I have written a program which fixes any skew or non-squareness of the router by modifying the g-code. This is very useful when milling double sided pcb's.

Another program is included which calculates machining time.

And yet another which removes parallel lines situated closely together. This is handy when milling fine pitch smd pads.

You are free to host the program or provide a link:

program and source

Tjeerd