Hi, I hope this isn't a stupid question - I did a quick search but didn't find anything useful.

Basically I want to CNC mill some hollow machine parts, but I don't know what I'd need to do to get the correct G-code. For example, how would I mill something like a plumbing T-junction? I can see that if I were doing it manually, I would simply rotate the stock to mill the side-t hole perpendicular to the main hole, but how would I go about doing this under CNC?

If I have a 3D-model of the part, do I have to manually create a model of just the holes so that I can pre-mill that into the stock before milling out the 3D external shape?

Also, if I can put up with lower machining accuracy than usual, is it at all possible to mill something that fits on the table, but is larger than the X-axis travel in 2-operations, moving the stock between passes?

Cheers.

Well your axis of rotation in the manual process must be accomplished under CNC control.....so you would need a setup that would allow you to rotate the part.....

Well your axis of rotation in the manual process must be accomplished under CNC control.....so you would need a setup that would allow you to rotate the part.....

OK, supposing I had a rotary 4th axis that would allow me to mill the top,bottom, front and back of a piece with the left/right sides being clamped, how would I go about generating the G-code for each of the machineable faces separately?