This is an openscad file to calculate the length of Pipe, Threaded Rod & Belt needed for various workspace layouts of the project: http://www.thingiverse.com/thing:724999
I based these calculations from the Detailed Assembly Instructions: http://public.vicious1.de/Assembly_Instructions_v0.2.pdf written by Bofferle http://www.vicious1.com/forums/users/bofferle/
, but did change one dimension related to the belt lengths.

I have also written a Visual Basic program to do these simple calculations. I included a couple of screen captures of what the program looks like. It uses .net 3.5 and is located on github:
https://github.com/geodave810/MP_CNC_Calc

This is for the standard US version, but you can easily convert the numbers to metric (multiply numbers by 25.4 to get mm).

I originally wrote the visual basic program & this was an after thought since thingiverse required some source file, thought I would add something useful.

1. Change the variables X_LEN, Y_Len & Z_Ht to match the work area you desire
2. run the program
3. The console window will echo the calculations. You will also see a basic visual representation of what your layout will look like. This part is not for printing of course.

For example, the size I wanted my machine to be was 20x28, so X_Len = 20, Y_Len=28 & Z_Ht = 6.1

You will then see the following output:
ECHO: "Lengths are in Inches"
ECHO: "X Conduit Lengths = ", 31, " x 3 = ", 93
ECHO: "Y Conduit Lengths = ", 39, 39, " x 3 = ", 117
ECHO: "Z Conduit Lengths = ", 14, 14, " x 3 = ", 28
ECHO: "Z Threaded Rod Length = ", 14
ECHO:
ECHO: "X Conduit Lengths = ", 38, " x 3 = ", 76
ECHO: "Y Conduit Lengths = ", 46, " x 3 = ", 92

I also added 4 extra inches to each of my belts in case I decide to make it a little bigger, I will not need to buy more belt.