Why do you need to write your own G code?
The next job is to do Caledonian McIntosh bogie stock and these coaches have protruding bolections around the quarterlights. I did a test piece last year machining the bolections using 3D CAM software but this software generated code which was an X or Y raster with variable Z. The problem I have is that the head of the KX1 mill has a tendency to nod when you change direction in the Z direction due to the drive shaft being behind the column, so reproducing small scale detail becomes a bit difficult. I'm caught between a rock and a hard place with the KX1 since if I adjust the head gib to get rid of the play that allows the nodding, moving the head becomes much stiffer and there is then the possibility of losing steps. If I can drive the cutter in waterlines or contours, I can better control the nodding problem in the Z axis. But I haven't managed to source software which will generate waterline toolpaths at a price I can afford.
So I can do it by hand coding, which isn't too much of a problem since all the quarterlights are the same dimensions and I can write a subroutine to do one bolection using relative distancing, then call this routine for every quarterlight with the appropriate X and Y offset. It just means lifting all the X an Y co-ordinates off AutoCAD by hand and writing them into the GCode.
I did consider writing a program to take all the information from a DXF file, but I reckoned that I could hand code a lot quicker than it would take me to learn all the intricacies of AutoCAD's DXF standard.
So if all goes well, I might have a Caledonian 45ft bogie side made, but I am in danger of being too optimistic.
Im just cutting some small bits of S brickwork to bring along
Funnily enough, I won't be needing a lot of brickwork for my layout, but I will need a lot of Glasgow sandstone to build lots of tenement backs.
Jim.
and i have a cunning little trick for tunnel lining 
