,
Julian