Rich,
Lets talk chains......
In CAD you would define a particular machining step, and can put it on an individual layer/ level ( depends on
what CAD program you are using). I can can't speak for the "100" different CAD programs out there. Now you export the drawing out ( not all CAD programs are created equal nor are their exporting capabilities). Now LC imports the file based on the CAD provided info. LC has some capabilites to fix minor stuff, like a tolerance issue, but i will say that 90% of problems will be on the drawing side! Remember, you will not give me a drawing to look at!
You can't really join chains in LC, but you can move a chain from one spot to another, accurately or roughly, and delete a rapid between them, thus they are now connected ( look at the generated code). in the manual. That's not the way to do it, since it's easier to use CAD to do it. Why do you want to join chains if you thought out the machining process before hand and all is ok before you start?
LC is an importer, not a CAD program ( think i have that in the manual 10 times ), and provides for defining the machining to be applied at the chain or layer level.
Is LC infallable?
No it is not, and neither is any other program out there. DXF issues, read the appendix in LazyTurn if you want to have a better understanding
So you have a number of interfaces, namely: CAD as prepared for a dxf, the DXF creation, the import of the the DXF,
and the interpretation of the information as applied to machining. Along with the above you have some "variables" that can adjust, within some reason, what happens along the way. So no excuses here, but you got to admit it can get complex.
RICH