Please let me clearify the three differnt types of cuts:
1.) Saw cuts are done to rough cut the tube to length.
2.) Tube cuts are miter cuts (straight or angled) done to but two tubes together.
3.) Radius cuts are cuts that are fish mouthed or radiused to fit up against another tube.
All lengths of cuts should be calculated by the length of the material that was cut. Ex. The length of a tube to mate to a flat plate would be the circumference of the tube.